U.S. patent application number 16/212479 was filed with the patent office on 2019-06-06 for printable aluminum alloys with good anodized cosmetic surfaces.
The applicant listed for this patent is Apple Inc.. Invention is credited to Herng-Jeng Jou, Hoishun Li, James A. Wright, James A. Yurko.
Application Number | 20190169717 16/212479 |
Document ID | / |
Family ID | 66658903 |
Filed Date | 2019-06-06 |
United States Patent
Application |
20190169717 |
Kind Code |
A1 |
Li; Hoishun ; et
al. |
June 6, 2019 |
Printable Aluminum Alloys with Good Anodized Cosmetic Surfaces
Abstract
The disclosure provides aluminum alloys with high tensile
strength and appealing cosmetics and improved tensile yield
strength. The aluminum alloys include 0.5 to 3.0 wt % Mg and 0.2 to
3.0 wt % Si. The alloys have a weight ratio of Mg to Si ranging
from 2 to 4.
Inventors: |
Li; Hoishun; (San Jose,
CA) ; Yurko; James A.; (Saratoga, CA) ; Jou;
Herng-Jeng; (San Jose, CA) ; Wright; James A.;
(Los Gatos, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Apple Inc. |
Cupertino |
CA |
US |
|
|
Family ID: |
66658903 |
Appl. No.: |
16/212479 |
Filed: |
December 6, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62595161 |
Dec 6, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22F 1/05 20130101; C22C
21/00 20130101; C22C 1/0416 20130101; C22C 1/026 20130101; C22C
32/0036 20130101; C22C 21/08 20130101; C22F 1/043 20130101; C22C
21/02 20130101; C22C 32/0078 20130101; B22F 3/1055 20130101; C22F
1/04 20130101; C22F 1/047 20130101; B33Y 70/00 20141201 |
International
Class: |
C22C 21/08 20060101
C22C021/08; C22C 1/02 20060101 C22C001/02 |
Claims
1. An aluminum alloy comprising: 0.5 to 3.0 wt % Mg and 0.2 to 3.0
wt % Si, wherein the alloy has a weight ratio of Mg to Si ranging
from 2.0 to 4.0.
2. The alloy of claim 1, wherein the alloy comprises 0.5 to 1.6 wt
% Mg.
3. The alloy of claim 1, wherein the alloy comprises 0.2 to 0.5 wt
% Si.
4. The alloy of claim 1, wherein the alloy comprises at least 0.04
wt % Fe.
5. The alloy of claim 1, wherein the alloy comprises 0.35 wt % Fe
or less.
6. The alloy of claim 1, wherein the alloy comprises less than 0.06
wt % of the one or more elements Cu, Cr, Mn, Zn, and V.
7. The alloy of claim 1, wherein the alloy further comprises up to
0.5 wt % of an additional metal chosen from Zr, Sc, and any
combination thereof.
8. The alloy of claim 1, wherein the alloy has a yield strength of
at least 200 MPa.
9. The alloy of claim 8, wherein a Scheil temperature of the alloy
is higher than a solvus temperature T.sub.solvus for
Mg.sub.2Si.
10. The alloy of claim 1, wherein the alloy has a Scheil
temperature .DELTA.T.sub.80%-99% smaller than 60.degree. C.
11. The alloy of claim 1, wherein the alloy has a solutionizing
temperature window of at least 20.degree. C.
12. The alloy of claim 1, wherein the alloy has a critical cooling
rate less than 80.degree. C./s.
13. The alloy of claim 1, wherein the alloy comprises MgSi.sub.2
particles and excess Mg in the alloy matrix in an amount of up to
about 2 wt % of the alloy.
14. The alloy of claim 13, wherein the alloy has the Mg.sub.2Si
particles of at least 0.15 vol. %.
15. The alloy of claim 1, wherein the alloy comprises 0.8 to 1.2 wt
% Mg.sub.2Si particles and 0.6 to 0.75 wt % Mg within the Al
matrix.
16. The alloy of claim 1, wherein the alloy comprises an eutectic
fraction of at least 5% such that hot tearing from thermal
contraction during solidification is reduced.
17. An aluminum alloy comprising 0.5 to 1.6 wt % Mg, 0.2 to 0.5 wt
% Si, 0.04 to 0.35 wt % Fe, less than 0.06 wt % of the one or more
elements Cu, Cr, Mn, Zn, and V, 0.5 wt % of an additional metal
chosen from Zr, Sc, and any combination thereof, and the remainder
aluminum and incidental impurities; wherein the weight ratio of Mg
to Si ranges from 3.0 to 4.0.
18. The aluminum alloy of claim 17, comprising 0.8 to 1.2 wt %
Mg.sub.2Si particles and 0.6 to 0.75 wt % Mg.
19. The aluminum alloy of claim 18, wherein the Mg.sub.2Si
particles are at least 0.15 vol % of the alloy.
20. A method of making an aluminum alloy comprising: depositing a
powdered aluminum alloy comprising 0.5 to 3.0 wt % Mg and 0.2 to
3.0 wt % Si, wherein the alloy has a weight ratio of Mg to Si
ranging from 2.0 to 4.0 on an aluminum alloy substrate; heating the
powdered aluminum alloy to form a melted alloy on the aluminum
alloy substrate; and cooling the melted alloy on the aluminum alloy
substrate to form the aluminum alloy.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This patent application claims the benefit under 35 U.S.C.
.sctn. 119(e) of U.S. Patent Application Ser. No. 62/595,161,
entitled "Printable Aluminum Alloys with Good Anodized Cosmetic
Surfaces," filed on Dec. 6, 2017, which is incorporated herein by
reference in its entirety.
TECHNICAL FIELD
[0002] The disclosure generally relates to aluminum alloys. More
specifically, the embodiments relate to aluminum alloys with high
tensile strength and cosmetically appealing anodized surfaces that
can be used in additive manufacturing for applications including
use as enclosures for electronic devices.
BACKGROUND
[0003] Commercial aluminum (Al) alloys have been used for making
enclosures for electronic devices, including mobile phones, tablet
computers, notebook computers, instrument windows, appliance
screens, and the like. The enclosures may be machined or additive
manufactured from the aluminum alloys. Generally, additive
manufacturing is a lower cost process than machining processes,
such as computer numerical control (CNC). The commercial aluminum
alloys do not have a neutral color, but rather the anodized surface
is either dark or yellowish.
[0004] Aluminum alloys, such as commercial aluminum alloys, such as
A356 and A383, include high silicon (Si) content, which is
typically greater than 2.0 wt %. For example, the aluminum (Al)
alloy A356 includes 0.3 wt % magnesium (Mg) and 7% wt % (Si), while
Al alloy A383 includes 3.5 wt % copper (Cu), 8.5 wt % Si, and 3 wt
% zinc (Zn). The high Si content in the processed alloys provides
good fluidity for the alloys for additive manufacturing, and also
hot cracking resistance. However, such high silicon contents lead
to formation of silicon particles and other particles such as
AlFeSi- . The silicon particles are non-conductive and are not
anodized, therefore reducing the net amount the entire alloy is
anodized. As a result, the commercial Al alloys, such as A356 and
A383, create dull, grey, unappealing surfaces when anodized.
[0005] In some other cases, low silicon heat treatable aluminum
alloys, such as commercial Al alloy 6063, can form an appealing
anodized surface finish and have a relatively high yield strength
of about 220 MPa. However, commercial Al alloys 6063 have low
fluidity and propensity to crack during solidification and are not
suitable for additive manufacturing.
[0006] Although the Al alloys use high Si or Mn to help
processability, Si or Mn affects the brightness and/or color of the
anodized finish. There still remains a need to develop aluminum
alloys with appealing cosmetics and improved tensile yield
strength.
BRIEF SUMMARY
[0007] Embodiments described herein may provide aluminum alloys
with appealing cosmetics and improved tensile yield strength.
[0008] In one embodiment, an aluminum alloy includes 0.5 to 3.0 wt
% Mg and 0.2 to 3.0 wt % Si, where the alloy has a weight ratio of
Mg to Si ranging from 2 to 4.
[0009] Additional embodiments and features are set forth in part in
the description that follows, and will become apparent to those
skilled in the art upon examination of the specification or may be
learned by the practice of the embodiments discussed herein. A
further understanding of the nature and advantages of certain
embodiments may be realized by reference to the remaining portions
of the specification and the drawings, which form part of this
disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The following figures are provided to disclose non-limiting
aspects of the disclosure.
[0011] FIG. 1 depicts a predicted solidification diagram for
various alloys in accordance with embodiments of the
disclosure.
[0012] FIG. 2A depicts an example Mg--Si composition space with Mg
up to 2 wt % for compositions having various solidification
temperature ranges for Example Alloy 1 containing 0.08 wt % Fe in
accordance with embodiments of the disclosure.
[0013] FIG. 2B depicts an example Mg--Si composition space with Mg
up to 2 wt % for compositions having various solutionizing
temperature ranges for Example Alloy 1 containing 0.08 wt % Fe in
accordance with embodiments of the disclosure.
[0014] FIG. 2C depicts an example Mg--Si composition space with Mg
up to 2 wt % for compositions having various critical cooling rates
for Example Alloy 1 containing 0.08 wt % Fe in accordance with
embodiments of the disclosure.
[0015] FIG. 2D depicts an overlapping composition space of Mg and
Si among Scheil .DELTA.T.sub.80%-99% solutionizing temperature
window and critical cooling rate for Example alloy 1 containing
0.08 wt % Fe in accordance with embodiments of the disclosure.
[0016] FIG. 3A depicts an example Mg--Si composition space with Mg
up to 3 wt % for compositions having various Scheil temperatures
and solvus temperatures in accordance with embodiments of the
disclosure.
[0017] FIG. 3B depicts an example Mg--Si composition space with Mg
up to 3 wt % for compositions having various solidification
temperature ranges in accordance with embodiments of the
disclosure.
[0018] FIG. 3C depicts an example Mg--Si composition space with Mg
up to 8 wt % for compositions having various solidification
temperature ranges in accordance with embodiments of the
disclosure.
[0019] FIG. 4 depicts an example Mg--Si composition space with Mg
up to 2 wt % for compositions having various tensile strengths for
Example Alloy 1 containing 0.08 wt % Fe in accordance with
embodiments of the disclosure.
[0020] FIG. 5 depicts an example Mg--Si composition space with Mg
up to 2 wt % for compositions having various Mg.sub.2Si secondary
phase for Example Alloy 1 containing 0.08 wt % Fe in accordance
with embodiments of the disclosure.
[0021] FIG. 6 depicts an example Fe vs. impurity (including Cu, Mn,
Cr, Zn, and or V) composition space with Fe up to 0.25 wt % and
impurity up to 0.1% for an Example Alloy having various Mg.sub.2Si
secondary phases in accordance with embodiments of the
disclosure.
[0022] FIG. 7A depicts an example of a mold cavity in accordance
with embodiments of the disclosure.
[0023] FIG. 7B depicts an example of a partial mold filling
following FIG. 7A in accordance with embodiments of the
disclosure.
[0024] FIG. 7C depicts an example of a complete mold filling
following FIG. 7B in accordance with embodiments of the
disclosure.
[0025] FIG. 7D depicts an example of partial solidification
following FIG. 7C in accordance with embodiments of the
disclosure.
[0026] FIG. 7E depicts an example of complete solidification
following FIG. 7D in accordance with embodiments of the
disclosure.
[0027] FIG. 7F depicts an example of the alloy in the mold cavity
without any hot tearing following FIG. 7E in accordance with
embodiments of the disclosure.
[0028] FIG. 7G depicts an example of the alloy in the mold cavity
with hot tearing in the middle of the thin portion following FIG.
7E in accordance with embodiments of the disclosure.
[0029] FIGS. 8A-8B depict an example of the middle portion of an
H-shape mold cavity (also referred as a "finger") with varying
thicknesses, FIG. 8A depicts a thinner mold cavity, and FIG. 8B
depicts a thicker mold cavity, in accordance with embodiments of
the disclosure.
DETAILED DESCRIPTION
[0030] The disclosure may be understood by reference to the
following detailed description, taken in conjunction with the
drawings as described herein. It is noted that, for purposes of
illustrative clarity, certain elements in various drawings may not
be drawn to scale, may be represented schematically or
conceptually, or otherwise may not correspond exactly to certain
physical configurations of embodiments.
[0031] The disclosure is directed aluminum alloys that have a
combination of good processability (e.g. for additive manufacturing
and/or non-iron mold casting methods), cosmetically appealing
anodized finish, a yield strength of at least 200 MPa, and/or
corrosion resistance. These alloys combine the good processability
characteristics of commercially processable Al alloys with the
cosmetically appealing smooth anodizable surface finish of
commercial wrought aluminum alloys.
[0032] In some aspects, the aluminum alloys have a weight ratio of
Mg to Si ranging from 2.0 to 4.0 for high strength alloys. The
ratio of Mg to Si may be selected to have a small solidification
temperature range (e.g. Scheil .DELTA.T.sub.80%-99% less than
60.degree. C.) such that the alloys may be suitable for the
additive manufacturing. The ratio of Mg to Si may also be selected
such that the Mg.sub.2Si particle volume % is equal to or greater
than 0.15 volume % such that the alloys may be in the desired
Mg--Si composition space and have the strength. The ratio of Mg to
Si may further be selected for good cosmetic appeal. In some
variations, the alloys can have reduced silicon (Si), for example,
ranging from 0.2 wt % to 3.0 wt %.
[0033] In some variations, the alloys can have
Mg.sub.2Si+AlFeSi+secondary phases less than or equal to 2 wt % of
the alloy. In some variations, the alloys can have
Mg.sub.2Si+AlFeSi+secondary phases less than or equal to 1.5 wt %
of the alloy. In some variations, the alloys can have
Mg.sub.2Si+AlFeSi+secondary phases less than or equal to 1.0 wt %
of the alloy. In some variations, the alloy can have not more than
1.5 vol % Mg.sub.2Si, not more than 1 vol % AlFeSi, and/or not more
than 0.5 vol % other secondary phases. In some additional
variations, the alloy can have not more than 4.0 vol %
Mg.sub.2Si+AlFeSi+secondary phases.
[0034] In some variations, the alloy can have not more than 1.5 vol
% Mg.sub.2Si. In some variations, the alloy can have not more than
1.0 vol % Mg.sub.2Si. In some variations, the alloy can have not
more than 0.5 vol % Mg.sub.2Si. In some variations, the alloy can
have not more than 1 vol % AlFeSi. In some variations, the alloy
can have not more than 0.8 vol % AlFeSi. In some variations, the
alloy can have not more than 0.6 vol % AlFeSi. In some variations,
the alloy can have not more than 0.4 vol % AlFeSi. In some
variations, the alloy can have not more than 0.5% other secondary
phases. In some variations, the alloy can have not more than 0.4%
other secondary phases. In some variations, the alloy can have not
more than 0.3% other secondary phases. In some variations, the
alloy can have not more than 0.2% other secondary phases. In some
additional variations, the alloy can have not more than 4 vol %
Mg.sub.2Si+AlFeSi+secondary phases. In some additional variations,
the alloy can have not more than 4.0 vol %
Mg.sub.2Si+AlFeSi+secondary phases. In some additional variations,
the alloy can have not more than 3.5 vol %
Mg.sub.2Si+AlFeSi+secondary phases. In some additional variations,
the alloy can have not more than 3.0 vol %
Mg.sub.2Si+AlFeSi+secondary phases. In some additional variations,
the alloy can have not more than 2.5 vol %
Mg.sub.2Si+AlFeSi+secondary phases. In some additional variations,
the alloy can have not more than 2.0 vol %
Mg.sub.2Si+AlFeSi+secondary phases. In some additional variations,
the alloy can have not more than 1.5 vol %
Mg.sub.2Si+AlFeSi+secondary phases. In some additional variations,
the alloy can have not more than 1.0 vol %
Mg.sub.2Si+AlFeSi+secondary phases.
[0035] To maintain cosmetic appeal, the alloys may have Fe less
than 0.35 wt %, or 0.15 wt %, e.g. a range from 0.04 wt % to 0.35
wt % or 0.04 wt % to 0.15 wt %, and the total of elements Cu, Mn,
Zn, Cr, and/or V may be less than 0.06 wt %.
[0036] In some variations, the alloys may have less than or equal
to 0.35 wt % Fe. In some variations, the alloys may have less than
or equal to 0.30 wt % Fe. In some variations, the alloys may have
less than or equal to 0.25 wt % Fe. In some variations, the alloys
may have less than or equal to 0.20 wt % Fe. In some variations,
the alloys may have less than or equal to 0.15 wt % Fe. In some
variations, the alloys may have less than or equal to 0.10 wt % Fe.
In some variations, the alloys may have less than or equal to 0.09
wt % Fe. In some variations, the alloys may have less than or equal
to 0.08 wt % Fe. In some variations, the alloys may have less than
or equal to 0.06 wt % Fe. Further, in some variations, the alloys
can have at least 0.02 wt % Fe. In some variations, the alloys can
have at least 0.04 wt % Fe. In some variations, the alloys can have
at least 0.06 wt % Fe.
[0037] In some variations, the total of elements Cu, Mn, Zn, Cr,
and/or V may be less than 0.15 wt %. In some variations, the total
of elements Cu, Mn, Zn, Cr, and/or V may be less than 0.10 wt %. In
some variations, the total of elements Cu, Mn, Zn, Cr, and/or V may
be less than 0.08 wt %. In some variations, the total of elements
Cu, Mn, Zn, Cr, and/or V may be less than 0.06 wt %. In some
variations, the total of elements Cu, Mn, Zn, Cr, and/or V may be
less than 0.04 wt %.
[0038] In various aspects, aluminum alloys described herein can
include a small amount of incidental impurities. The impurity
elements can be can be present, for example, as a byproduct of
processing and manufacturing. In various embodiments, an incidental
impurity can be no greater than 0.05 wt % of any one additional
element (i.e., a single impurity), and no greater than 0.10 wt %
total of all additional elements (i.e., total impurities).
[0039] I. Solidification
A. Solidification Temperature Range (.DELTA.T.sub.80%-99%)
[0040] The present aluminum alloys are processable when the
solidification temperature range (.DELTA.T.sub.80%-99%) is small.
The solidification temperature range is the temperature difference
between the solidus temperature and the Scheil temperature. In some
embodiments, the solidus temperature range can be
.DELTA.T.sub.80%-99%, where .DELTA.T.sub.80%-99% is the difference
between the temperature T.sub.99%, at which at least 99% of the
alloy is solidified, and the temperature T.sub.80%, at which at
least 80% of the alloy is solidified. In some variations, the
Scheil .DELTA.T.sub.80%-99% is less than 60.degree. C. In some
variations, the Scheil .DELTA.T.sub.80%-99% is less than 50.degree.
C. In some variations, the Scheil .DELTA.T.sub.80%-99% is less than
40.degree. C.
[0041] FIG. 1 depicts a predicted solidification diagram for
various alloys in accordance with the embodiments of the
disclosure. The prediction is obtained from a thermodynamic
modeling based on the CALPHAD (CALculation of PHAse Diagrams)
method, a branch of computational thermodynamics. In one
embodiment, CALPHAD method takes in readily available binary phase
diagrams (e.g. Al--Mg, Al--Si, Mg--Si, Al--Fe, Fe--Si) and
multi-component phase diagram (e.g. Al--Mg--Si--Fe) to make
prediction that is difficult to obtain experimentally. This method
enables computational prediction of material properties such as
solidification behavior.
[0042] As shown in FIG. 1, the solidification diagram includes a
horizontal axis representing the fraction of solids formed. The
solidification diagram also includes a vertical axis representing
temperature starting from liquidus temperature, at which the alloy
is in a liquid state, and ending at a solidus temperature or Scheil
temperature, at which the alloy is fully solidified. The liquidus
temperature is the equilibrium temperature above which the alloy is
completely liquid. The Scheil temperature is a non-equilibrium
solidus temperature, based on the Scheil approximation, at which
the alloy is predicted to completely solidify. The difference
between the Scheil temperature (non-equilibrium) and the solidus
temperature (equilibrium temperature) is referred to a
solidification temperature range, which is a processing window for
solution heat treatment in the completely solid state. Lower
solidification temperature range is more desirable for better
processability.
[0043] Solidification curves 110, 112, and 114 represent commercial
alloy 6063-T6, present Example Alloy 1, and commercial Al alloy
A356, respectively. Each solidification curve shows a solidus
temperature (equilibrium) versus fraction of solid from 0 to 1.0.
Turning to curve 110 representing commercial alloy 6063-T6, curve
110 starts from a liquid state at about 655.degree. C., and
solidifies in a small eutectic fraction region 104 at a solidus
temperature of about 557.degree. C. (also referred to a Scheil
temperature).
[0044] In some embodiments, the solidification temperature range
can be .DELTA.T.sub.80%-99%, where .DELTA.T.sub.80%-99% is defined
as the temperature T.sub.80%, at which at least 80% of the alloy is
solidified, subtracted by the temperature T.sub.99%, at which at
least 99% of the alloy is solidified. In some embodiments, the
alloy 6063-T6 has a solidification temperature range 116 which can
be represented by Scheil .DELTA..sub.0%-99% (the difference between
the liquidus temperature and the Scheil temperature).
[0045] Turning to solidification curve 112 representing Example
Alloy 1, Example Alloy 1 starts at a liquidus temperature of about
650.degree. C. and solidifies in a large eutectic fraction region
102 at a Scheil temperature of about 593.degree. C. Example Alloy 1
has a solidification temperature range 106 much smaller than that
of the commercial alloy 6063-T6.
[0046] Turning to curve 114 representing commercial alloy A356, the
alloy A356 starts at a liquidus temperature of about 615.degree.
C., and becomes solid at a Scheil temperature or solidus
temperature of about 538.degree. C. The solidification temperature
range 108 of commercial alloy A356 is lower than that of commercial
alloy 6063-T6. Further, commercial alloy A356 does not have any
eutectic fraction region like eutectic fraction region 102 for
Example Alloy 1 or an eutectic fraction region 104 the alloy
6063-T6.
[0047] Based on the solidification diagram as shown in FIG. 1,
liquidus temperatures, Scheil temperatures, and solidification
temperature ranges are provided for various alloys, and are listed
in Table 1. Table 1 also lists the alloy compositions, solvus
temperatures, and tensile yield strengths for various alloys. The
solvus temperature is the temperature at which all solid
precipitates (e.g. Mg.sub.2Si) dissolve into aluminum. Yield
strengths of the alloys may be determined per ASTM E8, which covers
the testing apparatus, test specimens, and testing procedure for
tensile testing.
TABLE-US-00001 TABLE 1 Composition and Properties of Processable
Aluminum Alloys in Comparison to Commercial Aluminum Alloys Yield
Liquidus Scheil Scheil Solvus Strength Alloy Mg Si Cu Fe T
(.degree. C.) T (.degree. C.) .DELTA.T.sub.80%-99% T (.degree. C.)
MPa A356-T6 0.3 7 0.2 0.2 615 538 24 >538 165 6063-T6 0.55 0.4 0
0.12 655 557 83 490 220 Example 1.5 0.44 0 0.08 650 593 33 580
>200 Alloy 1 Example 1.3 0.35 0 0.08 652 593 38 555 >200
Alloy 2 Example 1.3 0.35 0.1 0.08 652 581 49 557 >200 Alloy 3
Example 1.1 0.3 0 0.08 653 594 42 538 >200 Alloy 4
[0048] As shown in Table 1, Example Alloys 1-4 include higher Mg
content than commercial alloys A356 and 6063, and also lower Si
content than commercial Al alloy A356. The Al alloy may also
include a trace of copper (Cu), such as 0.1 wt % for Example Alloy
3.
[0049] The solidification temperature ranges of the present Al
alloys are comparable to that of the commercial Al alloy but
significantly lower than that of alloy 6063-T6. The Al alloys can
be processable or capable for additive manufacturing based on their
small solidification temperature ranges.
[0050] In some variations, the Al alloys also have low Scheil
.DELTA.T.sub.80%-99%, which can be comparable to that of commercial
alloy A356. Commercial Al alloy A356-T6 has a Scheil
.DELTA.T.sub.80%-99% of 24.degree. C., which is significantly
smaller than that of commercial Al alloy 6063-T6 (e.g. 83.degree.
C.). For example, Example Alloys 1-4 have .DELTA.T.sub.80%-99% of
33.degree. C., 38.degree. C., 49.degree. C., and 42.degree. C.,
respectively, which are comparable to that of commercial Al alloy
A356-T6. When .DELTA.T.sub.80%-99% is less than 60.degree. C., the
present Al alloys are suitable for additive manufacturing.
[0051] Scheil .DELTA.T.sub.80%-99% is better than Scheil
.DELTA.T.sub.0%-99%, because .DELTA.T.sub.80%-99% is consistently
small for the present alloys including Example Alloys 1-4. However,
.DELTA.T.sub.0%-99% was found to vary largely with Example Alloys
1-4. Example Alloys 1-4 have .DELTA.T.sub.80%-99% within 50.degree.
C., as shown in Table 1.
[0052] FIG. 2A depicts an example Mg--Si composition space with Mg
from 0.5 wt % to 2 wt % for compositions having various
solidification temperature ranges for Example Alloy 1 containing
0.08 wt % Fe in accordance with embodiments of the disclosure. As
shown, within composition space for Mg from 0.5 wt % to 2 wt % and
Si from 0.2 wt % to 1 wt %, curves 204 have various constant Scheil
.DELTA.T.sub.80%-99% ranges including 40.degree. C., 60.degree. C.,
80.degree. C., and 120.degree. C.
[0053] In some variations, the Mg--Si composition space 202 has a
ratio of Mg to Si ranging from 2.0 to 4.0. In some variations, the
Mg--Si composition space 202 has a ratio of Mg to Si ranging from
3.0 to 4.0. Turning to curve 204, when the Scheil
.DELTA.T.sub.80%-99% range is 40.degree. C., curve 204 has a
portion within the Mg--Si composition space 202. When the
.DELTA.T.sub.80%-99% range increases from 40.degree. C. to
60.degree. C., the portion of curve 204 completely shifts outside
the composition space 202. When the Scheil .DELTA.T.sub.80%-99%
range further increases to 80.degree. C. or 120.degree. C., curve
204 does not have any overlap with the composition space 202. Also,
Example Alloy 1 (labeled as 226) and Example Alloy 4 (labeled as
224) are within the composition space 202, while 6063 alloys
(labeled as 220 and 222) are outside the composition space 202. As
such, the Scheil .DELTA.T.sub.80%-99% should be less than
60.degree. C. for the present alloys to be processable or to be
able for additive manufacturing.
B. Solutionizing Temperature Window
[0054] In some variations, the Mg--Si composition may also be
limited by a solutionizing temperature window or solutionizing
window, which can be the difference between
1/2(T.sub.99%solid+T.sub.eq.solidus) and the solvus temperature
T.sub.solvus for Mg.sub.2Si. The solvus temperature is the
temperature at which all solid precipitates (e.g. Mg.sub.2Si)
dissolve into aluminum. For the Al alloys to be suitable for
additive manufacturing, such as 3D printing, the Al alloys need to
have the solutionizing temperature window greater than 20.degree.
C.
[0055] FIG. 2B depicts an example Mg--Si composition space with Mg
from 0.5 wt % to 2 wt % for compositions having various
solutionizing temperature ranges for Example Alloy 1 containing
0.08 wt % Fe in accordance with embodiments of the disclosure. As
shown, within composition space for Mg from 0.5 wt % to 2 wt % and
Si from 0.2 wt % to 1 wt %, curves 206 have various constant
solutionizing temperature ranges including 0.degree. C., 20.degree.
C., 40.degree. C., 60.degree. C., 80.degree. C., and 100.degree. C.
When the solutionizing temperature range increases, curve 206
shifts down toward the bottom left corner such that both Mg and Si
decreases. Also, Example Alloys 1 and 4 are within the composition
space 202, while 6063 alloys are outside the composition space 202.
When the solutionizing temperature range is 20.degree. C. or
higher, curves 206 have overlapping with composition space 202. As
such, the solutionizing temperature window is at least 20.degree.
C.
C. Critical Cooling Rate
[0056] The Al alloys can be cooled slowly enough to suppress
Mg.sub.2Si precipitation from quenching at a critical cooling rate.
The rates for quenching the Al alloys should be lower than the
critical cooling rate to suppress the Mg.sub.2Si precipitation. As
an example, the critical cooling rate for Mg.sub.2Si for Example
Alloy 1 is determined to be 82.degree. C./s, and T.sub.solvus, for
dissolving Mg.sub.2Si particles is determined to be 580.degree.
C.
[0057] FIG. 2C depicts an example Mg--Si composition space with Mg
from 0.5 wt % to 2 wt % for compositions having various critical
cooling rates for Example Alloy 1 containing 0.08 wt % Fe in
accordance with embodiments of the disclosure. As shown, within
composition space for Mg from 0.5 wt % to 2 wt % and Si from 0.2 wt
% to 1 wt %, curves 208 have various constant critical cooling
rates including 3.degree. C./s, 10.degree. C./s, 20.degree. C./s,
40.degree. C./s, 60.degree. C./s, and 80.degree. C./s. When the
critical cooling rate increases, curve 208 shifts up toward the
upper right corner such that both Mg and Si increase. Also, Example
Alloys 1 and 4 are within the composition space 202, while 6063
alloys are outside the composition space 202.
[0058] FIG. 2D depicts an overlapping composition space of Mg and
Si among Scheil .DELTA.T.sub.80%-99%, the solutionizing temperature
window, and critical cooling rate for Example Alloy 1 containing
0.08 wt % Fe in accordance with embodiments of the disclosure.
Example Alloy 1 does not include any impurity, such as Cu, Mn, Cr,
Zn, or V, among others.
[0059] As shown in FIG. 2D, inside a first composition space 210
having a first contour line 210A, the Scheil .DELTA.T.sub.80%-99%
is less than 60.degree. C. Also, inside a second composition space
212 having a second contour line 212A, the solutionizing
temperature window is greater than 20.degree. C. Further, inside a
third composition space 214 having a third contour line 214A, the
critical cooling rate is less than 80.degree. C./s. An overlapping
composition space 216 for the first, second, and third composition
space 210, 212, and 214 can meet all three requirements including
(1) Scheil .DELTA.T.sub.80%-99% less than 60.degree. C., (2)
solutionizing temperature window greater than 20.degree. C., and
(3) a critical cooling rate less than 80.degree. C./s. The
overlapping composition space has Mg up to about 1.6 and Si up to
0.5.
[0060] In some embodiments, the Al alloy may include 0.5 wt % to
1.6 wt % Mg. In some embodiments, the Al alloy may include 0.2 wt %
to 0.5 wt % Si.
[0061] In some embodiments, the Al alloy may include equal to or
less than 1.6 wt % Mg. In some embodiments, the Al alloy may
include equal to or less than 1.4 wt % Mg. In some embodiments, the
Al alloy may include equal to or less than 1.2 wt % Mg. In some
embodiments, the Al alloy may include equal to or less than 1.0 wt
% Mg. In some embodiments, the Al alloy may include equal to or
less than 0.8 wt % Mg. In some embodiments, the Al alloy may
include equal to or less than 0.6 wt % Mg. In some embodiments, the
Al alloy may include at least 0.5 wt % Mg. In some embodiments, the
Al alloy may include at least 0.7 wt % Mg. In some embodiments, the
Al alloy may include at least 0.9 wt % Mg. In some embodiments, the
Al alloy may include at least 1.1 wt % Mg. In some embodiments, the
Al alloy may include at least 1.3 wt % Mg. In some embodiments, the
Al alloy may include at least 1.5 wt % Mg.
[0062] In some embodiments, the Al alloy may include equal to or
less than 0.5 wt % Si. In some embodiments, the Al alloy may
include equal to or less than 0.4 wt % Si. In some embodiments, the
Al alloy may include at least 0.2 wt % Si. In some embodiments, the
Al alloy may include at least 0.3 wt % Si. In some embodiments, the
Al alloy may include at least 0.4 wt % Si.
D. Large Eutectic Fraction Region
[0063] In various aspects, the alloys have large eutectic fraction
regions. The eutectic fraction is a fraction range of solid formed
at a constant temperature. In various aspects, the alloys are not
susceptible to hot tearing because the alloys have a large eutectic
fraction, e.g. the alloy has a large fraction of liquid to solidify
into solid at a constant temperature. In eutectic fraction regions
102 or 104, liquid solidifies into solid at a constant temperature
such that no contraction can be induced from any temperature change
and the contraction is only induced by transformation from liquid
to solid.
[0064] However, commercial alloy A356 does not have the same kind
of eutectic region as Example Alloy 1. The eutectic fraction/region
of commercial alloy A356 starts to form at about 90% solid, but it
tapers down after that the eutectic fraction/region. Alloy A356
does not hot crack, because silicon has a higher molar volume than
aluminum when silicon comes out from the liquid so the newly formed
silicon actually expands and helps counter the thermal stress that
causes hot cracking.
[0065] In various aspects, the alloys can have a large eutectic
fraction region to reduce or prevent likelihood of hot tearing.
Unlike commercial alloy 6063, which has a very small eutectic
fraction region (an eutectic fraction of about 1-2%), Example Alloy
1 has a large eutectic fraction region (an eutectic fraction of
about 10%).
[0066] In some aspects, the alloys can have a eutectic fraction of
at least 5%. In some embodiments, the alloys can have an eutectic
fraction of at least 6%. In some embodiments, the alloys can have
an eutectic fraction of at least 7%. In some embodiments, the
alloys can have an eutectic fraction of at least 8%. In some
embodiments, the alloys can have an eutectic fraction of at least
9%. In some embodiments, the alloys can have an eutectic fraction
of at least 10%.
E. Scheil Temperature Greater than T.sub.solvus for Mg.sub.2Si
[0067] In some variations, Mg may have an upper limit determined by
the solvus temperature that does not exceed the Scheil temperature.
Referring again to Table 1, the solvus temperature increases from
1.1 wt % to 1.5 wt % as the Mg content increased from 538.degree.
C. to 580.degree. C. The solvus temperature may continue to
increase with Mg content until the solvus temperature equals to the
Scheil temperature for the alloy.
[0068] The Mg.sub.2Si particles can be dissolved to leave a more
homogeneous structure, which is more suitable for anodizing.
[0069] Homogenization or solution treatment may be used to achieve
a homogeneous structure, which helps obtain a better anodized
surface finish. The heat treatment dissolves Mg.sub.2Si particles,
which requires that the solvus temperature is lower than the Scheil
temperature. The maximum Mg content may be limited by the heat
treatment of the alloy. Without wishing to be limited to a
mechanism or mode of action, the Mg can form an eutectic fraction
with the aluminum matrix and Mg.sub.2Si is dissolved completely in
the aluminum matrix.
[0070] Commercial alloys A356 and A383 are more easily processed
(e.g., by additive manufacturing), mainly due to their high Si
content. However, when commercial alloy A356 has silicon solvus
temperature (.about.570.degree. C.) and Mg.sub.2Si solvus
temperature (.about.557.degree. C.) greater than the Scheil
temperature, the alloy cannot be heat treated to form a homogeneous
structure.
In some embodiments, the alloy may include an overall amount Mg
ranging from 1.0 wt % to 3.0 wt %. In some embodiments, the alloy
may include Mg less than 3.0 wt %. In some embodiments, the alloy
may include Mg less than 2.5 wt %. In some embodiments, the alloy
may include Mg less than 2.0 wt %. In some embodiments, the alloy
may include Mg less than 1.5 wt %. In some embodiments, the alloy
includes Mg greater than 1.0 wt %. In some embodiments, the alloy
includes Mg greater than 1.5 wt %. In some embodiments, the alloy
includes Mg greater than 2.0 wt %. In some embodiments, the alloy
includes Mg greater than 2.5 wt %.
[0071] II. High Tensile Strength-Mg.sub.2Si Particles
[0072] Mg.sub.2Si particles or precipitates can strengthen the
alloy. Mg.sub.2Si particles or precipitates can be formed and
distributed in the aluminum to strengthen the alloy. The excess Mg
not incorporated into the Mg.sub.2Si particles or precipitates can
be distributed in the Al matrix to further strengthen the
alloy.
[0073] In various embodiments, the higher Mg content of the alloys
results in all Si precipitating within the Al matrix in the form of
Mg.sub.2Si particles. The Mg in excess of the stoichiometric amount
is included within the Al matrix, which results in alloys
possessing high yield strength and smooth anodizable finish
comparable to commercial 6000 alloys while simultaneously
possessing additive manufacturability characteristics comparable to
commercial Al alloys such as A356 or A383.
[0074] As depicted in Table 1, Example Alloys 1-4 have higher Mg
content (e.g. 1.5 wt %, 1.3 wt %, or 1.1 wt %) than that of
commercial Al alloy 6063-T6 (e.g. 0.55 wt %), which may result in
higher predicted yield strengths (>200 MPa for alloys vs 210 MPa
for commercial alloy 6063-T6).
[0075] Mg.sub.2Si may be formed as discrete particles and/or linked
particles. Various heat treatments can be used to guide the
formation of Mg.sub.2Si as discrete particles, rather than linked
particles. Discrete particles can result in better strengthening
than linked particles. The size of the Mg.sub.2Si particles can
depend on one or more of at least several variables including, but
not limited to, the aging temperatures and aging times used in the
aging process, the concentration of Mg in excess of the
stoichiometric amount within the Al matrix, the wt % of Mg.sub.2Si
within the Al matrix, and the presence and/or concentration of
additional alloying atoms such as Cr, Mn, and/or Sc. In various
embodiments, Mg.sub.2Si can be re-precipitated during the aging
step.
[0076] FIG. 4 depicts an example Mg--Si composition space with Mg
up to 2 wt % for compositions having various tensile strengths for
Example Alloy 1 containing 0.08 wt % Fe in accordance with
embodiments of the disclosure. As shown, within composition space
for Mg from 0.5 wt % to 2 wt % and Si from 0.2 wt % to 1 wt %,
curves 402 have various constant tensile strengths including 200
MPa, 220 MPa, 240 MPa, 260 MPa, 280 MPa, and 300 MPa. When the
tensile strength increases, curve 404 shifts to the right bottom
corner, such that Mg decreases and Si increases. Also, Example
Alloys 1 and 4 are within the composition space 202 having a range
of Mg to Si ratios, while 6063 alloys are outside the composition
space 202. When the tensile strength is 220 MPa, curve 402 overlaps
with composition space 202.
Mg:Si Ratio
[0077] In some embodiments, the net weight ratio of Mg:Si ranges
from 2 to 4.0, including Mg.sub.2Si particles and Mg in the Al
alloy matrix. In other embodiments, the overall weight ratio of
Mg:Si may be at least 2. In other embodiments, the overall weight
ratio of Mg:Si may be at least 2.2. In other embodiments, the
overall weight ratio of Mg:Si may be at least 2.4. In other
embodiments, the overall weight ratio of Mg:Si may be at least 2.6.
In other embodiments, the overall weight ratio of Mg:Si may be at
least 2.8. In other embodiments, the overall weight ratio of Mg:Si
may be at least 3.0. In other embodiments, the overall weight ratio
of Mg:Si may be at least 3.2. In other embodiments, the overall
weight ratio of Mg:Si may be at least 3.4. In other embodiments,
the overall weight ratio of Mg:Si may be at least 3.6. In other
embodiments, the overall weight ratio of Mg:Si may be at least 3.7.
In other embodiments, the overall weight ratio of Mg:Si may be at
least 3.8. In other embodiments, the overall weight ratio of Mg:Si
may be at least 3.9.
[0078] In other embodiments, the overall weight ratio of Mg:Si may
be less than 4.0. In other embodiments, the overall weight ratio of
Mg:Si may be less than 3.9. In other embodiments, the overall
weight ratio of Mg:Si may be less than 3.8. In other embodiments,
the overall weight ratio of Mg:Si may be less than 3.7. In other
embodiments, the overall weight ratio of Mg:Si may be less than
3.6. In other embodiments, the overall weight ratio of Mg:Si may be
less than 3.4. In other embodiments, the overall weight ratio of
Mg:Si may be less than 3.2. In other embodiments, the overall
weight ratio of Mg:Si may be less than 3. In other embodiments, the
overall weight ratio of Mg:Si may be less than 2.8. In other
embodiments, the overall weight ratio of Mg:Si may be less than
2.6. In other embodiments, the overall weight ratio of Mg:Si may be
less than 2.4. In other embodiments, the overall weight ratio of
Mg:Si may be less than 2.2.
Mg.sub.2Si Phase Volume
[0079] The tensile strength increases with Mg.sub.2Si constituent
phase. FIG. 5 depicts an example Mg--Si composition space with Mg
from 0.5 wt % to 2 wt % for compositions having various Mg.sub.2Si
secondary phase for Example Alloy 1 containing 0.08 wt % Fe in
accordance with embodiments of the disclosure. As shown, within
composition space for Mg from 0.5 wt % to 2 wt % and Si from 0.2 wt
% to 1 wt %, curves 502 have various constant Mg.sub.2Si
constituent phases vol % including 0.15 vol %, 0.20 vol %, 0.25 vol
%, 0.50 vol %, 0.75 vol %, 1.00 vol %, and 1.25 vol %. When the
Mg.sub.2Si constituent phase increases, curve 502 shifts toward the
upper right corner, such that both Mg and Si increase. Also,
Example Alloys 1 and 4 are within the composition space 202 having
a range of Mg to Si ratios, while 6063 alloys are outside the
composition space 202. When the Mg.sub.2Si constituent phase has
0.15 vol %, curves 502 overlap with the composition space 202.
[0080] For the alloys, the Mg.sub.2Si phase may be present both
within the grains and at the grain boundary. The Mg.sub.2Si phase
may constitute about 0.15 vol % to about 6 vol % of the alloys. In
some embodiments, the Mg.sub.2Si phase includes greater than 0.15
vol % of the alloys. In some embodiments, the Mg.sub.2Si phase
includes greater than 0.25 vol % of the alloys. In some
embodiments, the Mg.sub.2Si phase includes greater than 0.35 vol %
of the alloys. In some embodiments, the Mg.sub.2Si phase includes
greater than 0.5 vol % of the alloys. In some embodiments, the
Mg.sub.2Si phase includes greater than 1.0 vol % of the alloys. In
some embodiments, the Mg.sub.2Si phase includes greater than 2.0
vol % of the alloys. In some embodiments, the Mg.sub.2Si phase
includes greater than 3.0 vol % of the alloys. In some embodiments,
the Mg.sub.2Si phase includes greater than 4.0 vol % of the alloys.
In some embodiments, the Mg.sub.2Si phase includes greater than 5.0
vol % of the alloys.
[0081] In some embodiments, the Mg.sub.2Si phase includes less than
6.0 vol % of the alloys. In some embodiments, the Mg.sub.2Si phase
includes less than 5 vol % of the alloys. In some embodiments, the
Mg.sub.2Si phase includes less than 4 vol % of the alloys. In some
embodiments, the Mg.sub.2Si phase includes less than 3 vol % of the
alloys. In some embodiments, the Mg.sub.2Si phase includes less
than 2 vol % of the alloys. In some embodiments, the Mg.sub.2Si
phase includes less than 1 vol % of the alloys. In some
embodiments, the Mg.sub.2Si phase includes less than 0.5 vol % of
the alloys. In some embodiments, the Mg.sub.2Si phase includes less
than 0.35 vol % of the alloys. In some embodiments, the Mg.sub.2Si
phase includes less than 0.25 vol % of the alloys.
[0082] In various other aspects, the alloy may include up to about
2 wt % of Mg in excess of the stoichiometric amount of Mg.sub.2Si.
In various other aspects, the alloy may include up to about 1.8 wt
% of Mg in excess of a stoichiometric amount. In various other
aspects, the alloy may include up to about 1.6 wt % of Mg in excess
of a stoichiometric amount. In various other aspects, the alloy may
include up to about 1.4 wt % of Mg in excess of a stoichiometric
amount. In various other aspects, the alloy may include up to about
1.2 wt % of Mg in excess of a stoichiometric amount. In various
other aspects, the alloy may include up to about 1.4 wt % of Mg in
excess of a stoichiometric amount. In various other aspects, the
alloy may include up to about 1 wt % of Mg in excess of a
stoichiometric amount. In various other aspects, the alloy may
include up to about 0.8 wt % of Mg in excess of a stoichiometric
amount. In various other aspects, the alloy may include up to about
0.7 wt % of Mg in excess of a stoichiometric amount. In various
other aspects, the alloy may include up to about 0.5 wt % of Mg in
excess of a stoichiometric amount. In various other aspects, the
alloy may include up to about 0.3 wt % of Mg in excess of a
stoichiometric amount. In various other aspects, the alloy may
include up to about 0.1 wt % of Mg in excess of a stoichiometric
amount. In various other aspects, the alloy may greater than about
0.3 wt % of Mg in excess of a stoichiometric amount. In various
other aspects, the alloy may greater than about 0.5 wt % of Mg in
excess of a stoichiometric amount. In various other aspects, the
alloy may greater than about 0.7 wt % of Mg in excess of a
stoichiometric amount.
[0083] III. Cosmetic Appeal
[0084] The present alloys may also have Scheil temperature lower
than the solidus temperature such that the alloys may be heat
treatable and can result in a cosmetically appealing anodized
surface finish. When the solidus temperature is lower than the
Scheil temperature, the magnesium silicide (Mg.sub.2Si) particles
or precipitates can be dissolved to form homogeneous
microstructures. As such, the alloys can have a cosmetically
attractive anodized surface finish.
[0085] In one embodiment, Example Alloy 1 includes 1.5 wt % Mg,
0.44 wt % Si, has a solvus temperature of 580.degree. C., and has a
Scheil temperature of 593.degree. C. In this case, Example Alloy 1
has the solvus temperature smaller than the Scheil temperature, so
that Example Alloy 1 may be heat treatable, which can result in an
appealing anodized surface finish.
[0086] In another embodiment, Example Alloy 2 includes 1.3 wt % Mg,
0.35 wt % Si, has a solvus temperature of 555.degree. C., and has a
Scheil temperature of 593.degree. C. Comparing Example Alloy 1 with
Example Alloy 2, the solvus temperatures drops for about 25.degree.
C. with the Mg content changing from 1.5 wt % to 1.3 wt %. Again,
the solvus temperature is smaller than the Scheil temperature for
Example Alloy 2, so that Example Alloy 2 may be heat treatable,
which may result in an appealing anodized surface finish.
[0087] In yet another embodiment, Example Alloy 3 of the disclosure
includes 1.3 wt % Mg, 0.35 wt % Si, 0.1 wt % Cu, has a solvus
temperature of 557.degree. C., and has a Scheil temperature of
581.degree. C. Again, the solvus temperature is smaller than the
Scheil temperature for Example Alloy 3, so that Example Alloy 3 may
be heat treatable, which may result in an appealing anodized
surface finish.
[0088] In still yet another embodiment, Example Alloy 3 of the
disclosure includes 1.3 wt % Mg, 0.35 wt % Si, 0.1 wt % Cu, has a
solvus temperature of 538.degree. C., and has a Scheil temperature
of 594.degree. C. Comparing Example Alloy 2 with Example Alloy 4,
the solvus temperatures drops for about 20.degree. C. with the Mg
content reducing from 1.3 wt % to 1.1 wt %. Again, the solvus
temperature is smaller than the Scheil temperature for Example
Alloy 4, so that Example Alloy 4 may be heat treatable, which may
result in an appealing anodized surface finish.
Si Content
[0089] The alloys in various embodiments can have a cosmetically
appealing surface after being anodized. The present alloys have
relatively low Si content. The Si content in the disclosed alloys
is lower than commercial aluminum alloys. Without the high Si
content of the A356 and A383 commercial Al alloys is thought to
impart good fluidity and hot cracking resistance to these
commercial alloys. In various aspects, the alloys can be designed
to be additive manufacturable without need for excess Si content,
because the alloys have a small solidification temperature range,
similar to the solidification temperature range of commercial Al
alloy A356-T6.
[0090] The commercial Al alloys A356 and A383 can produce an
undesirable microstructure, which makes the alloy have a poor color
response to anodizing. The presence of silicon particles may result
in a dull and dark anodized finish.
[0091] Low Si content (e.g. 1.0 wt % or below) in the alloy may
also help increase the amount of Mg to be dissolved and thus
increase the yield strength of the alloy.
[0092] For example, dull and dark anodized finish or yellowish
anodized finish does not have cosmetic appeal. In contrast, good or
great cosmetic appeal substantially eliminates the dull, dark or
yellowish anodized finish.
[0093] In some embodiments, the alloy includes Si ranging from 0.2
wt % to 3.0 wt %. In some embodiments, the alloy includes Si less
than 3.0 wt %. In some embodiments, the alloy includes Si less than
2.5 wt %. In some embodiments, the alloy includes Si less than 2.0
wt %. In some embodiments, the alloy includes Si less than 1.5 wt
%. In some embodiments, the alloy includes Si less than 1.0 wt %.
In some embodiments, the alloy includes Si less than 0.9 wt %. In
some embodiments, the alloy includes Si less than 0.8 wt %. In some
embodiments, the alloy includes Si less than 0.7 wt %. In some
embodiments, the alloy includes Si less than 0.6 wt %. In some
embodiments, the alloy includes Si less than 0.5 wt %. In some
embodiments, the alloy includes Si less than 0.4 wt %. In some
embodiments, the alloy includes Si less than 0.3 wt %.
[0094] In some embodiments, the alloy includes Si greater than 0.2
wt %. In some embodiments, the alloy includes Si greater than 0.3
wt %. In some embodiments, the alloy includes Si greater than 0.4
wt %. In some embodiments, the alloy includes Si greater than 0.5
wt %. In some embodiments, the alloy includes Si greater than 0.6
wt %. In some embodiments, the alloy includes Si greater than 0.7
wt %. In some embodiments, the alloy includes Si greater than 0.8
wt %. In some embodiments, the alloy includes Si greater than 0.9
wt %. In some embodiments, the alloy includes Si greater than 0.9
wt %. In some embodiments, the alloy includes Si greater than 0.9
wt %. In some embodiments, the alloy includes Si greater than 0.9
wt %. In some embodiments, the alloy includes Si greater than 0.9
wt %. In some embodiments, the alloy includes Si greater than 0.9
wt %. In some embodiments, the alloy includes Si greater than 0.9
wt %. In some embodiments, the alloy includes Si greater than 0.9
wt %. In some embodiments, the alloy includes Si greater than 1 wt
%. In some embodiments, the alloy includes Si greater than 1.2 wt
%. In some embodiments, the alloy includes Si greater than 1.4 wt
%. In some embodiments, the alloy includes Si greater than 1.6 wt
%. In some embodiments, the alloy includes Si greater than 1.8 wt
%. In some embodiments, the alloy includes Si greater than 2.0 wt
%. In some embodiments, the alloy includes Si greater than 2.2 wt
%. In some embodiments, the alloy includes Si greater than 2.4 wt
%. In some embodiments, the alloy includes Si greater than 2.6 wt
%. In some embodiments, the alloy includes Si greater than 2.8 wt
%. In some embodiments, the alloy includes Si greater than 2.9 wt
%.
[0095] The present alloys typically do not include Mn, as Mn may
negatively impact the brightness and/or color of an anodized finish
of the alloys.
Fe Content and Impurity
[0096] Additionally, the alloys can have lower iron (Fe) content
than commercial alloys. Commercial alloys generally include 0.2 wt
% to 0.5 wt % Fe. However, the presence of Fe may make the alloy
look darker.
[0097] FIG. 6 depicts an example Fe vs. impurity (including Cu, Mn,
Cr, Zn, and or V) composition space with Fe up to 0.25 wt % and
individual impurity up to 0.1% for an Example Alloy having various
Mg.sub.2Si secondary phases in accordance with embodiments of the
disclosure. As shown, region 602 provides the alloys with a
desirable cosmetic appeal (index 0.6) for Example alloys containing
0.44 wt % Si, 1.5 wt % Mg. The curves 604 correspond to various
cosmetic appeal indexes including 0.6, 0.7, 0.8, 0.9, 1.0, and 1.1.
As shown, the cosmetic appeal index becomes worse with increased Fe
or impurity including Cu, Mn, Cr, Zn, and/or V. The alloys may have
up to 0.15 wt % Fe and 0.055 wt % impurity including one or more
elements Cu, Mn, Cr, Zn, or V.
[0098] In some embodiments, the alloy can be designed to have lower
Fe content from 0.04 wt % to 0.15 wt %.
[0099] An Fe content of at least 0.04 wt % may help form fine grain
structure to strengthen the alloy. In other embodiments, the alloy
may include Fe in an amount of at least 0.04 wt %, at least 0.06 wt
%, at least 0.08 wt %, at least 0.1 wt %, or at least 0.11 wt %. In
other embodiments, the alloy may include Fe in an amount less than
0.15 wt %, 0.14 wt %, 0.13 wt %, 0.12 wt %, less than 0.1 wt %,
less than 0.09 wt %, less than 0.08 wt %, less than 0.07 wt %, less
than 0.06 wt %, or less than 0.05 wt %.
[0100] In some embodiments, the impurity in the alloys may be less
than or equal to 0.06 wt %. In some embodiments, the impurity in
the alloys may be less than or equal to 0.05 wt %. In some
embodiments, the impurity in the alloys may be less than or equal
to 0.04 wt %. In some embodiments, the impurity in the alloys may
be less than or equal to 0.03 wt %. In some embodiments, the
impurity in the alloys may be less than or equal to 0.02 wt %.
Grain Size
[0101] An additional metal, selected from Zr, Cr, Mn, Sc, and/or
any combination thereof, may be included in the alloy to aid in the
control of grain size within the alloy during heat treatment. In
one embodiment, the additional metal may be Zr. In another
embodiment, the additional metal may be Cr. In another embodiment,
the additional metal may be Mn. In another embodiment, the
additional metal may be Sc. The additional metal may be included in
an amount of less than 0.5 wt % in various embodiments. In other
embodiments, the amount of additional metal may be less than 0.4 wt
%. In other embodiments, the amount of additional metal may be less
than 0.3 wt %. In other embodiments, the amount of additional metal
may be less than 0.2 wt %. In other embodiments, the amount of
additional metal may be less than 0.1 wt %.
[0102] In other embodiments, the amount of additional metal may be
greater than 0.1 wt %. In other embodiments, the amount of
additional metal may be greater than 0.2 wt %. In other
embodiments, the amount of additional metal may be greater than 0.3
wt %. In other embodiments, the amount of additional metal may be
greater than 0.4 wt %.
[0103] In some embodiments, the additional metal is Zr in an amount
of at least 0.10 wt % of the total alloy. In other embodiments, the
additional metal is Zr at least 0.12 wt % of the total alloy. In
other embodiments, the additional metal is Zr at least 0.14 wt % of
the total alloy. In other embodiments, the additional metal is Zr
at least 0.16 wt % of the total alloy. In other embodiments, the
additional metal is Zr at least 0.18 wt % of the total alloy. In
other embodiments, the additional metal is Zr less or equal to 0.20
wt % of the total alloy. In other embodiments, the additional metal
is Zr less or equal to 0.18 wt % of the total alloy. In other
embodiments, the additional metal is Zr less or equal to 0.16 wt %
of the total alloy. In other embodiments, the additional metal is
Zr less or equal to 0.14 wt % of the total alloy. In other
embodiments, the additional metal is Zr less or equal to 0.12 wt %
of the total alloy.
Anodizing, Blasting, and Coloring
[0104] The present alloys can be anodized and blasted to have a
cosmetically appealing surface finish as designed.
[0105] Anodizing is a surface treatment process for metal, most
commonly used to protect aluminum alloys. Anodizing uses
electrolytic passivation to increase the thickness of the natural
oxide layer on the surface of metal parts.
[0106] The anodized layer is thin (e.g. less than 1 .mu.m) for
commercial alloys A356 or A383. In this example, the alloy contains
10 wt % Si. The anodized layer may include numerous
discontinuities, where the Al.sub.2O.sub.3 layer has nearly zero
thickness.
[0107] To achieve an appealing anodized surface finish, the
anodized layer using the present alloys can be designed to have a
thickness of at least 6 .mu.m, and the anodized layer can be
designed to have a continuous microstructure, rather than
discontinuous microstructure.
[0108] In some embodiments, the present alloys can form enclosures
for electronic devices. The enclosures can be designed to have a
blasted surface finish, or an absence of streaky lines. Blasting is
a surface finishing process, for example, smooth a rough surface or
roughen a smooth surface. Blasting can remove surface materials by
forcibly propelling a stream of abrasive material against a surface
under high pressure.
[0109] In some embodiments, the alloys can be anodized to have a
neutral color. The alloys can also be dyed into any desirable
color.
[0110] Standard methods can be used to evaluate cosmetic appeal
including color, gloss and haze. The color of objects may be
determined by the wavelength of light that is reflected or
transmitted without being absorbed assuming incident light is white
light. The visual appearance of objects may vary with light
reflection or transmission. Additional appearance attributes may be
based on the directional brightness distribution of reflected light
or transmitted light, commonly referred to glossy, shiny, dull,
clear, haze, among others. The quantitative evaluation may be
performed based on ASTM Standards on Color & Appearance
Measurement, ASTM E-430 Standard Test Methods for Measurement of
Gloss of High-Gloss Surfaces, including ASTM D523 (Gloss), ASTM
D2457 (Gloss on plastics), ASTM E430 (Gloss on high-gloss surfaces,
haze), and ASTM D5767 (DOI), among others. The measurements of
gloss, haze, and DOI may be performed by testing equipment, such as
Rhopoint IQ.
[0111] In some embodiments, color can be quantified by parameters
L, a, and b, where L stands for light brightness, a stands for
color between red and green, and b stands for color between blue
and yellow. For example, high b values suggest an unappealing
yellowish color, not a gold yellow color. Nearly zero parameters a
and b suggest a neutral color. Low L values suggest dark
brightness, while high L values suggest great brightness. For color
measurement, testing equipment, such as X-Rite ColorEye XTH, X-Rite
Coloreye 7000 may be used. These measurements are according to
CIE/ISO standards for illuminants, observers, and the L* a* b*
color scale. For example, the standards include: (a) ISO
11664-1:2007(E)/CIE S 014-1/E:2006: Joint ISO/CIE Standard:
Colorimetry--Part 1: CIE Standard Colorimetric Observers; (b) ISO
11664-2:2007(E)/CIE S 014-2/E:2006: Joint ISO/CIE Standard:
Colorimetry--Part 2: CIE Standard Illuminants for Colorimetry, (c)
ISO 11664-3:2012(E)/CIE S 014-3/E:2011: Joint ISO/CIE Standard:
Colorimetry--Part 3: CIE Tristimulus Values; and (d) ISO
11664-4:2008(E)/CIE S 014-4/E:2007: Joint ISO/CIE Standard:
Colorimetry--Part 4: CIE 1976 L* a* b* Color Space.
EXAMPLES
[0112] FIG. 3A depicts an example composition space with Mg from
0.5 wt % to 3 wt % and Si from 0.2 wt % to 1.0 wt % for
compositions having various Scheil temperatures and solvus
temperatures in accordance with embodiments of the disclosure. As
shown, curves 306A-E represent the constant Scheil temperatures,
450.degree. C., 500.degree. C., 550.degree. C., 570.degree. C., and
590.degree. C., respectively. Curves 408A-F represent constant
solvus temperatures 590.degree. C., 570.degree. C., 550.degree. C.,
530.degree. C., 510.degree. C., and 490.degree. C., respectively.
In region 302, the solvus temperature of Mg.sub.2Si is lower than
the Scheil temperature such that the alloy can be heat treated to
obtain a cosmetically attractive anodized finish. The solvus
temperature obtained from FIG. 3A is also listed in Table 1.
[0113] FIG. 3B depicts an example composition space with Mg from
0.5 wt % to 3 wt % and Si from 0.2 wt % to 1.0 wt % for
compositions having various solidification temperature ranges in
accordance with embodiments of the disclosure. As shown in FIG. 3B,
curves 314A-E represent solidification temperature ranges
180.degree. C., 140.degree. C., 100.degree. C., 80.degree. C., and
60.degree. C., respectively. Region 310 is within a solidification
temperature range of 60.degree. C., and region 316 is within a
solidification temperature range of 80.degree. C. As disclosed
herein, the solidification temperature range is the difference
between the solidus temperature and the Scheil temperature. There
is an overlapping region between region 310 and region 316. The
alloys can have greater processablity or additive manufacturability
in region 310 than in the non-overlapping region within region 316,
but outside region 310.
[0114] As shown in FIG. 3B, Example Alloys 5 (Al-1.2Mg-0.3Si) and 6
(Al-1.5Mg-0.4Si) are within the "great cosmetic appeal" region in
which the alloys can have greater additive manufacturability and
cosmetic appeal than other regions. Example Alloy 7
(Al-1.9Mg-0.55Si) can have greater additive manufacturability than
other regions and have the cosmetic appeal not as good as Example
Alloys 5-6, but still has "good cosmetic appeal". The "great
cosmetic appeal" region also covers the composition space of both
alloys 6063 and 6061.
[0115] As disclosed herein, the alloys can have a cosmetically
attractive anodized finish in region 302, and can have better
additive manufacturability in region 310. In an overlapping region
312 between region 310 and region 302, the alloys can have better
additive manufacturability and better cosmetically attractive
anodized finish than other regions.
[0116] Within the non-overlapping region between region 312 and
region 302, the alloys can have better additive manufacturability
than any other regions. The alloys can also have less cosmetically
attractive anodized finish in the non-overlapping region than the
region 312, because the solidification temperature range for the
non-overlapping region is 80.degree. C. in the non-overlapping
region, higher than a solidification temperature range of
60.degree. C. of region 312. Lower solidification temperature range
is more desirable for better additive manufacturability.
[0117] Region 316 bounded by dashed lines 314D is within
solidification temperature range 80.degree. C. Within region 316
but outside region 310 and outside region 302, the alloys can have
less additive manufacturability than region 310 and less
cosmetically attractive anodized finish than region 302.
[0118] FIG. 3C depicts an example composition space with Mg from
0.5 wt % to 8 wt % and Si from 0.2 wt % to 3 wt % for compositions
having various solidification temperature ranges in accordance with
embodiments of the disclosure. As shown, curves 314A-D represent
solidification temperature ranges 180.degree. C., 140.degree. C.,
100.degree. C. and 60.degree. C., respectively. Region 310 is
bounded by curve 314D, i.e. solidification temperature range
60.degree. C. Region 310 includes Mg from about 1.4 wt % to about 7
wt %, Si from about 0.4 wt % to 3 wt %. If the solidification
temperature range becomes 80.degree. C., the Mg and Si ranges may
vary. For example, the Si may be as low as 0.2 wt % and Mg may be
as low as 1.0 wt %. The weight ratio of Mg to Si can vary from
about 2 to about 3 based on curves 314D and 314E for solidification
temperature ranges of 80.degree. C. and 60.degree. C. Example Alloy
8 (Al-3.5Mg-1.2Si) can have greater additive manufacturability than
other regions and have a cosmetic appeal less than Example Alloys
5-6, but still has "good cosmetic appeal."
[0119] In some aspects, the total of one or more of elements Cu, Cr
and Mn may not exceed a threshold total quantity. In some
embodiments, the total of one or more of elements Cu, Cr, and Mn is
equal to or less than 0.1 wt %. In some embodiments, the total of
one or more of elements Cu, Cr, and Mn is equal to or less than
0.08 wt %. In some embodiments, the total of one or more of
elements Cu, Cr, and Mn is equal to or less than 0.06 wt %. In some
embodiments, the total of one or more of elements Cu, Cr, and Mn is
equal to or less than 0.04 wt %. In some embodiments, the total of
one or more of elements Cu, Cr, and Mn is equal to or less than
0.02 wt %.
[0120] In some aspects, the Al alloys can include a small amount of
incidental impurities. The impurity elements can be can be present,
for example, as a byproduct of processing and manufacturing. The
impurities can be less than or equal to about 2 wt %, alternatively
less than or equal about 1 wt %, alternatively less than or equal
about 0.5 wt %, alternatively less than or equal about 0.1 wt
%.
[0121] IV. Additive Manufacturing
[0122] Additive Manufacturing (AM) technologies provide methods for
building three dimensional (3D) objects by adding layer-upon-layer
of material. The material includes metal or plastic among others.
One of the common to AM technologies is the use of a computer, 3D
modeling software such as Computer Aided Design (CAD), machine
equipment and layering material. Once a CAD sketch is produced, the
AM equipment reads in data from the CAD file and lays downs or adds
successive layers of liquid, powder, sheet material or other, in a
layer-upon-layer fashion to fabricate a 3D object.
[0123] The AM encompasses many technologies including subsets like
3D Printing, Rapid Prototyping, Direct Digital Manufacturing (DDM),
layered manufacturing and additive fabrication.
[0124] The early use of AM in the form of Rapid Prototyping focused
on preproduction visualization models. More recently, the AM is
being used to fabricate end-use products.
[0125] In some embodiments, the alloys can be atomized to form a
powder. Atomization is accomplished by forcing a molten metal
stream through an orifice at moderate pressures. The atomized
powder can be locally heated by using laser or electron beam.
[0126] The present alloys can be used for additive manufacturing
(e.g., 3D printing), which constructs a part from a powder layer by
layer. During additive manufacturing, the powder can be deposited
and locally melted. The deposition and fusing of the powder can be
repeated as needed to construct the part, layer by layer.
[0127] For example, a first layer of powder formed of the Al alloy
can spread out over a mold base. A laser beam can heat up the power
above the melting point. The powder heated by the laser is fused
together. The fused powder is cooled down. A second layer of fresh
powder can spread over the first layer of alloy. The second layer
of powder is heated up by the laser beam above the melting point
such that the powder is fused together. The second fused layer of
powder is cooled down for form a layer of alloy over the first
layer of alloy. This process continues with another layer of
powder. Each of the additional layers of powder is built up over
the previous alloy layer, not over the mold base.
[0128] V. Non-Iron Mold (i.e. Non-Die) Casting
[0129] The alloys can produce a cosmetically appealing anodized
finish, and/or to have a yield strength of at least 200 MPa. These
alloys may be used to fabricate electronic housings by non-metal
mold casting, such as sand casting or investment casting. The sand
casting uses sand as the mold material. Over 70% of all metal
castings are produced via sand casting process.
[0130] Investment casting uses waxes, refractory materials (e.g.
ceramic materials and glasses) for making molds. Investment casting
is valued for its ability to produce components with accuracy,
repeatability, versatility and integrity in a variety of metals and
high-performance alloys.
[0131] During casting, an alloy melt is poured into a mold cavity
that is an exact duplicate of the desired part. The investment
casting can produce complicated shapes that would be difficult with
other casting methods. It can also produce products with
exceptional surface qualities and low tolerances with minimal
surface finishing or machining required.
[0132] The present alloys are not suitable for iron-based mold.
This is because that the present aluminum alloys contain very small
amount of Fe and are more likely to stick to the iron-based metal
mold by forming alloys including Fe.
[0133] In some embodiments, a melt for an alloy can be prepared by
heating the alloy including the composition, for example, as
depicted in Table 1. After the melt is cooled to room temperature,
the alloys may go through various heat treatments, such
homogenization, extruding, forging, aging, and/or other forming or
solution heat treatment techniques. Homogeneous treatment or
solution treatment dissolves second phase particles or
precipitates.
[0134] The alloy can fill a mold more completely during casting
with reduced risk of hot tearing. In various embodiments, the
alloys can have a small solidification temperature range, which can
result in improved additive manufacturability of the alloys. As an
example, the commercial alloy 6063 has a large solidification
temperature range and a small eutectic fraction, which is not
suitable for casting.
[0135] FIG. 7A depicts an example mold cavity in accordance with
embodiments of the disclosure. The mold cavity 702 has an H-shape
with two vertical arms and a thin horizontal portion to connect the
two arms. As shown by the arrow, molten aluminum 704 can be
injected into a thin middle portion from a filling channel 716 and
can be forced to flow into the mold cavity 702.
[0136] FIG. 7B depicts an example of partial mold filling following
FIG. 7A in accordance with embodiments of the disclosure. Molten
aluminum 704 completely fills the horizontal middle portion and
partially fills the vertical arms of the mold cavity 702.
[0137] FIG. 7C depicts an example of complete mold filling
following FIG. 7B in accordance with embodiments of the disclosure.
As depicted, molten aluminum 708 completely fills the vertical arms
and the horizontal middle portion of mold cavity 702.
[0138] FIG. 7D depicts an example of partial solidification
following FIG. 7C in accordance with embodiments of the disclosure.
The molten aluminum in the two vertical arms of the cavity 702 has
solidified (portion 710), while the molten aluminum still remains
partially unsolidified in the horizontal middle portion (portion
712).
[0139] FIG. 7E depicts an example of complete solidification
following FIG. 7D in accordance with embodiments of the disclosure.
As depicted, there is a remaining small amount of liquid in the
filling channel 716. The alloy in the thinner horizontal portion of
the mold cavity experiences a tensile stress as arrows pointed. The
tensile stress is induced by the alloy contraction in the two
vertical arms during a phase transition from liquid to solid.
[0140] FIG. 7F depicts an example of the alloy in the mold cavity
without any hot tearing following FIG. 7E in accordance with
embodiments of the disclosure. The alloy has a large eutectic
fraction 102 as shown in FIG. 1, which can result in less
contraction and thus a lower tensile stress.
[0141] FIG. 7G depicts an example of the alloy in the mold cavity
with hot tearing in the middle of the thin portion following FIG.
7E in accordance with embodiments of the disclosure. The commercial
alloy (e.g. 6063-T6) has a small eutectic fraction 104 as shown in
FIG. 1, which may result in a larger contraction and thus a higher
tensile stress.
[0142] Castability of the alloys may be quantitatively evaluated.
For example, by using the H-shape mold cavity, shown in FIG. 7A,
the middle portion may vary in thickness.
[0143] Quantitative evaluations of castability are described below.
FIGS. 8A-8B depict an example mold cavity middle portion 802 with
varying thicknesses: thinner mold cavity (FIG. 8A) and thicker mold
cavity (FIG. 8B). An alloy may be characterized by filling the mold
cavity. In some embodiments, when the alloy can fill the thinner
mold cavity, the alloy may have a better fluidity or castability
than the alloy can only fill a thicker mold cavity. In some
embodiments, the alloy may fill the mold cavity partially, and the
filled distance can be measured to quantify the fluidity of the
alloy.
[0144] In various embodiments, the alloy may be casted at a casting
temperature ranging from 50.degree. C. to 100.degree. C. higher
than the liquidus temperature of the alloy. In some embodiments,
the casting temperature is up to 100.degree. C. higher than the
liquidus temperature of the alloy. In some embodiments, the casting
temperature is up to 90.degree. C. higher than the liquidus
temperature of the alloy. In some embodiments, the casting
temperature is up to 80.degree. C. higher than the liquidus
temperature of the alloy. In some embodiments, the casting
temperature is up to 70.degree. C. higher than the liquidus
temperature of the alloy. In some embodiments, the casting
temperature is up to 60.degree. C. higher than the liquidus
temperature of the alloy. In some embodiments, the casting
temperature is up to 50.degree. C. higher than the liquidus
temperature of the alloy.
[0145] In various embodiments, the liquidus temperature of the
alloy is about 650.degree. C. Accordingly, the casting temperature
ranges from 700.degree. C. to 750.degree. C. In some embodiments,
the casting temperature is up to 750.degree. C. In some
embodiments, the casting temperature is up to 740.degree. C. In
some embodiments, the casting temperature is up to 730.degree. C.
In some embodiments, the casting temperature is up to 720.degree.
C. In some embodiments, the casting temperature is up to
710.degree. C. In some embodiments, the casting temperature is up
to 700.degree. C. In some embodiments, the casting temperature may
be greater than 700.degree. C. In some embodiments, the casting
temperature may be greater than 710.degree. C. In some embodiments,
the casting temperature may be greater than 720.degree. C. In some
embodiments, the casting temperature may be greater than
730.degree. C. In some embodiments, the casting temperature may be
greater than 740.degree. C.
[0146] In various embodiments, a shot sleeve used to deliver an
amount of the melted alloy may be maintained at a temperature
ranging from about 200.degree. C. to about 500.degree. C. In some
embodiments, the shot sleeve may be maintained at a temperature of
at least 200.degree. C. In some embodiments, the shot sleeve may be
maintained at a temperature of at least 250.degree. C. In some
embodiments, the shot sleeve may be maintained at a temperature of
at least 300.degree. C. In some embodiments, the shot sleeve may be
maintained at a temperature of at least 350.degree. C. In some
embodiments, the shot sleeve may be maintained at a temperature of
at least 400.degree. C. In some embodiments, the shot sleeve may be
maintained at a temperature of at least 450.degree. C. In some
embodiments, the shot sleeve may be maintained at a temperature of
less than 500.degree. C. In some embodiments, the shot sleeve may
be maintained at a temperature of less than 450.degree. C. In some
embodiments, the shot sleeve may be maintained at a temperature of
less than 400.degree. C. In some embodiments, the shot sleeve may
be maintained at a temperature of less than 350.degree. C. In some
embodiments, the shot sleeve may be maintained at a temperature of
less than 300.degree. C. In some embodiments, the shot sleeve may
be maintained at a temperature of less than 250.degree. C.
[0147] In various embodiments, the alloy may be casted into a
non-metal mold maintained at a temperature ranging from about
200.degree. C. to about 500.degree. C. In some embodiments, the
non-metal mold may be maintained at a temperature of at least
200.degree. C. In some embodiments, the non-metal mold may be
maintained at a temperature of at least 250.degree. C. In some
embodiments, the non-metal mold may be maintained at a temperature
of at least 300.degree. C. In some embodiments, the non-metal mold
may be maintained at a temperature of at least 350.degree. C. In
some embodiments, the non-metal mold may be maintained at a
temperature of at least 400.degree. C. In some embodiments, the
non-metal mold may be maintained at a temperature of at least
450.degree. C. In some embodiments, the non-metal mold may be
maintained at a temperature of less than 500.degree. C. In some
embodiments, the non-metal mold may be maintained at a temperature
of less than 450.degree. C. In some embodiments, the non-metal mold
may be maintained at a temperature of less than 400.degree. C. In
some embodiments, the non-metal mold may be maintained at a
temperature of less than 350.degree. C. In some embodiments, the
non-metal mold may be maintained at a temperature of less than
300.degree. C. In some embodiments, the non-metal mold may be
maintained at a temperature of less than 250.degree. C.
[0148] In various embodiments, the solidification temperature
ranges is smaller than 60.degree. C. In some embodiments, the
solidification temperature ranges is smaller than 55.degree. C. In
some embodiments, the solidification temperature ranges is smaller
than 50.degree. C. In some embodiments, the solidification
temperature ranges is smaller than 45.degree. C. In some
embodiments, the solidification temperature ranges is smaller than
40.degree. C. In some embodiments, the solidification temperature
ranges is smaller than 35.degree. C. In some embodiments, the
solidification temperature ranges is smaller than 30.degree. C. In
some embodiments, the solidification temperature ranges is smaller
than 25.degree. C. In some embodiments, the solidification
temperature ranges is smaller than 20.degree. C. In some
embodiments, the solidification temperature ranges is smaller than
15.degree. C. In some embodiments, the solidification temperature
ranges is smaller than 10.degree. C. In some embodiments, the
solidification temperature ranges is smaller than 5.degree. C. It
will be appreciated by those skilled in the art that the
composition space may vary with the solidification temperature
range.
[0149] Having described several embodiments, it will be recognized
by those skilled in the art that various modifications, alternative
constructions, and equivalents may be used without departing from
the spirit of the disclosure. Additionally, a number of well-known
processes and elements have not been described in order to avoid
unnecessarily obscuring the embodiments disclosed herein.
Accordingly, the above description should not be taken as limiting
the scope of the document.
[0150] Those skilled in the art will appreciate that the presently
disclosed embodiments teach by way of example and not by
limitation. Therefore, the matter contained in the above
description or shown in the accompanying drawings should be
interpreted as illustrative and not in a limiting sense. The
following claims are intended to cover all generic and specific
features described herein, as well as all statements of the scope
of the present method and system, which, as a matter of language,
might be said to fall there between.
* * * * *