U.S. patent application number 12/570747 was filed with the patent office on 2011-03-24 for magnesium mother alloy, manufacturing method thereof, metal alloy using the same, and method of manufacturing metal alloy.
This patent application is currently assigned to Korea Institute of Industrial Technology. Invention is credited to In Kyum Kim, Shea Kwang Kim, Jung Ho Seo.
Application Number | 20110070120 12/570747 |
Document ID | / |
Family ID | 43383404 |
Filed Date | 2011-03-24 |
United States Patent
Application |
20110070120 |
Kind Code |
A1 |
Kim; Shea Kwang ; et
al. |
March 24, 2011 |
MAGNESIUM MOTHER ALLOY, MANUFACTURING METHOD THEREOF, METAL ALLOY
USING THE SAME, AND METHOD OF MANUFACTURING METAL ALLOY
Abstract
Disclosed are a magnesium mother alloy, a manufacturing method
thereof, a metal alloy using the same, and a method of
manufacturing the metal alloy. In particular, there are provided a
magnesium mother alloy with improved oxidation and ignition
properties, and a manufacturing method thereof, and also provided a
metal alloy with low cost that is suitable for design purposes
using the magnesium mother alloy, and a method of manufacturing the
metal alloy. The magnesium mother alloy includes a plurality of
magnesium grains, and scandium dissolved in the magnesium grains,
or a scandium compound crystallized at grain boundaries which are
not inside but outside the magnesium grains. Also, the metal alloy
suitable for design purposes is manufactured at low cost by adding
the magnesium mother alloy containing scandium into a magnesium
alloy or an aluminum alloy.
Inventors: |
Kim; Shea Kwang; (Seoul,
KR) ; Seo; Jung Ho; (Gyeongsangnam-do, KR) ;
Kim; In Kyum; (Chungcheongbuk-do, KR) |
Assignee: |
Korea Institute of Industrial
Technology
|
Family ID: |
43383404 |
Appl. No.: |
12/570747 |
Filed: |
September 30, 2009 |
Current U.S.
Class: |
420/407 ;
164/57.1; 420/402 |
Current CPC
Class: |
C22C 23/02 20130101;
C22C 1/03 20130101; C22C 21/00 20130101; C22C 23/00 20130101 |
Class at
Publication: |
420/407 ;
164/57.1; 420/402 |
International
Class: |
C22C 23/02 20060101
C22C023/02; B22D 27/00 20060101 B22D027/00; C22C 23/00 20060101
C22C023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 21, 2009 |
KR |
10-2009-0088959 |
Claims
1. A magnesium mother alloy comprising: a plurality of magnesium
grains; and scandium (Sc) dissolved in the magnesium grains.
2. The magnesium mother alloy of claim 1 wherein the scandium (Sc)
is contained in the magnesium mother alloy ranging from about
0.0001 wt % to about 30 wt % based on 100 wt % of the
magnesium.
3. A magnesium mother alloy comprising: a plurality of
magnesium-aluminum grains having grain boundaries; and a scandium
compound crystallized at the grain boundaries which are not inside
but outside of the magnesium-aluminum grains.
4. The magnesium mother alloy of claim 3 wherein the scandium
compound is selected from the group consisting of Al.sub.2Sc, AlSc
and Al.sub.3Sc.
5. The magnesium mother alloy of claim 3 wherein the scandium (Sc)
is contained in the scandium compound ranging from about 0.0001 wt
% to about 30 wt % based on 100 wt % of the magnesium-aluminum.
6. A method of manufacturing a magnesium mother alloy, the method
comprising: forming a magnesium melt by putting magnesium into a
crucible and melting the magnesium at a temperature ranging from
about 600.degree. C. to about 800.degree. C.; adding scandium oxide
(Sc.sub.2O.sub.3) into the magnesium melt; stirring the magnesium
melt for about 1 minute to about 400 minutes; pouring the magnesium
melt into a mold having a temperature ranging from a room
temperature to about 400.degree. C. and casting the magnesium melt;
and cooling the magnesium melt casting.
7. The method as claimed of claim 6 wherein the magnesium is
selected from the group consisting of pure magnesium and
magnesium-aluminum.
8. The method as claimed of claim 6 wherein the scandium oxide is
added into the magnesium melt ranging from about 0.0001 wt % to
about 30 wt % based on 100 wt % of the magnesium.
9. A metal alloy comprising: a plurality of metal grains having
grain boundaries; and a scandium compound crystallized at the grain
boundaries which are not inside but outside the metal grains.
10. The metal alloy of claim 9 wherein the metal is selected from
the group consisting of AZ91D, AM20, AM30, AM50, AM60, AZ31, AZ61,
AZ80, AS41, AS31, AS21X, AE42, AE44, AX51, AX52, AJ50X, AJ52X,
AJ62X, MRI153, MRI230, AM-HP2, Mg--Al, Mg--Al--Re, Mg--Al--Sn,
Mg--Zn--Sn, Mg--Si, and Mg--Zn--Y.
11. The metal alloy of claim 9 wherein the metal is selected from
the group consisting of 1000-series, 2000-series, 3000-series,
4000-series, 5000-series, 6000-series, 7000-series and 8000-series
wrought aluminum, and 100-series, 200-series, 300-series,
400-series, 500-series, and 700-series casting aluminum.
12. The metal alloy of claim 9 wherein the scandium compound is
selected from the group consisting of Al.sub.2Sc, AlSc and
Al.sub.3Sc.
13. The metal alloy of claim 9 wherein the scandium (Sc) is
contained in the scandium compound ranging from about 0.0001 wt %
to about 30 wt % based on 100 wt % of the metal.
14. A method of manufacturing a metal alloy, the method comprising:
forming a metal melt; adding a magnesium mother alloy containing
scandium (Sc) into the metal melt; stirring the metal melt for
about 1 minute to about 400 minutes; pouring the metal melt into a
mold having a temperature ranging from a room temperature to about
400.degree. C. and casting the metal melt; and cooling the metal
casting.
15. The method of claim 14 wherein the magnesium mother alloy
containing scandium (Sc) is added into the metal melt ranging from
about 0.0001 wt % to about 30 wt % based on 100 wt % of the
metal.
16. The method of claim 14 wherein the magnesium mother alloy
containing scandium (Sc) is manufactured by adding about 0.0001 wt
% to about 30 wt % of scandium oxide (Sc.sub.2O.sub.3) based on 100
wt % of pure magnesium.
17. The method of claim 14 wherein the magnesium mother alloy
containing scandium (Sc) is manufactured by adding about 0.0001 wt
% to about 30 wt % of scandium oxide (Sc.sub.2O.sub.3) based on 100
wt % of magnesium-aluminum.
18. The method of claim 14 wherein the magnesium mother alloy
containing scandium (Sc) is selected from the group consisting of
an alloy prepared by adding about 0.0001 wt % to about 30 wt % of
scandium oxide (Sc.sub.2O.sub.3) based on 100 wt % of pure
magnesium, and an alloy prepared by adding about 0.0001 wt % to
about 30 wt % of scandium oxide (Sc.sub.2O.sub.3) based on 100 wt %
of magnesium-aluminum.
19. The method of claim 14 wherein the metal melt is formed of one
selected from the group consisting of AZ91D, AM20, AM30, AM50,
AM60, AZ31, AZ61, AZ80, AS41, AS31, AS21X, AE42, AE44, AX51, AX52,
AJ50X, AJ52X, AJ62X, MRI153, MRI230, AM-HP2, Mg--Al, Mg--Al--Re,
Mg--Al--Sn, Mg--Zn--Sn, Mg--Si, and Mg--Zn--Y.
20. The method of claim 14 wherein the metal melt is formed of one
selected from the group consisting of 1000-series, 2000-series,
3000-series, 4000-series, 5000-series, 6000-series, 7000-series and
8000-series wrought aluminum, and 100-series, 200-series,
300-series, 400-series, 500-series, and 700-series casting
aluminum.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of
Korean Patent Application No. 10-2009-0088959, filed on Sep. 21,
2009, which is herein incorporated by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to a magnesium
mother alloy, a manufacturing method thereof, a metal alloy using
the same, and a method of manufacturing the metal alloy. More
particularly, the present invention relates to a magnesium mother
alloy with improved oxidation and ignition properties, and a
manufacturing method thereof, and also relates to a metal alloy
with low cost that is suitable for design purposes using the
magnesium mother alloy, and a method of manufacturing the metal
alloy.
[0004] 2. Description of the Related Art
[0005] Currently, using scandium (Sc) as an additive in super-hard
aluminum alloys (for example, 2000-series, 5000-series,
6000-series, 7000-series aluminum alloys, etc.) have been
researched and developed so as to improve alloy properties such as
hardness, corrosion resistance and weldability. Aluminum alloys
with scandium (Sc) added may be used for military purposes (for
example, reinforcement for combat vehicles, rifle bodies, etc.)
requiring good weldability and fatigue resistance, or may be used
for private purposes (for example, a high-speed train, parts for an
electric train, etc.).
[0006] However, scandium (Sc) is a rare earth material, and the
amount of scandium (Sc) existing on the earth is too small.
Furthermore, there is a difficulty in separating scandium (Sc) from
a mineral, and thus scandium (Sc) is very expensive. Therefore, a
method of adding scandium oxide (Sc.sub.2O.sub.3) into aluminum
alloys is now being considered because scandium oxide
(Sc.sub.2O.sub.3) is relatively cheaper than scandium (Sc)
itself.
[0007] Unfortunately, when Sc.sub.2O.sub.3 is directly added into
aluminum alloys, various alloy properties such as hardness,
corrosion resistance and weldability are deteriorated due to oxides
of scandium (Sc).
SUMMARY OF THE INVENTION
[0008] Embodiments are directed to a magnesium mother alloy, a
manufacturing method thereof, a metal alloy using the same, and a
method of manufacturing the metal alloy, which substantially
overcome one or more of the problems due to the limitations and
disadvantages of the related art.
[0009] It is therefore a feature of an embodiment to provide a
magnesium mother alloy with improved oxidation and ignition
properties, and a manufacturing method thereof.
[0010] It is therefore a feature of another embodiment to provide a
metal alloy with low cost, which is adapted for design purposes and
does not deteriorate alloy properties such as hardness, corrosion
resistance and weldability, and a manufacturing method thereof.
[0011] At least one of the above and other features and advantages
may be realized by providing a magnesium mother alloy including: a
plurality of magnesium grains; and scandium (Sc) dissolved in the
magnesium grains.
[0012] The scandium may exist in an amount of about 0.0001 wt % to
about 30 wt % based on 100 wt % of the magnesium.
[0013] At least one of the above and other features and advantages
may be realized by providing a magnesium mother alloy including: a
plurality of magnesium-aluminum grains having grain boundaries; and
a scandium compound crystallized at the grain boundaries which are
not inside but outside of the magnesium-aluminum grains.
[0014] The scandium compound may include Al.sub.2Sc, AlSc and
Al.sub.3Sc.
[0015] The scandium of the scandium compound may exist in an amount
of about 0.0001 wt % to about 30 wt % based on 100 wt % of the
magnesium-aluminum
[0016] At least one of the above and other features and advantages
may be realized by providing a method of manufacturing a magnesium
mother alloy including: forming a magnesium melt by putting
magnesium into a crucible and melting the magnesium at a
temperature ranging from about 600.degree. C. to about 800.degree.
C.; adding scandium oxide (Sc.sub.2O.sub.3) into the magnesium
melt; stirring the magnesium melt for about 1 minute to about 400
minutes; pouring the magnesium melt into a mold having a
temperature ranging from a room temperature to about 400.degree. C.
and casting the magnesium melt; and cooling the cast magnesium melt
casting.
[0017] In the forming of the magnesium melt, the magnesium may be
pure magnesium or magnesium-aluminum.
[0018] An added amount of the scandium oxide may be about 0.0001 wt
% to about 30 wt % based on 100 wt % of pure magnesium or
magnesium-aluminum
[0019] At least one of the above and other features and advantages
may be realized by providing a metal alloy including: a plurality
of metal grains having grain boundaries; and scandium dissolved in
the metal grains, or a scandium compound crystallized at the grain
boundaries which are not inside but outside the metal grains.
[0020] The metal may include one selected from consisting of AZ91D,
AM20, AM30, AM50, AM60, AZ31, AZ61, AZ80, AS41, AS31, AS21X, AE42,
AE44, AX51, AX52, AJ50X, AJ52X, AJ62X, MRI153, MRI230, AM-HP2,
Mg--Al, Mg--Al--Re, Mg--Al--Sn, Mg--Zn--Sn, Mg--Si, and
Mg--Zn--Y.
[0021] The metal may include one selected from consisting of
1000-series, 2000-series, 3000-series, 4000-series, 5000-series,
6000-series, 7000-series and 8000-series wrought aluminum, and
100-series, 200-series, 300-series, 400-series, 500-series, and
700-series casting aluminum.
[0022] The scandium compound may include Al.sub.2Sc, AlSc and
Al.sub.3Sc.
[0023] The scandium dissolved in the metal grains or the scandium
of the scandium compound may exist in an amount of about 0.0001 wt
% to about 30 wt % based on 100 wt % of the metal.
[0024] At least one of the above and other features and advantages
may be realized by providing a method of manufacturing a metal
alloy including: forming a metal melt; adding a magnesium mother
alloy containing dissolved scandium or scandium oxide
(Sc.sub.2O.sub.3) into the metal melt; stirring the metal melt for
about 1 to about 400 minutes; pouring the metal melt into a mold
having a temperature ranging from a room temperature to about
400.degree. C. and casting the metal melt; and cooling the metal
casting.
[0025] An added amount of the magnesium mother alloy containing
scandium may be about 0.0001 wt$ to about 30 wt % based on 100 wt %
of the metal.
[0026] The magnesium mother alloy containing scandium may be
manufactured by adding about 0.0001 wt % to about 30 wt % of
scandium oxide (Sc.sub.2O.sub.3) based on 100 wt % of pure
magnesium.
[0027] The magnesium mother alloy containing scandium may be
manufactured by adding about 0.0001 wt % to about 30 wt % of
scandium oxide (Sc.sub.2O.sub.3) based on 100 wt % of
magnesium-aluminum.
[0028] The magnesium mother alloy containing scandium may include
an alloy prepared by adding about 0.0001 wt % to about 30 wt % of
scandium oxide (Sc.sub.2O.sub.3) based on 100 wt % of pure
magnesium, and an alloy prepared by adding about 0.0001 wt % to
about 30 wt % of scandium oxide (Sc.sub.2O.sub.3) based on 100 wt %
of magnesium-aluminum.
[0029] The metal melt may be formed of one selected from consisting
of AZ91D, AM20, AM30, AM50, AM60, AZ31, AZ61, AZ80, AS41, AS31,
AS21X, AE42, AE44, AX51, AX52, AJ50X, AJ52X, AJ62X, MRI153, MRI230,
AM-HP2, Mg--Al, Mg--Al--Re, Mg--Al--Sn, Mg--Zn--Sn, Mg--Si, and
Mg--Zn--Y.
[0030] The metal melt may be formed of one selected from consisting
of 1000-series, 2000-series, 3000-series, 4000-series, 5000-series,
6000-series, 7000-series and 8000-series wrought aluminum, and
100-series, 200-series, 300-series, 400-series, 500-series, and
700-series casting aluminum.
[0031] These and other features of the present invention will be
more readily apparent from the detailed description set forth below
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The above and other features and advantages will become more
apparent to those of ordinary skill in the art by describing in
detail exemplary embodiments with reference to the attached
drawings, in which:
[0033] FIG. 1 is a flowchart illustrating a method of manufacturing
a magnesium mother alloy according to an embodiment;
[0034] FIG. 2 is a micrograph illustrating a microstructure of a
magnesium mother alloy in which scandium oxide is added into pure
magnesium and scandium (Sc) exists in a solid-solution state;
[0035] FIG. 3 is a micrograph illustrating a microstructure of a
magnesium mother alloy in which scandium oxide is added to
magnesium-aluminum and a scandium compound is crystallized;
[0036] FIG. 4 is a graph illustrating hardness comparison results
between a pure magnesium and a magnesium mother alloy with scandium
oxide added according to an embodiment;
[0037] FIG. 5 is a graph illustrating oxidation experimental
results between a pure magnesium and a magnesium mother alloy with
scandium oxide added according to an embodiment;
[0038] FIG. 6 is a graph illustrating ignition experimental results
between a pure magnesium and a magnesium mother alloy with scandium
oxide added according to an embodiment;
[0039] FIG. 7 is a graph illustrating hardness comparison results
between a magnesium-aluminum alloy and a magnesium-aluminum alloy
with scandium oxide added according to an embodiment; and
[0040] FIG. 8 is a flowchart illustrating a method of manufacturing
a metal alloy according to an embodiment.
[0041] In the following description, the same or similar elements
are labeled with the same or similar reference numbers.
DETAILED DESCRIPTION
[0042] The present invention now will be described more fully
hereinafter with reference to the accompanying drawings, in which
embodiments of the invention are shown. This invention may,
however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein. Rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art.
[0043] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
[0044] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
[0045] Preferred embodiments of the present invention will now be
described in detail with reference to the accompanying
drawings.
[0046] FIG. 1 is a flowchart illustrating a method of manufacturing
a magnesium mother alloy according to an embodiment.
[0047] The method of manufacturing the magnesium mother alloy
includes forming a magnesium melt operation S1, adding an additive
operation S2, stirring operation S3, casting operation S4, and
cooling operation S5.
[0048] In the forming a magnesium melt operation S1, magnesium is
put into a crucible and heated at a temperature ranging from about
600.degree. C. to about 800.degree. C. Then, the magnesium in the
crucible is molten to form a magnesium melt. If the temperature is
lower than about 600.degree. C., it is difficult for forming the
magnesium melt. If the temperature is higher than about 800.degree.
C., ignition may easily occur in the magnesium melt.
[0049] Additionally, a small amount of a shield gas may be provided
to prevent the ignition of the magnesium melt. The shield gas may
inhibit the ignition of the magnesium using SF.sub.6, SO.sub.2,
CO.sub.2, HFC-134a, Novec.TM.612, inert gas or an equivalent
thereof, or a mixture gas thereof. It should be noted that the
listing of the above materials should not be seen as to limit the
scope of the present invention. Other materials may be used without
departing from the spirit and scope of the present invention.
[0050] The magnesium used in operation S1 of forming the magnesium
melt may be one selected from consisting of pure magnesium,
magnesium-aluminum, and equivalents thereof. However, other types
of material may be used without departing from the spirit and scope
of the present invention.
[0051] In the adding an additive operation S2, a powdered additive
is added to the magnesium melt. The additive used in operation S2
of adding the additive may not be pure scandium (Sc) of high price,
but may be one selected from consisting of scandium oxide
(Sc.sub.2O.sub.3) which is relatively cheap, and equivalents
thereof. The additive reduces the oxidation of a magnesium mother
alloy, raises the ignition temperature, and remarkably reduces the
required amount of the shield gas.
[0052] The additive used in operation S2 may be added in an amount
of about 0.0001 wt % to about 30 wt % based on 100 wt % of the
magnesium mother alloy. When the amount of the additive is less
than 0.0001 wt %, the effect (increase in hardness, decrease in
oxidation, increase in ignition temperature and decrease in shield
gas) resulting from the addition of the additive may be little.
When the amount of the additive exceeds 30 wt %, original magnesium
properties or magnesium alloy properties may not appear.
[0053] The additive used in operation S2 may have a size ranging
from about 0.1 .mu.m to about 500 .mu.m. If the additive is smaller
than 0.1 .mu.m, it is difficult to manufacture the additive and it
requires high manufacturing cost. When the size of the additive
exceeds about 500 .mu.m, the additive may not react with the
magnesium melt.
[0054] In the stirring operation S3, the magnesium melt is stirred
for about 1 minute to about 400 minutes. If the stirring time is
less than 1 minute, the additive is not sufficiently mixed with the
magnesium melt. If the stirring time is greater than 400 minutes,
the stirring time of the magnesium melt is unnecessarily
lengthened.
[0055] The additive added into the magnesium melt does not exist in
an oxide form. For example, when scandium oxide (Sc.sub.2O.sub.3)
is added into the magnesium melt, it does not exist in the form of
Sc.sub.2O.sub.3. That is, Sc.sub.2O.sub.3, after being reduced,
reacts with elements in the magnesium melt so that scandium (Sc) is
dissolved in grains to exist in an alloy form, or crystallized to
exist in a compound form.
[0056] It is generally expected that Sc.sub.2O.sub.3 is not reduced
in the magnesium melt because Sc.sub.2O.sub.3 is thermodynamically
more stable than magnesium. However, according to experiments
conducted by the present inventors, it was found out that
Sc.sub.2O.sub.3 is reduced in the magnesium melt. This reduction
mechanism is not discovered yet, and therefore the present
inventors continue to study in order to diagnose the reduction
mechanism.
[0057] When Sc.sub.2O.sub.3 is added into pure magnesium, scandium
(Sc) is dissolved in the pure magnesium. That is, scandium (Sc)
forms an alloy element with magnesium. When Sc.sub.2O.sub.3 is
added into magnesium-aluminum, a scandium (Sc) compound is
crystallized at a grain boundary of the magnesium-aluminum. That
is, scandium (Sc) does not form an alloy element with magnesium but
forms the Sc compound. Here, the scandium (Sc) compound is in the
form of Al.sub.2Sc, AlSc or Al.sub.3Sc typically.
[0058] The other element, oxygen (O.sub.2), of the additive all
float on the surface of the magnesium melt, and thus can be removed
manually or using an automatic equipment.
[0059] In the casting operation S4, the magnesium melt is poured
into a mold having a room temperature (e.g., about 25.degree. C.)
to about 400.degree. C., and then casted.
[0060] The mold may be one selected from group consisting of a
metal type, a ceramic type, a graphite type and equivalents
thereof. Also, a casting may be performed using gravity casting
method, continuous casting method and equivalents thereof. It
should be noted that other types of mold may be used without
departing from the spirit and scope of the present invention.
Further, it should be noted that the casting method is not limited
to the above mentioned methods without departing from the spirit
and scope of the present invention.
[0061] In the cooling operation S5, the mold is cooled down to a
room temperature, and magnesium or magnesium-aluminum (e.g., ingot)
is picked out of the mold.
[0062] The magnesium mother alloy prepared through the
above-described method may include a plurality of magnesium grains
having grain boundaries therebetween, and scandium (Sc) dissolved
in the magnesium grains, or may include a scandium compound
existing at the grain boundaries which are not inside but outside
the magnesium grains.
[0063] FIG. 2 is a micrograph illustrating a microstructure of a
magnesium mother alloy in which scandium oxide is added into pure
magnesium and Sc exists in a solid-solution state. The
microstructure shown in FIG. 2 is obtained by, for example, adding
0.5% scandium oxide into pure magnesium.
[0064] As shown in FIG. 2, a magnesium mother alloy 100 prepared
according to an embodiment includes a plurality of magnesium grains
110, and scandium (Sc) dissolved in the magnesium grains 110. Here,
the scandium is not discriminated from the magnesium grains 110
substantially because scandium (Sc) forms an alloy with
magnesium.
[0065] The hardness of the magnesium mother alloy manufactured by
adding scandium oxide is improved compared to that of pure
magnesium. Since the scandium (Sc) does not change the original
composition of the magnesium mother alloy and does not disappear
during a process of recycling the magnesium mother alloy, the
reusability of magnesium mother alloy is considerably enhanced.
That is, it is unnecessary to add scandium (Sc) or scandium oxide
again during the recycle of magnesium mother alloy.
[0066] In this embodiment, about 0.0001 wt % to about 30 wt % of
scandium oxide may be added based on 100 wt % of magnesium. The
scandium oxide may have a size ranging from about 0.1 .mu.m to
about 500 .mu.m. The meaning of such a numerical range has already
been described above.
[0067] FIG. 3 is a micrograph illustrating a microstructure of a
magnesium mother alloy in which scandium oxide is added to
magnesium-aluminum and a scandium compound is crystallized. For
example, the microstructure in FIG. 3 is obtained by adding 0.5 wt
% scandium oxide into magnesium-aluminum (Mg-3Al).
[0068] As shown in FIG. 3, a magnesium mother alloy 200 according
to an embodiment includes a plurality of magnesium-aluminum grains
210, and a scandium compound 211.
[0069] The magnesium-aluminum grains 210 have grain boundaries
therebetween, and the scandium compound 211 exists at the grain
boundaries which are not inside the grains 210 but outside the
magnesium-aluminum grains 210. Here, the scandium compound 211
exists in the form of Al.sub.2Sc, AlSc or Al.sub.3Sc. That is, the
scandium does not form an alloy with magnesium. Accordingly the
hardness of the magnesium mother alloy 200 is enhanced, which will
be described below.
[0070] Since the scandium (Sc) does not change the original
composition of the magnesium mother alloy and does not disappear
during a process of recycling the magnesium mother alloy, the
reusability of magnesium mother alloy is considerably enhanced. For
example, it is unnecessary to add scandium or scandium oxide again
during the recycle of magnesium mother alloy.
[0071] Also, about 0.0001 wt % to about 30 wt % of the scandium
compound 211 may be added based on 100 wt % of magnesium-aluminum.
The scandium compound 211 may have a size ranging from about 0.1
.mu.m to about 500 .mu.m. The meaning of such a numerical range has
been already described above.
[0072] The magnesium mother alloy may be used as one selected from
consisting of an incombustible alloy, a wrought alloy, a creep
alloy, a damping alloy, a degradable bio ally, and a powder
metallurgy. It should be noted that the listing of the above
materials should not be seen as to limit the scope of the present
invention. Other materials may be used without departing from the
spirit and scope of the present invention.
[0073] For example, the casting alloy may be formed by mixing
AZ91D, AM20, AM50, or AM60 with scandium oxide.
[0074] The wrought alloy may be formed by mixing AZ31, AM30, AZ61,
or AZ80 with scandium oxide.
[0075] The creep alloy may be formed by mixing Mg--Al, or
Mg--Al--Re with scandium oxide. Furthermore, the creep alloy may be
formed by mixing Mg--Al--Sn or Mg--Zn--Sn with scandium oxide.
[0076] The damping alloy may be formed by mixing Mg, Mg--Si, or
SiCp/Mg with scandium oxide.
[0077] The degradable bio alloy may be formed by mixing pure Mg
with scandium oxide.
[0078] The powder metallurgy may be formed by mixing Mg--Zn--(Y)
with scandium oxide.
[0079] Of course, in all the alloys, only scandium (Sc), which is
obtained by removing O.sub.2 from scandium oxide, is crystallized
and present at grain boundaries, or the scandium exists in the
grains in a solid-solution state finally.
[0080] FIG. 4 is a graph illustrating hardness comparison results
between a pure magnesium and a magnesium mother alloy with scandium
oxide added according to an embodiment. In FIG. 4, the X-axis
represents pure magnesium and magnesium into which 0.5 wt %
scandium oxide is added, and the Y-axis represents hardness
(HR).
[0081] Referring to FIG. 4, it can be observed that the hardness
increases when scandium oxide is added during the manufacture of a
magnesium mother alloy. That is, the hardness of the pure magnesium
without scandium oxide is about HRF41, whereas the hardness of the
magnesium mother alloy with scandium oxide added increases up to
about HRF53.
[0082] FIG. 5 is a graph illustrating oxidation experimental
results between pure magnesium and magnesium mother alloy with
scandium oxide added according to an embodiment. In FIG. 5, the
X-axis represents an elapse time (min.), and the Y-axis represents
oxidation amount (%). A reference value of the Y-axis is set to
100.
[0083] Referring to FIG. 5, in the pure magnesium, it can be
observed that the oxidation of the pure magnesium is accelerated
with the lapse of time, and thus the value of the Y-axis increases
gradually. However, in the magnesium mother alloy into which
scandium oxide is added during manufacturing process, it can be
observed that the oxidation does not increase even after the lapse
of time. That is, the magnesium mother alloy according to an
embodiment is stable for various applications because it is not
oxidized even after the lapse of time.
[0084] FIG. 6 is a graph illustrating ignition experimental results
between pure magnesium and magnesium mother alloy with scandium
oxide added according to an embodiment. In FIG. 6, the X-axis
represents pure magnesium and magnesium into which 0.5 wt %
scandium oxide is added, and the Y-axis represents an ignition
temperature (C).
[0085] Referring to FIG. 6, it can be observed that the ignition
temperature of the magnesium mother alloy with scandium oxide added
is increased. That is, the ignition temperature of the pure
magnesium without scandium oxide is about 600.degree. C., whereas
the ignition temperature of the magnesium mother alloy with
scandium oxide added increases up to about 700.degree. C.
[0086] FIG. 7 is a graph illustrating hardness comparison results
between a magnesium-aluminum alloy and a magnesium-aluminum alloy
with scandium oxide added according to an example embodiment. In
FIG. 7, the X-axis represents a magnesium-aluminum alloy and a
magnesium-aluminum alloy into which 0.5% scandium oxide is added,
and the Y-axis represents hardness (HR).
[0087] Referring to FIG. 7, it can be observed that the hardness
increases when scandium oxide is added during the manufacture of a
magnesium-aluminum alloy. That is, the hardness of the
magnesium-aluminum alloy without scandium oxide is about HRF50,
whereas the hardness of the magnesium-aluminum alloy with scandium
oxide added increases up to HRF68.
[0088] FIG. 8 is a flowchart illustrating a method of manufacturing
a metal alloy according to an embodiment.
[0089] The method of manufacturing the metal alloy includes forming
a metal melt operation S11, adding a magnesium mother alloy
containing scandium (Sc) operation S12, stirring operation S13,
casting operation S14, and cooling operation S15.
[0090] In the forming a metal melt operation S11, a magnesium alloy
or an aluminum alloy is put into a crucible and heated at a
temperature ranging from about 600.degree. C. to about 800.degree.
C. Then, the metal in the crucible is molten to form a metal melt.
There is a difficulty in forming the metal melt when the
temperature is less than 600.degree. C., whereas there is a danger
that the metal melt is ignited when the temperature exceeds
800.degree. C.
[0091] Here, the metal may be a magnesium alloy selected from
consisting of AZ91D, AM20, AM30, AM50, AM60, AZ31, AZ61, AZ80,
AS41, AS31, AS21X, AE42, AE44, AX51, AX52, AJ50X, AJ52X, AJ62X,
MRI153, MRI230, AM-HP2, Mg--Al, Mg--Al--Re, Mg--Al--Sn, Mg--Zn--Sn,
Mg--Si, and Mg--Zn--Y. It should be noted that the listing of the
above materials should not be seen as to limit the scope of the
present invention. Other materials may be used without departing
from the spirit and scope of the present invention.
[0092] Also, the metal may be a metal alloy selected from
consisting of 1000-series, 2000-series, 3000-series, 4000-series,
5000-series, 6000-series, 7000-series and 8000-series wrought
aluminum, and 100-series, 200-series, 300-series, 400-series,
500-series, and 700-series casting aluminum. However, the present
invention is not limited to such materials.
[0093] The aluminum alloys will be described in detail below.
Various types of aluminum alloys have been developed for their use,
and most of countries currently classify the kinds of aluminum
alloys according to the standard stipulated by the Aluminum
Association of America. Main alloy elements for each of alloy
series are listed in Table 1 below in which a serial number is only
shown in units of thousand. In case of improving each of the alloy
series by adding other elements, an alloy name is designated by
subdividing four digits number more specifically.
TABLE-US-00001 TABLE 1 Classification of aluminum according to
alloy series Alloy Series Main alloy elements 1000-series Al Pure
Al 2000-series Al Al--Cu--(Mg)-based Al alloy 3000-series Al
Al--Mn-based Al alloy 4000-series Al Al--Si-based Al alloy
5000-series Al Al--Mg-based Al alloy 6000-series Al
Al--Mg--Si-based Al alloy 7000-series Al Al--Zn--Mg--(Cu)-based Al
alloy 8000-series Al Others
[0094] The first number denotes an alloy series representing main
alloy elements, and the second number denotes whether a basic alloy
is improved or not. That is, the second number of 0 represents a
basic alloy, and the second number of 1 to 9 represents alloys
improved from the basic alloy. Further, when a new alloy is
developed, the second number is indicated by a capital letter N.
For example, 2xxx represents a basic alloy of Al--Cu series
aluminum, 21xx.about.29xx represents alloys obtained by improving
an Al--Cu basic alloy, and 2Nxx represents a newly developed alloy
which is not stipulated in the standard of the Aluminum Association
of America. The third and fourth numbers represent the purity of a
pure aluminum or an alloy name of an aluminum alloy that Alcoa Inc.
has used in the past. For example, in case of pure aluminum, 1080
indicates that the content of aluminum is 99.80% or higher, and
1100 indicates that the content of aluminum is 99.00% or
higher.
[0095] Main compositions of wrought alloys are listed in Table 2
below. Properties of each alloy may significantly differ according
to composition metals and their amounts, and working process. The
main composition of the aluminum alloy is listed in Table 2
below.
TABLE-US-00002 Added metal(element symbol), Unit: % Grade Si Cu Mn
Mg Cr Zn Others Use 1100 0.12 Si 1%, Abundant Fe Metal foils,
cooking utensils 1350 About 0.5% others Conductive material 2008
0.7 0.9 0.4 Metal plates for vehicles 2014 0.8 4.4 0.8 0.5 Exterior
of aircraft, truck frame 2024 4.4 0.6 1.5 Exterior of aircraft,
truck wheel 2036 2.6 0.25 0.45 Metal plates for vehicles 2090 2.7
Li 2.2, Zr 0.12 Metal for aircraft 2091 2.2 1.5 Li 2.0, Zr 0.12
Metal for aircraft 2219 6.3 0.3 V 0.1, Zr 0.18, Ti 0.06 Metal for
spacecraft, weldable 2519 5.9 0.3 0.2 V 0.1, Zr 0.18 Military
equipment, metal for spacecraft, weldable 3003 0.12 1.1 General
use, cooking utensils 3004 1.1 1.0 General use, metal can 3105 0.6
0.5 Building materials 5052 2.5 0.25 General use 5083 0.7 4.4 0.15
Heat-/Pressure-resistant vessels 5182 0.35 4.5 Metal can, metal for
vehicles 5252 2.5 For vehicle bodies 6009 0.8 0.33 0.33 0.5 Metal
plates for vehicles 6010 1.0 0.33 0.33 0.8 Metal plates for
vehicles 6013 0.8 0.8 0.5 1.0 Metal for spacecraft 6061 0.6 0.25
1.0 0.20 General use 6063 0.4 0.7 General use, injection molding
6201 0.7 0.8 Conductive material 7005 0.45 1.4 0.13 4.5 Zr 0.14
Truck body, train 7075 1.6 2.5 0.25 5.6 Metal for aircraft 7150 2.2
2.3 6.4 Zr 0.12 Metal for spacecraft 8090 1.3 0.9 Li 2.4, Zr 0.12
Metal for spacecraft
[0096] In the operation S12 of adding the magnesium mother alloy, a
magnesium mother alloy containing scandium (Sc) is added to the
metal melt. As described above, the metal melt may be a magnesium
alloy or an aluminum alloy.
[0097] The magnesium mother alloy used in the operation S12 may be
manufactured by adding one selected from consisting of scandium
oxide (Sc.sub.2O.sub.3), which is cheaper than pure scandium (Sc),
and equivalents thereof, into magnesium or magnesium-aluminum. The
magnesium and magnesium-aluminum, and methods thereof have been
fully described above, and thus further description will be omitted
herein.
[0098] In this way, according to an exemplary embodiment, magnesium
or magnesium-aluminum alloy containing scandium (Sc) that is
prepared at low cost is added into a metal melt, thus making it
possible to solve several problems occurring when scandium oxide is
directly put into the metal melt. For example, the direct addition
of scandium oxide (Sc.sub.2O.sub.3) into aluminum causes the
quality of an alloy to be deteriorated due to oxides. However, the
quality of an alloy is not deteriorated by adding magnesium or
magnesium-aluminum alloy containing scandium according to the
embodiment. More specifically, alloy properties such as hardness,
corrosion resistance and weldability are deteriorated when scandium
oxide (Sc.sub.2O.sub.3) is directly added into aluminum. However,
alloy properties such as hardness, corrosion resistance and
weldability in the metal alloy according to the embodiment are
maintained without a change when magnesium or magnesium-aluminum
already containing scandium (sc) is added into aluminum.
[0099] For instance, 5000-series metal alloys are strong, easy to
be molded, and highly resistant to corrosion, in comparison with
3000-series metal alloys. Furthermore, 5000-series metal alloys are
weldable. In particular, the 5182 alloy may be used for a cover of
an aluminum can. In addition, 5005 and 5083 alloys, and 5052, 5056,
5086 and varieties thereof may widely be used for electric
facilities, various cooking utensils, metal plate,
pressure-resistant vessels, transmission towers of radio wave,
welding structures, boats, reservoirs for chemicals, etc. Insect
nets, nails, and fasteners may be made of 5000-series alloys. When
magnesium or magnesium-aluminum alloy already containing scandium
is added into such 5000-series metal alloys having the above
properties, it is possible to obtain an aluminum alloy with good
hardness, corrosion resistance and weldability at low cost.
[0100] The additive used in the operation S12 of adding the
magnesium mother alloy may be added in an amount of about 0.0001 wt
% to about 30 wt % based on 100 wt % of the metal. When the amount
of the additive is less than 0.0001 wt %, the effect (hardness,
corrosion resistance, and weldability) resulting from the addition
of magnesium may be little. Also, when the amount of the additive
exceeds 30 wt %, original metal properties may not appear.
[0101] Furthermore, the additive used in the operation S12 of
adding the magnesium mother alloy may have a size ranging from
about 0.1 .mu.m to about 500 .mu.m. It is difficult to manufacture
an additive having a size of 0.1 .mu.m or smaller actually, leading
to high manufacturing cost. When the size of the additive exceeds
500 .mu.m, the magnesium may not react with the metal melt.
[0102] Likewise, the additive used in the operation S12 of adding
the magnesium-aluminum may be added in an amount of about 0.0001 wt
% to about 30 wt % based on 100 wt % of the metal alloy. When the
amount of the additive is less than 0.0001 wt %, the effect
(hardness, corrosion resistance, and weldability) resulting from
the addition of magnesium may be little. Also, when the amount of
the additive exceeds 30 wt %, original metal properties may not
appear.
[0103] Furthermore, the additive used in the operation S12 of
adding the magnesium-aluminum may have a size ranging from about
0.1 .mu.m to about 500 .mu.m. It is difficult to manufacture an
additive having a size of 0.1 .mu.m or smaller actually, leading to
high manufacturing cost. When the size of the additive exceeds 500
.mu.m, the of adding the magnesium-aluminum may not react with the
metal melt.
[0104] In the stirring operation S13, the metal melt is stirred for
about 1 to about 400 minutes. When the stirring time is less than 1
minute, the additive is not sufficiently mixed with the metal melt.
When the stirring time is greater than 400 minutes, the stirring
time of the metal melt is unnecessarily lengthened.
[0105] Here, when the metal melt is aluminum melt, scandium (Sc)
contained in the magnesium added into the aluminum melt exists in
the form of Al.sub.2Sc, AlSc or Al.sub.3Sc due to the high affinity
between scandium (Sc) and aluminum (Al).
[0106] In the stirring operation S13, Al.sub.2Sc, AlSc or
Al.sub.3Sc does not exist in metal grains, but exists outside the
metal grains, i.e., at grain boundaries, in the form of an
intermetallic compound. That is, the metallic compound of
Al.sub.2Sc, AlSc or Al.sub.3Sc is formed in the stirring operation
S13.
[0107] In the casting operation S14, the metal melt is poured into
a mold at a room temperature (e.g., about 25.degree. C.) to about
400.degree. C., and then cast.
[0108] The mold may be one selected from consisting of a metal
type, a ceramic type, a graphite type and equivalents thereof.
Also, a casting may be performed using gravity casting method,
continuous casting method and equivalents thereof. It should be
noted that other types of mold may be used without departing from
the spirit and scope of the present invention. Further, it should
be noted that the casting method is not limited to the above
mentioned methods without departing from the spirit and scope of
the present invention.
[0109] In the cooling operation S15, the mold is cooled down to a
room temperature, and a metal alloy (e.g., metal alloy ingot) is
picked out of the mold.
[0110] The metal alloy manufactured through the above-described
method includes a plurality of metal grains having grain boundaries
therebetween, and an intermetallic compound (i.e., Al.sub.2Sc, AlSc
or Al.sub.3Sc) existing at the grain boundaries which are not
inside but outside the metal grains. Of course, in case where the
metal is pure magnesium, scandium (Sc) is dissolved in the metal
grains.
[0111] As such, according to an exemplary embodiment, a magnesium
mother alloy (Sc-containing magnesium or Sc-containing
magnesium-aluminum) is added into a metal melt (magnesium alloy or
aluminum alloy), thus making it possible to solve several problems
occurring when scandium oxide is directly put into the metal melt.
For example, the direct addition of scandium oxide
(Sc.sub.2O.sub.3) into aluminum causes the quality of an alloy to
be deteriorated due to oxides, however, the addition of
Sc-containing magnesium or scandium (Sc) containing
magnesium-aluminum into aluminum according to an embodiment enables
the aluminum alloy to be manufactured at low cost while not
deteriorating the quality (hardness, corrosion resistance,
weldability, etc.) of an alloy.
[0112] Table 3 below shows experimental data for strength of an
aluminum alloy manufactured through the above-described method.
TABLE-US-00003 TABLE 3 Strength of 7000-series Al alloy Including
Sc 650-700 MPa Not including Sc 550-600 MPa Strength of 5000-series
Al alloy Including Sc 450-500 MPa Not including Sc 350-400 MPa
[0113] As shown in Table 3, it can be understood that the strength
increases up to about 650-700 MPa from about 550-600 MPa when
magnesium or magnesium-aluminum, into which scandium (Sc) has been
already added, is added into 7000-series Al alloy through the
above-described method.
[0114] It can be also understood from Table 3 that the strength
increases up to about 450-500 MPa from about 350-400 MPa when
magnesium or magnesium-aluminum, into which scandium (Sc) has been
already added, is added into 5000-series Al alloy through the
above-described method.
[0115] As such, in a metal alloy and a method thereof according to
the embodiments, a magnesium mother alloy containing scandium (Sc)
is added into a metal alloy such as a magnesium alloy or an
aluminum alloy, and thus the metal alloy is manufactured at low
cost. Furthermore, alloy properties of the metal alloy, e.g.,
hardness, corrosion resistance and weldability, are not
deteriorated.
[0116] In addition, the magnesium mother alloy is manufactured in
such a form that scandium (Sc) is dissolved in metal grains, or
scandium (Sc) is crystallized at grain boundaries, which makes it
possible to easily manufacture a metal alloy suitable for use or
purpose. For example, when a metal alloy where scandium (Sc) is
dissolved is required, a magnesium mother alloy where scandium (Sc)
is dissolved in the metal grains may be used. Also, when a metal
alloy where scandium (Sc) is crystallized is required, a magnesium
mother alloy where scandium (Sc) is crystallized at the grain
boundaries may be used. Of course, a metal alloy may be
manufactured by adding both of the magnesium mother alloy where Sc
is dissolved in metal grains and the magnesium mother alloy where
Sc is crystallized at the grain boundaries.
[0117] As described above, according to foregoing embodiments,
oxidation and ignition properties of a magnesium mother alloy are
enhanced by adding scandium oxide into the magnesium mother alloy.
Also, a metal alloy can be manufactured at low cost because the
magnesium mother alloy containing scandium is added into a metal
alloy such as a magnesium alloy and an aluminum alloy. In this
case, alloy properties, e.g., hardness, corrosion resistance, and
weldability, of the metal alloy are not deteriorated.
[0118] Moreover, it is possible to manufacture a metal alloy
suitable for use and purpose by preparing two types of mother
alloys of which one is a magnesium mother alloy containing scandium
dissolved in grains, and the other is a magnesium mother alloy
where scandium is crystallized. For example, when a metal alloy
where Sc is dissolved is required, a magnesium mother alloy where
Sc is dissolved in the metal grains may be used. Also, when a metal
alloy where Sc is crystallized is required, a magnesium mother
alloy where Sc is crystallized at the grain boundaries may be used.
Of course, a metal alloy may be manufactured by adding both of the
magnesium mother alloy where Sc is dissolved in metal grains and
the magnesium mother alloy where Sc is crystallized at the grain
boundaries. Accordingly, according to the embodiments, it is
possible to manufacture metal alloys suitable for use and purpose
through various methods.
[0119] A magnesium mother alloy, a manufacturing method thereof, a
metal alloy using the same, and a method of manufacturing the metal
alloy according to exemplary embodiments have been disclosed
herein, and although specific terms are employed, they are used and
are to be interpreted in a generic and descriptive sense only and
not for purpose of limitation.
[0120] The drawings and the forgoing description gave examples of
the present invention. The scope of the present invention, however,
is by no means limited by these specific examples. Numerous
variations, whether explicitly given in the specification or not,
such as differences in structure, dimension, and use of material,
are possible. The scope of the invention is at least as broad as
given by the following claims.
* * * * *