U.S. patent application number 14/252585 was filed with the patent office on 2014-11-20 for systems and methods for shaping sheet materials that include metallic glass-based materials.
This patent application is currently assigned to California Institute of Technology. The applicant listed for this patent is California Institute of Technology. Invention is credited to Douglas C. Hofmann, Scott N. Roberts.
Application Number | 20140342179 14/252585 |
Document ID | / |
Family ID | 51896010 |
Filed Date | 2014-11-20 |
United States Patent
Application |
20140342179 |
Kind Code |
A1 |
Hofmann; Douglas C. ; et
al. |
November 20, 2014 |
SYSTEMS AND METHODS FOR SHAPING SHEET MATERIALS THAT INCLUDE
METALLIC GLASS-BASED MATERIALS
Abstract
Systems and methods in accordance with embodiments of the
invention advantageously shape sheet materials that include
metallic glass-based materials. In one embodiment, a method of
shaping a sheet of material including a metallic glass-based
material includes: heating a metallic glass-based material within a
first region within a sheet of material to a temperature greater
than the glass transition temperature of the metallic glass-based
material; where the sheet of material has a thickness of between
0.1 mm and 10 mm; where at least some portion of the sheet of
material does not include metallic glass-based material that is
heated above its respective glass transition temperature when the
metallic glass-based material within the first region is heated
above its respective glass transition temperature; and deforming
the metallic glass-based material within the first region while the
temperature of the metallic glass-based material within the first
region is greater than its respective glass transition
temperature.
Inventors: |
Hofmann; Douglas C.;
(Altadena, CA) ; Roberts; Scott N.; (Altadena,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
California Institute of Technology |
Pasadena |
CA |
US |
|
|
Assignee: |
California Institute of
Technology
Pasadena
CA
|
Family ID: |
51896010 |
Appl. No.: |
14/252585 |
Filed: |
April 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61811405 |
Apr 12, 2013 |
|
|
|
Current U.S.
Class: |
428/613 ;
72/342.1 |
Current CPC
Class: |
Y10T 428/12479 20150115;
C22C 45/10 20130101 |
Class at
Publication: |
428/613 ;
72/342.1 |
International
Class: |
C22C 45/10 20060101
C22C045/10; B21D 37/16 20060101 B21D037/16 |
Goverment Interests
STATEMENT OF FEDERAL FUNDING
[0002] The invention described herein was made in the performance
of work under a NASA contract, and is subject to the provisions of
Public Law 96-517 (35 U.S.C. 202) in which the Contractor has
elected to retain title.
Claims
1. A method of shaping a sheet of material including a metallic
glass-based material comprising: heating a metallic glass-based
material within a first region within a sheet of material to a
temperature greater than the glass transition temperature of the
metallic glass-based material; wherein the sheet of material has a
thickness of between approximately 0.1 mm and approximately 10 mm;
wherein at least some portion of the sheet of material does not
include metallic glass-based material that is heated above its
respective glass transition temperature when the metallic
glass-based material within the first region is heated above its
respective glass transition temperature; and deforming the metallic
glass-based material within the first region while the temperature
of the metallic glass-based material within the first region is
greater than its respective glass transition temperature.
2. The method of claim 1, wherein the sheet of material has a
thickness of between approximately 0.1 mm and approximately 3
mm.
3. The method of claim 2, wherein the temperature of the metallic
glass-based material within the first region is maintained below
its crystallization temperature when it is heated above the glass
transition temperature.
4. The method of claim 3, wherein at least a majority of the sheet
of material, as measured by volume, does not include metallic
glass-based material that is heated above its respective glass
transition temperature when the metallic glass-based material
within the first region is heated above its respective glass
transition temperature.
5. The method of claim 3, wherein heating the metallic glass-based
material within the first region is accomplished using one of:
induction heating, frictional heating, and a heated fluid.
6. The method of claim 3, wherein deforming the metallic
glass-based material within the first region is accomplished by
pressing a shaping tool into the sheet of material.
7. A method of shaping a sheet of material including a metallic
glass-based material comprising: subjecting a sheet of material
comprising a metallic glass-based material to direct contact with a
heated fluid so as to raise the temperature of at least some
portion of the metallic glass-based material to a temperature that
is above its glass transition temperature; wherein the sheet of
material has a thickness of between approximately 0.1 mm and
approximately 10 mm; and deforming the metallic glass-based
material that has been heated by the heated fluid to a temperature
above its glass transition temperature.
8. The method of claim 7, wherein the sheet of material is between
approximately 0.1 mm and 3 mm.
9. The method of claim 8, wherein the metallic glass-based material
that is heated above its glass transition temperature because of
the heated fluid is maintained at a temperature lower than its
crystallization temperature.
10. The method of claim 9, wherein deforming the metallic
glass-based material that has been heated by the heated fluid is
accomplished by using the heated fluid to deform the sheet of
material.
11. The method of claim 9, wherein deforming the metallic
glass-based material that has been heated by the heated fluid is
accomplished by pressing a shaping tool into the sheet of material
as it is supported, at least in part, by the heated fluid.
12. A method of shaping a sheet of material including a metallic
glass-based material comprising: moving a surface relative to a
sheet of material comprising a metallic glass-based material while
the surface and the sheet of material are in direct contact so as
to frictionally heat the metallic glass-based material within the
sheet of material above its glass transition temperature; wherein
the sheet of material has a thickness of between approximately 0.1
mm and approximately 10 mm; deforming the metallic glass-based
material that has been heated by the frictional heating to a
temperature above its glass transition temperature.
13. The method of claim 12, wherein the sheet of material has a
thickness of between approximately 0.1 mm and approximately 3
mm.
14. The method of claim 13, wherein the metallic glass-based
material that has been heated by the frictional heating is
maintained at a temperature lower than its crystallization
temperature during the frictional heating.
15. The method of claim 14, wherein moving the surface relative to
the sheet of material comprises rotating the surface relative to
the sheet of material so as to frictionally heat it.
16. The method of claim 15, wherein deforming the metallic
glass-based material is accomplished by pressing the surface into
the sheet of material.
17. The method of claim 16, wherein deforming the metallic
glass-based material is accomplished by pressing the surface into
the sheet of material so that it conforms to the shape of a mold
cavity.
18. The method of claim 14, wherein deforming the metallic
glass-based material is accomplished by using pressurized gas.
19. A method of shaping a sheet of material including a metallic
glass-based material comprising: deforming a metallic glass-based
material within a sheet of material at a temperature lower than the
glass transition temperature of the metallic glass-based material,
the metallic glass-based material having a volume fraction of
crystalline phase greater than approximately 30% and a fracture
toughness greater than approximately 80 MPam.sup.1/2; wherein the
sheet of material has a thickness of between approximately 0.1 mm
and approximately 10 mm.
20. The method of claim 19, wherein the metallic glass-based
material has a volume fraction of crystalline phase of greater than
approximately 40% and a fracture toughness greater than
approximately 100 MPam.sup.1/2.
21. The method of claim 20, wherein the sheet of material has a
thickness that is less than approximately three times the size of
the plastic zone radius of the metallic glass-based material.
22. The method of claim 21, wherein the sheet of material has a
thickness that is less than approximately one-third the size of the
plastic zone radius of the metallic glass-based material.
23. The method of claim 20, wherein the sheet of material has a
thickness of between approximately 0.1 mm and approximately 3
mm.
24. The method of claim 23, wherein deforming the metallic
glass-based material is accomplished using a pressing tool.
25. The method of claim 23, further comprising: removing portions
of the sheet of material in a periodic fashion; and deforming the
sheet of material that no longer includes the removed portions so
as to form a cellular structure.
26. The method of claim 25, wherein deforming the sheet of material
is accomplished using a punch and die.
27. The method of claim 23, wherein the metallic glass-based
material is
Zr.sub.55.3Ti.sub.24.9Nb.sub.10.8Cu.sub.6.2Be.sub.2.8.
28. A cellular structure comprising a metallic glass-based material
having a volume fraction of crystalline phase greater than
approximately 30% and a fracture toughness greater than
approximately 80 MPam.sup.1/2.
29. The cellular structure of claim 28, wherein the metallic
glass-based material has a volume fraction of crystalline phase
greater than approximately 40% and a fracture toughness greater
than approximately 100 MPam.sup.1/2.
30. The cellular structure of claim 28, wherein the metallic
glass-based material is
Zr.sub.55.3Ti.sub.24.9Nb.sub.10.8Cu.sub.6.2Be.sub.2.8.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The current application claims priority to U.S. Provisional
Application No. 61/811,405, filed Apr. 12, 2013, the disclosure of
which is incorporated herein by reference.
FIELD OF THE INVENTION
[0003] The present invention generally relates to shaping metallic
glass-based sheet material.
BACKGROUND
[0004] Metallic glasses, also known as amorphous alloys, embody a
relatively new class of materials that is receiving much interest
from the engineering and design communities. Metallic glasses are
characterized by their disordered atomic-scale structure in spite
of their metallic constituent elements--i.e. whereas conventional
metallic materials typically possess a highly ordered atomic
structure, metallic glass materials are characterized by their
disordered atomic structure. Notably, metallic glasses typically
possess a number of useful material properties that can allow them
to be implemented as highly effective engineering materials. For
example, metallic glasses are generally much harder than
conventional metals, and are generally tougher than ceramic
materials. They are also relatively corrosion resistant, and,
unlike conventional glass, they can have good electrical
conductivity. Importantly, the manufacture of metallic glass
materials lends itself to relatively easy processing in certain
respects. For example, the manufacture of a metallic glass can be
compatible with an injection molding process.
[0005] Nonetheless, the manufacture of metallic glasses presents
challenges that limit their viability as engineering materials. In
particular, metallic glasses are typically formed by raising a
metallic alloy above its melting temperature, and rapidly cooling
the melt to solidify it in a way such that its crystallization is
avoided, thereby forming the metallic glass. The first metallic
glasses required extraordinary cooling rates, e.g. on the order of
10.sup.6 K/s, and were thereby limited in the thickness with which
they could be formed. Indeed, because of this limitation in
thickness, metallic glasses were initially limited to applications
that involved coatings. Since then, however, particular alloy
compositions that are more resistant to crystallization have been
developed, which can thereby form metallic glasses at much lower
cooling rates, and can therefore be made to be much thicker (e.g.
greater than 1 mm). These metallic glass compositions that can be
made to be thicker are known as `bulk metallic glasses`
("BMGs").
[0006] In addition to the development of BMGs, `bulk metallic glass
matrix composites` (BMGMCs) have also been developed. BMGMCs are
characterized in that they possess the amorphous structure of BMGs,
but they also include crystalline phases of material within the
matrix of amorphous structure. For example, the crystalline phases
can exist in the form of dendrites. The crystalline phase
inclusions can impart a host of favorable materials properties on
the bulk material. For example, the crystalline phases can allow
the material to have enhanced ductility, compared to where the
material is entirely constituted of the amorphous structure. BMGs
and BMGMCs can be referred to collectively as BMG-based materials.
Similarly, metallic glasses, metallic glasses that include
crystalline phases of material, BMGs, and BMGMCs can be referred to
collectively as metallic glass-based materials or MG-based
materials.
[0007] Although considerable advances have been made in the
development of MG-based materials, they have yet to be developed to
an extent where they can truly be implemented as viable, widespread
engineering materials. Recently, efforts have been made to develop
MG-based feedstock that is in the form of conventional sheet metal,
e.g. a sheet of material having a thickness of between
approximately 0.1 mm and approximately 10 mm, and being
substantially planar otherwise. It is believed that such `MG-based
sheet materials` can lend themselves to conventional manufacturing
processes, and thereby facilitate the widespread implementation of
MG-based materials.
SUMMARY OF THE INVENTION
[0008] Systems and methods in accordance with embodiments of the
invention advantageously shape sheet materials that include
metallic glass-based materials. In one embodiment, a method of
shaping a sheet of material including a metallic glass-based
material includes: heating a metallic glass-based material within a
first region within a sheet of material to a temperature greater
than the glass transition temperature of the metallic glass-based
material; where the sheet of material has a thickness of between
approximately 0.1 mm and approximately 10 mm; where at least some
portion of the sheet of material does not include metallic
glass-based material that is heated above its respective glass
transition temperature when the metallic glass-based material
within the first region is heated above its respective glass
transition temperature; and deforming the metallic glass-based
material within the first region while the temperature of the
metallic glass-based material within the first region is greater
than its respective glass transition temperature.
[0009] In another embodiment, the sheet of material has a thickness
of between approximately 0.1 mm and approximately 3 mm.
[0010] In still another embodiment, the temperature of the metallic
glass-based material within the first region is maintained below
its crystallization temperature when it is heated above the glass
transition temperature.
[0011] In yet another embodiment, at least a majority of the sheet
of material, as measured by volume, does not include metallic
glass-based material that is heated above its respective glass
transition temperature when the metallic glass-based material
within the first region is heated above its respective glass
transition temperature.
[0012] In still yet another embodiment, heating the metallic
glass-based material within the first region is accomplished using
one of: induction heating, frictional heating, and a heated
fluid.
[0013] In a further embodiment, deforming the metallic glass-based
material within the first region is accomplished by pressing a
shaping tool into the sheet of material.
[0014] In a still further embodiment, a method of shaping a sheet
of material including a metallic glass-based material includes:
subjecting a sheet of material including a metallic glass-based
material to direct contact with a heated fluid so as to raise the
temperature of at least some portion of the metallic glass-based
material to a temperature that is above its glass transition
temperature; where the sheet of material has a thickness between
approximately 0.1 mm and 10 mm; and deforming the metallic
glass-based material that has been heated by the heated fluid to a
temperature above its glass transition temperature.
[0015] In a yet further embodiment, the sheet of material is
between approximately 0.1 mm and 3 mm.
[0016] In a still yet further embodiment, the metallic glass-based
material that is heated above its glass transition temperature
because of the heated fluid is maintained at a temperature lower
than its crystallization temperature.
[0017] In another embodiment, deforming the metallic glass-based
material that has been heated by the heated fluid is accomplished
by using the heated fluid to deform the sheet of material.
[0018] In yet another embodiment, deforming the metallic
glass-based material that has been heated by the heated fluid is
accomplished by pressing a shaping tool into the sheet of material
as it is supported, at least in part, by the heated fluid.
[0019] In still another embodiment, a method of shaping a sheet of
material including a metallic glass-based material includes: moving
a surface relative to a sheet of material including a metallic
glass-based material while the surface and the sheet of material
are in direct contact so as to frictionally heat the metallic
glass-based material within the sheet of material above its glass
transition temperature; where the sheet of material has a thickness
of between approximately 0.1 mm and approximately 10 mm; deforming
the metallic glass-based material that has been heated by the
frictional heating to a temperature above its glass transition
temperature.
[0020] In still yet another embodiment, the sheet of material has a
thickness of between approximately 0.1 mm and approximately 3
mm.
[0021] In a further embodiment, the metallic glass-based material
that has been heated by the frictional heating is maintained at a
temperature lower than its crystallization temperature during the
frictional heating.
[0022] In a still further embodiment, moving the surface relative
to the sheet of material includes rotating the surface relative to
the sheet of material so as to frictionally heat it.
[0023] In a yet further embodiment, deforming the metallic
glass-based material is accomplished by pressing the surface into
the sheet of material.
[0024] In a still yet further embodiment, deforming the metallic
glass-based material is accomplished by pressing the surface into
the sheet of material so that it conforms to the shape of a mold
cavity.
[0025] In another embodiment, deforming the metallic glass-based
material is accomplished by using pressurized gas.
[0026] In still another embodiment, a method of shaping a sheet of
material including a metallic glass-based material includes:
deforming a metallic glass-based material within a sheet of
material at a temperature lower than the glass transition
temperature of the metallic glass-based material, the metallic
glass-based material having a volume fraction of crystalline phase
greater than approximately 30% and a fracture toughness greater
than approximately 80 MPam.sup.1/2; where the sheet of material has
a thickness of between approximately 0.1 mm and approximately 10
mm.
[0027] In yet another embodiment, the metallic glass-based material
has a volume fraction of crystalline phase of greater than
approximately 40% and a fracture toughness greater than
approximately 100 MPam.sup.1/2.
[0028] In still yet another embodiment, the sheet of material has a
thickness that is less than approximately three times the size of
the plastic zone radius of the metallic glass-based material.
[0029] In a further embodiment, the sheet of material has a
thickness that is less than approximately one-third the size of the
plastic zone radius of the metallic glass-based material.
[0030] In a still further embodiment, the sheet of material has a
thickness of between approximately 0.1 mm and approximately 3
mm.
[0031] In a yet further embodiment, deforming the metallic
glass-based material is accomplished using a pressing tool.
[0032] In a still yet further embodiment, the method further
includes removing portions of the sheet of material in a periodic
fashion; and deforming the sheet of material that no longer
includes the removed portions so as to form a cellular
structure.
[0033] In another embodiment, deforming the sheet of material is
accomplished using a punch and die.
[0034] In still another embodiment, the metallic glass-based
material is
Zr.sub.55.3Ti.sub.24.9Nb.sub.10.8Cu.sub.6.2Be.sub.2.8.
[0035] In yet another embodiment, a cellular structure includes a
metallic glass-based material having a volume fraction of
crystalline phase greater than approximately 30% and a fracture
toughness greater than approximately 80 MPam.sup.1/2.
[0036] In still yet another embodiment, the metallic glass-based
material has a volume fraction of crystalline phase greater than
approximately 40% and a fracture toughness greater than
approximately 100 MPam.sup.1/2.
[0037] In a further embodiment, the metallic glass-based material
is Zr.sub.55.3Ti.sub.24.9Nb.sub.10.8Cu.sub.6.2Be.sub.2.8.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] FIG. 1 illustrates a method of shaping a sheet material
including a metallic glass-based material by instituting localized
thermoplastic deformation in accordance with an embodiment of the
invention.
[0039] FIG. 2 illustrates the temperature profile of a sheet of
material including a metallic glass-based material when the sheet
of material is subjected to localized heating in accordance with an
embodiment of the invention.
[0040] FIGS. 3A-3B depict shaping a sheet material including a
metallic glass-based material by instituting localized
thermoplastic deformation in accordance with an embodiment of the
invention.
[0041] FIGS. 4A-4F illustrate shaping a sheet material including a
metallic glass-based material into a pot-shaped structure by
instituting localized thermoplastic deformation in accordance with
an embodiment of the invention.
[0042] FIGS. 5A-5C illustrate using a heated shaping tool to
implement localized thermoplastic deformation in accordance with an
embodiment of the invention.
[0043] FIGS. 6A-6B illustrate using a line contact heater to
implement localized thermoplastic deformation in accordance with an
embodiment of the invention.
[0044] FIG. 7 illustrates a method of shaping a sheet material
including a metallic glass-based material by using a heated fluid
to heat the metallic glass-based material in accordance with an
embodiment of the invention.
[0045] FIGS. 8A-8C illustrate using a heated fluid to shape a sheet
of material including a metallic glass-based material in accordance
with an embodiment of the invention.
[0046] FIGS. 9A-9B illustrate shaping a sheet of material including
a metallic glass-based material using a bed of heated fluid in
accordance with an embodiment of the invention.
[0047] FIG. 10 illustrates a method of shaping a sheet material
including a metallic glass-based material by using frictional
heating to heat the metallic glass-based material in accordance
with an embodiment of the invention.
[0048] FIGS. 11A-11D illustrate frictionally heating a sheet of
material including a metallic glass-based material so as to shape
it in accordance with an embodiment of the invention.
[0049] FIGS. 12A-12B illustrate frictionally heating a sheet of
material including a metallic glass-based material so as to shape
it and using a mold cavity to support the shaping process in
accordance with an embodiment of the invention.
[0050] FIGS. 13A-13C illustrate frictionally heating a sheet of
material including a metallic glass-based material, and using a
separate mechanism to shape the heated sheet of material.
[0051] FIG. 14 depicts a DH1 metallic alloy that has be cold formed
in accordance with an embodiment of the invention.
[0052] FIG. 15 illustrates a method of cold-forming a sheet
material including a metallic glass-based material in accordance
with an embodiment of the invention.
[0053] FIGS. 16A-16C depict pressing a sheet of material including
a metallic glass-based material at a temperature less than the
glass transition temperature of the metallic glass-based material
in accordance with embodiments of the invention.
[0054] FIGS. 17A-17B depict cellular structures that can be created
using cold-forming techniques in accordance with embodiments of the
invention.
[0055] FIG. 18 illustrates cold-forming a sheet of material
including a metallic glass-based material so as to form a cellular
structure in accordance with an embodiment of the invention.
DETAILED DESCRIPTION
[0056] Turning now to the drawings, systems and methods for
advantageously shaping sheet materials that include metallic
glass-based materials are illustrated. In many embodiments, a
method of shaping a sheet of material that includes a metallic
glass-based material includes locally heating a region of the sheet
of material, the region including a metallic glass based-material,
such that the temperature of the metallic glass based-material that
is within the region is elevated to above its glass transition
temperature, and deforming the heated metallic glass-based material
into a desired configuration. In numerous embodiments, the sheet of
material has a thickness of between approximately 0.1 mm and 10 mm.
In many embodiments, a method of shaping a sheet of material that
includes a metallic glass-based material includes subjecting the
sheet of material to direct contact with a heated fluid so as to
raise the temperature of at least some portion of the metallic
glass-based material to a temperature above its glass transition
temperature, and deforming the metallic glass-based material while
it is heated above its glass transition temperature. In numerous
embodiments, a method of shaping a sheet of material that includes
a metallic glass-based material includes moving a surface relative
to the sheet of material while the surface and the sheet of
material are in direct contact so as to frictionally heat the
metallic glass-based material to a temperature above its glass
transition temperature, and deforming the metallic glass-based
material that has been heated by the frictional heating to a
temperature above its glass transition temperature.
[0057] The efforts to develop metallic glass-based materials so
that they can more viably be incorporated as engineering and/or
design materials has led to the development of metallic glass-based
materials in the form of conventional sheet metal. It is believed
that metallic glass-based materials in this form factor can more
easily lend themselves to conventional shaping processes, and can
thereby promote their practicality. For example, metallic
glass-based materials in the shape of conventional sheet metal can
act as feedstock for subsequent shaping processes, e.g. those
commonly used to form conventional metallic components. As one
example, Prest et al. disclose a method for forming amorphous alloy
sheets including pouring molten metal so that it forms a sheet,
floating the sheet of molten metal on a second molten metal,
cooling the sheet of molten metal to form a metallic glass, and
annealing the sheet without deteriorating its metallic glass
qualities in U.S. Pat. No. 8,485,245. The disclosure of U.S. Pat.
No. 8,485,245 is hereby incorporated by reference in its
entirety.
[0058] Although sheets of metallic glass-based material have been
formed, they are typically still not entirely compatible with
conventional shaping processes. For example, while metallic glasses
may be relatively tough compared to conventional glasses, they may
not be tough enough to withstand a conventional folding operation,
e.g. one that a conventional metal may be able to withstand. In
essence, sheets of metallic glass-based are not universally
compatible with conventional forming/shaping operations. Instead,
methods for forming a metallic glass-based sheet material typically
involve heating the sheet so that it may be thermoplastically
formed/shaped. For example, in U.S. Pat. No. 8,613,815, Johnson et
al. disclose using a rapid capacitor discharge to heat an amorphous
alloy sample above its glass transition temperature and
simultaneously thermoplastically forming/shaping the sample. The
disclosure of U.S. Pat. No. 8,613,815 is hereby incorporated by
reference in its entirety. However, it is not clear that using a
rapid capacitor discharge can be effective for example to heat a
sheet of material based on a bulk metallic glass matrix composite
that includes crystalline phases beyond some threshold extent.
Instead, the crystalline inclusions may inhibit the heating effect
of the rapid capacitive discharge.
[0059] Additionally, Jan Schroers et al. have disclosed the
thermoplastic blow molding of metallic glass sheet materials to
form/shape them; these techniques essentially regard the heating of
the metallic glass sheet above the glass transition temperature,
and thereafter shaping them using conventional blow molding
techniques. Nonetheless, the techniques presently known for shaping
metallic glass-based sheet materials may not be inefficient and
non-optimal in a variety of circumstances. Accordingly, the instant
application discloses further methods that can more efficiently
shape metallic glass sheet material, and can thereby make metallic
glass-based material an even more viable option as an engineering
material.
[0060] For example, in some embodiments, metallic glass-based sheet
material is heated only where deformation is to occur (as opposed
to the entire metallic glass-based sheet material being heated). In
this way, the risk of adversely impacting the material properties
of the sheet material with unnecessary heating can be mitigated. In
a number of embodiments, a heated hydraulic fluid is used to heat a
metallic glass-based sheet material above its glass transition
temperature; the hydraulic fluid can then be used in the
shaping/forming of the metallic glass sheet material. Using heated
hydraulic fluid in the shaping of metallic glass sheet material can
be an effective shaping method insofar as the fluid can provide
substantial pressure to the metallic glass sheet material and cause
it to conform to unique mold cavity geometries that may be
difficult to accomplish otherwise. In several embodiments, a
metallic glass sheet material is frictionally heated to above its
glass transition temperature; the tool causing the frictional
heating may then be used to shape the metallic glass sheet
material. In this way, cooling can be quickly initiated by removing
the tool. Quickly initiating the cooling stage is important in
maintaining the amorphous structure of the metallic glass-based
material. In many embodiments, a method of shaping a metallic glass
sheet material involves shaping the metallic glass-based sheet
material at room temperature--this can be achieved when the
metallic glass-based sheet material has the requisite materials
properties. These processes are now discussed in greater detail
below.
Shaping Processes Incorporating Localized Thermoplastic
Deformation
[0061] In many embodiments, metallic glass-based sheet materials
are shaped by heating only those regions of the sheet where
thermoplastic deformation is to take place. In this way the
unnecessary heating of the remainder of the sheet material can be
avoided. Avoiding the unnecessary heating of the remainder of the
sheet material can confer a number of benefits. For example, in
general, heating metallic glass-based materials to a temperature
where they can be thermoplastically formed (e.g. above their glass
transition temperatures) carries with it the risk of inadvertently
heating the metallic glass-based materials to a temperature above
the crystallization temperature, thereby causing the metallic-glass
based material to crystallize and lose its glass-like qualities.
Moreover, heating metallic glass-based materials additionally
carries the risk of causing unwanted oxidation. Accordingly, by
avoiding unnecessarily heating the sheet material where heating is
not required, the risk of adversely affecting the material
properties is correspondingly reduced. Moreover, avoiding the
unnecessary heating can allow the shaping process to be more energy
efficient, e.g. energy is not needed to heat the entire sheet
material--only those portions that embody the deformation.
[0062] FIG. 1 illustrates a process for shaping a metallic
glass-based sheet material that includes locally heating and
deforming the sheet material in accordance with embodiments of the
invention. In particular, the process 100 includes heating 102 a
metallic glass-based material that is within a region within a
sheet of material to a temperature greater than the glass
transition temperature of the metallic glass based material. Note
that the sheet of material can be of any dimensions. As can be
appreciated, sheet materials are typically substantially planar and
have a characteristic thickness. The characteristic thickness can
be of any suitable dimensions. In many embodiments, sheets having a
thickness of between approximately 0.1 mm and approximately 10 mm
are implemented in the process. In numerous embodiments, sheets
having a thickness of between approximately 0.1 mm and 3 mm are
implemented. Notably, in many embodiments, the sheet of material is
entirely constituted of a single metallic glass-based material. In
a number of embodiments, the sheet of material is constituted of a
first metallic glass-based material and at least a second metallic
glass-based material. In several embodiments, the sheet of material
is constituted of a metallic glass-based material in conjunction
with another material. Generally, any suitable sheet of material
that includes a metallic-glass based material can be implemented in
accordance with embodiments of the invention.
[0063] Additionally, the metallic glass-based material within a
region can be heated 102 using any suitable technique in accordance
with embodiments of the invention. For example, in many
embodiments, the metallic glass-based material within the region is
heated using induction heating. In a number of embodiments, the
metallic glass-based material within the region is heated using a
heated fluid. In many embodiments, the metallic glass-based
material is heated frictionally. In general, any suitable method of
heating the metallic glass-based material within the region can be
implemented.
[0064] In numerous embodiments, at least some portion of the sheet
material is maintained at a temperature lower than the glass
transition temperature of the heated metallic-glass based material.
In several embodiments, at least some of the metallic glass-based
material within the sheet of material is at a temperature lower
than its respective glass transition temperature when the metallic
glass-based material within the region is heated above its
respective glass transition temperature. In many embodiments, at
least some portion of the sheet material is maintained at a lower
temperature than the lowest glass transition temperature amongst
any of the metallic glass-based materials that are present in the
sheet of material. In a number of embodiments, the majority of the
sheet material (e.g. as measured by volume, or alternatively, by
surface area) does not include metallic glass-based material that
is above its respective glass transition temperature when the
metallic glass-based material within the region is heated to above
its glass transition temperature. In several embodiments, the
majority of the sheet of material is maintained at a temperature
lower than the lowest glass transition temperature of any of the
metallic glass-based materials that are present in the sheet of
material. In many embodiments, the temperature of the metallic
glass-based material is kept below the crystallization
temperature.
[0065] FIG. 2 depicts a schematic illustration of the temperature
as a function of location along a length of a sheet of material
that is entirely constituted of a single metallic glass-based
material. In particular, it is illustrated that only a certain
region of the sheet of material is heated above the glass
transition temperature of the metallic glass-based material. Thus,
as can be appreciated, this region of the sheet can be
thermoplastically formed, whereas the other portions are not
amenable to thermoplastic forming.
[0066] Returning back to FIG. 1, the method 100 further includes
deforming 104 the metallic glass based-material within the region
while it has been heated 102 above the glass transition temperature
of the metallic glass-based material. In other words, the method
100 involves thermoplastically forming the sheet of material. The
metallic glass based material can be deformed 104 in any suitable
way in accordance with embodiments of the invention. For example,
the metallic glass-based material can be folded, stamped,
corrugated, etc. In general, any method of contorting the heated
metallic glass-based material in the region can be implemented.
Thus, using this method, metallic glass-based sheet material can be
more efficiently shaped.
[0067] FIGS. 3A and 3B depict the local heating and deformation of
a sheet material in accordance with embodiments of the invention.
In particular, FIG. 3A depicts a sheet of material 302 including a
first region 304, that itself includes a metallic glass-based
material. The first region 304 is heated by an induction coil 306
so that the temperature of the residing metallic glass-based
material is elevated to above its glass transition temperature.
FIG. 3B depicts a tool 308 that is used to apply an upward force on
the sheet of material 302 while the first region 304 is heated so
as to cause the thermoplastic deformation of the metallic
glass-based material in the region 304 in accordance with
embodiments of the invention. Note that in the illustrated
embodiment, the remainder of the sheet of material is not
unnecessarily heated as it is not intended to be thermoplastically
formed. Of course, as can be appreciated, while FIGS. 3A and 3B
depict an induction coil heater, the metallic glass-based material
within the region can be heated using any suitable technique in
accordance with embodiments of the invention.
[0068] Although FIGS. 3A-3B depict the folding of a metallic
glass-based sheet material, a sheet of material including metallic
glass-based materials can be thermoplastically formed in any
suitable way in accordance with embodiments of the invention. For
example, FIGS. 4A-4E illustrate that pot shaped structures can be
formed from metallic glass-based sheet materials in accordance with
embodiments of the invention. In particular, FIG. 4A depicts the
general shape of pots, which can be characterized by a principal
bend adjoining the bottom of the pot and its walls. FIG. 4B depicts
the general setup that can be used to form a pot-shaped structure
in accordance with embodiments of the invention. In particular,
FIG. 4B depicts a metallic glass-based sheet material 402 being
supported by a cylindrical structure 408 that is thermally
conductive. The sheet of material 402 is also held in place by
structure 410. Induction coils 406 are used to heat the thermally
conductive cylindrical structural 408. Regions 404 are highlighted
as the target areas for the thermoplastic deformation. The
Induction coils 406 are used to heat the thermally conductive
structure 408 so that the region 404 of the sheet of material 402
can be heated to above the glass transition temperature. Bear in
mind that FIG. 4B illustrates a cross-sectional view of the set
up--as can be appreciated, the illustration is meant to communicate
circular geometries. For purposes of clarity, FIG. 4C depicts an
isometric view of setup. The structure 410 and the induction coils
406 are omitted in FIG. 4C for purposes of clarity.
[0069] FIG. 4D depicts that a cylindrical tool 412 is used to shape
the metallic glass based sheet material 402 while the region 404
has been has been heated so that its constituent metallic
glass-based material is above its glass transition temperature. In
particular, the cylindrical tool 412 is pressed into the sheet
material to shape it. The heated region 404 can accommodate the
thermoplastic shaping that can enable the creation of the
structure.
[0070] FIG. 4E depicts the shape of the sheet material 402 after it
has been treated, and FIG. 4F depicts that the remainder of the
sheet material may be separated from the pot-shaped structure.
[0071] In some embodiments, the tool that is used to heat metallic
glass-based material within a sheet is also used to shape the sheet
material. FIGS. 5A-5C illustrate a method of shaping metallic
glass-based sheet material, whereby a tool in the shape of a
parabolic head is used to both heat the metallic glass-based
material within a sheet to above its glass transition temperature
and shape metallic glass-based sheet material. In particular, FIG.
5A depicts the metallic glass-based sheet material 502 along with a
parabola-shaped tool 506 that is used to shape the metallic
glass-based sheet material. The tool 506 is also used to heat a
region of the sheet of material to a temperature above the glass
transition temperature of its constituent metallic glass-based
material. For example, the tool 506 itself can be heated, and
thereby heat the sheet of material through conduction.
Alternatively, the parabola-shaped tool 506 can be spun about its
central axis against the sheet of material to generate frictional
heating, and thereby heat the metallic glass-based sheet material
502 to the requisite temperature. FIG. 5B depicts that the tool 506
has been used to thermoplastically shape the sheet of material 502
as it has been heated above the requisite glass transition
temperature. Note that the tool 506 is not in direct contact with
any other portion of the sheet of material so that the remaining
portions of the sheets of material are not necessarily heated above
the aforementioned glass transition temperature. FIG. 5C depicts
that, as before, the desired shape can be separated from the sheet
material 502.
[0072] While the above illustrations depict that a cylindrical tool
having a relatively large diameter is used to shape the metallic
glass-based sheet material, it should be clear that a tool of any
shape can be used to shape the sheet material object. For example,
in some embodiments a line contact heater is used to heat and
thermoplastically shape the sheet material. FIGS. 6A-6B depict
shaping a sheet material with a line contact heater in accordance
with embodiments of the invention. In particular, FIG. 6A depicts a
sheet of material 602 supported by structures 610, 612. A line
contact heater 608 is the tool that is used to form the sheet of
material 602. The line contact heater is heated with induction
coils 606. FIG. 6B depicts the shaping of the sheet of material 602
using the line contact heater 608. Note that the final shape of the
shaped sheet metal will depend on a variety of parameters
including: to what extent the metallic glass-based material was
heated above its glass transition temperature, the force with which
the line contact heater is applied to the sheet material, and the
length of time that the sheet material is exposed to the line
contact heater. As can be appreciated, any of these parameters can
be varied to control the final shape of the sheet material.
[0073] The localized thermoplastic shaping techniques described
above can be implemented and modified in any of a variety of ways
in accordance with embodiments of the invention. For example, any
of a variety of shaping tools can be used to shape heated metallic
glass-based sheet materials. In some embodiments, a plurality of
regions within a sheet of material including metallic glass-based
materials are simultaneously thermoplastically shaped. It should
also be appreciated that the sheet of material can include any
suitable metallic glass-based material in accordance with
embodiments of the invention, and is not limited to a particular
subset of metallic glass-based materials. Generally, any of a
variety of modifications to the above described techniques can be
implemented in accordance with embodiments of the invention.
Additionally, while the above discussion has focused on
advantageously shaping sheet material including metallic
glass-based materials using localized thermoplastic forming
techniques, in many embodiments, fluids are used to
thermoplastically form a sheet of material including metallic
glass-based materials. These processes are now described in greater
detail below.
Using Fluids in the Thermoplastic Shaping of Sheet Materials
[0074] In many embodiments, fluids are used to thermoplastically
shape a sheet of material that includes a metallic glass-based
material. In a number of embodiments, heated fluids are used to
elevate the temperature of the constituent metallic glass-based
material to above its respective glass transition temperature. Any
fluid capable of heating a sheet of material including metallic
glass-based material above the glass transition temperature of the
metallic glass-based material can be utilized in accordance with
embodiments of the invention. For example, in some embodiments,
molten metal is used as the heating fluid. In a numerous
embodiments, a conventional hydraulic fluid is used. In several
embodiments, a heating oil is used. In a number of embodiments, a
heating gas is used. In general, any suitable fluid that can heat a
sheet of material including metallic glass-based materials can be
utilized in accordance with embodiments of the invention. In many
instances, it is simply required that the fluid be able to heat the
sheet material to a temperature that is greater than approximately
350.degree. C. The heated fluid can thereafter be used to apply
pressure to the sheet of material and thereby cause it to conform
to the shape of a tool. Using fluids in this manner can be
advantageous insofar as fluids can more uniformly apply heat and
pressure to a sheet of material against a tool irrespective of the
tool geometry. For example, where a sheet of material is to be
shaped by a curved tool, the liquid can more easily cause it to
uniformly conform to the shape of the curvature. In general, the
fluid can be used in conjunction with any shaping tool to shape the
sheet of material in accordance with embodiments of the
invention.
[0075] FIG. 7 depicts one method of shaping a sheet of material
including a metallic glass-based material using a heated fluid in
accordance with embodiments of the invention. In particular the
method 700 includes heating 702 metallic glass-based material
within a sheet of material using a fluid to a temperature greater
than the glass transition temperature of the metallic glass-based
material. As alluded to above, any suitable heating fluid can be
implemented. The method 700 further includes deforming 704 the
metallic glass-based material that has been heated by the heated
fluid. Again, as previously alluded to, the deformation 704 can be
achieved using any suitable technique.
[0076] For example, in some embodiments, a shaping tool having a
semi-circular cross section is used to shape a sheet of material
including a metallic glass-based material in accordance with
embodiments of the invention. FIGS. 8A-8C depict how such a heated
fluid can be used in conjunction with such a shaping tool to shape
a metallic glass-based sheet material in accordance with
embodiments of the invention. In particular, FIG. 8A illustrates an
initial setup that includes a sheet of material 802 including a
metallic glass-based material, a fluid 804 that heats the sheet of
material 802 to above the glass transition temperature of the
constituent metallic glass-based material so that it can be
thermoplastically shaped, and a mold 806 which shapes the sheet of
material 802. The sheet of material 802 is held in place by
supporting blocks 808. FIG. 8B depicts the thermoplastic shaping of
sheet of material 802 by using the fluid 804 to apply sufficient
pressure (e.g., 10,000 psi) to cause the sheet 802 to conform to
the shape of the mold 806 after the temperature of the constituent
metallic glass-based material is elevated to above its glass
transition temperature. As alluded to above, the fluid can
uniformly apply pressure to the sheet against the mold 806, and
thereby more precisely cause the formation of the desired shape.
FIG. 8C depicts the shape of the sheet 802 after the process. As
mentioned above, any suitable heating fluid can be used in
accordance with this process. Additionally, although a mold having
a semi-circular shape has been illustrated, it should clear that
any shaping tool can be incorporated. Indeed, the
interchangeability of the shaping tools is one of the advantages of
the described process.
[0077] While FIGS. 8A-8C depict using a liquid to force a sheet of
material against a shaping tool, in many embodiments a shaping tool
is used to force a sheet of material against a heated fluid. For
example, FIGS. 9A-9B depict shaping a sheet of material including
metallic glass-based material by using a shaping tool to force the
sheet of material against a bed of heated liquid in accordance with
embodiments of the invention. In particular, FIG. 9A depicts an
initial setup that includes a sheet of material 902 including
metallic glass-based material disposed above a bed of heated fluid
904. The container housing the heated fluid includes reservoir
regions 908. A shaping tool 906 is seen above the sheet of material
902. FIG. 9B depicts that she shaping tool 906 forces the sheet of
material 902 into the bed of heated fluid 904 to shape it. As
before, the heated fluid 904 can uniformly apply pressure to the
sheet of material 902 against the shaping tool 906. As can be
appreciated, the heated fluid elevates the temperature of the
metallic glass-based material within the sheet of material 902 to
above the glass transition temperature so that it can be
thermoplastically formed. Notably, the reservoirs 908 accommodate
the displaced fluid and thereby facilitate the shaping process.
Thus, it is demonstrated how the heated fluid can support a sheet
of material while it is being shaped by a distinct shaping
tool.
[0078] Of course, it should be appreciated that the above-described
processes can be varied in any of a variety of ways in accordance
with embodiments of the invention. For example, as previously
mentioned, any of a variety of fluids can be implemented, and the
fluids do not necessarily have to be liquid--they can be gaseous.
Similarly, any of a variety of shaping tools can be used in
conjunction with the above-described processes. Additionally, in
some embodiments, the fluid does not heat the sheet of material
above the glass transition temperature of the constituent metallic
glass-based material; instead the sheet of material is separately
heated (e.g. using an induction heater), and the fluid is used to
thermoplastically shape the separately heated material sheet. In a
number of embodiments, the fluid is used in conjunction with
another mechanism (e.g. an induction heater) to heat the sheet of
material above the glass transition temperature of the constituent
metallic glass-based material. The sheet of material can thereby be
thermoplastically formed. Of course it should be appreciated that
the above techniques can be applied in conjunction with any of a
variety of suitable metallic glass-based materials--the process is
not limited to a particular subset of metallic glass-based
materials. While the above discussion has regarded using fluids in
conjunction with the thermoplastic shaping of a sheet of material
including a metallic glass-based material, in many embodiments, a
sheet of material including metallic glass-based materials is
heated frictionally above the relevant glass transition temperature
so that it can be thermoplastically formed. These processes are now
discussed in greater detail below.
Shaping Processes Incorporating Frictional Heating
[0079] In many embodiments of the invention, a sheet of material
including metallic glass-based materials is heated frictionally so
that they may be thermoplastically shaped. Incorporating frictional
heating in thermoplastic shaping processes can be advantageous
insofar as the subsequent cooling of the material can be initiated
efficiently and virtually immediately with the removal of the
friction-causing mechanism. Recall that cooling rates play a vital
role in allowing a metallic glass-based material to retain its
amorphous structure. Frictional heating can be instituted using any
of a variety of processes in accordance with embodiments of the
invention. For example, in many embodiments, a surface is rapidly
rotated while in direct contact with a sheet of material including
a metallic glass-based material so as to raise the temperature of
the metallic glass based material above the relevant glass
transition temperature. In a number of embodiments, frictional
heating is effectuated by translational sliding of a surface with
the material sheet. In many embodiments, the surface is the shaping
tool that is used to thermoplastically shape the material sheet. In
general, any mechanism for frictionally heating the sheet of
material can be incorporated in accordance with embodiments of the
invention.
[0080] FIG. 10 depicts one method of shaping a sheet of material
including a metallic glass-based material by using frictional
heating in accordance with embodiments of the invention. In
particular, the method 1000 includes sliding 1002 a surface
relative to a sheet of material that includes a metallic
glass-based material while the surface and the sheet of material
are in direct contact so as to frictionally heat the metallic
glass-based material to a temperature above its glass transition
temperature. As alluded to above, the relative motion can be
achieved in any suitable way including by rotating the surface
against the sheet of material and by translating the surface
against the sheet of material. The method 1000 further includes
deforming 1004 the metallic glass-based material that has been
heated by the frictional heating. As can be appreciated, any method
of deformation 1004 can be implemented. For example the surface
that causes the friction can be pressed into the sheet of material.
In some embodiments, a distinctly different surface (e.g. not the
surface that causes friction) is used to cause the deformation. In
a number of embodiments a gas is used to cause the deformation. In
general, any suitable technique for causing the deformation can be
implemented in accordance with embodiments of the invention.
[0081] FIGS. 11A-11D depict shaping a sheet of material including a
metallic glass-based material using frictional heating caused by a
shaping tool that incorporates a parabola-shaped head in accordance
with embodiments of the invention. In particular, FIG. 11A depicts
the initial setup for the process that includes a sheet of material
1102 that itself includes a metallic glass-based material being
supported by structures 1110. The shaping tool 1104 includes a
parabola-shaped head, and is shown rotatable about its central
axis, so that it can generate the requisite friction to elevate the
temperature of the constituent metallic glass-based material above
its glass transition temperature. FIG. 11B depicts the direct
contact between the shaping tool 1104 and the sheet of material
1102 while the shaping tool 1104 is spinning, so as to generate
frictional heating. FIG. 11C depicts that the shaping tool has
further penetrated the sheet of material 1104 because of the
thermoplastic shaping process; note that with greater penetration
of the sheet of material, there is more surface area in direct
contact between the shaping tool 1104 and the sheet of material
1102, and correspondingly more frictional heating. FIG. 11D depicts
the resulting shape of the sheet of material 1102 after the
processing. As can be inferred from the illustrations, frictional
heating can be used to locally thermoplastically shape sheets of
material, as the frictional heating can be relatively
localized.
[0082] Although the above description and accompanying illustration
depicts the using a shaping tool to shape the metallic glass sheet
without the support of a mold cavity, in many embodiments a mold
cavity is also used to help shape the sheet of material. FIGS.
12A-12B depict using a mold cavity in conjunction with a
cylindrical shaping tool to help shape a sheet of material in
accordance with embodiments of the invention. In particular, FIGS.
12A-10B are similar FIGS. 12A-12C, except they further depict a
mold cavity 1212 that accommodates the deformation caused by the
shaping tool.
[0083] While the above descriptions have regarded scenarios where
the shaping tool is also used to provide frictional heating, in
many embodiments the friction causing mechanism and the shaping
mechanism are distinct. For example, FIGS. 13A-13C depict that a
pressure difference is used to thermoplastically shape a sheet of
material after it has been frictionally heated. In particular, FIG.
13A depicts an initial setup that includes a sheet of material 1302
supported by a structure 1310, a friction causing surface 1304, as
well as a mold cavity 1312. As before, the friction causing surface
is rotatable about its central axis, and can thereby generate
friction. FIG. 13B depicts that the friction causing surface 1304
frictionally heats the sheet of material 1302 to a temperature
above the relevant glass transition temperature. FIG. 13C depicts
that an imposed pressure difference between the region outside of
the mold cavity 1312 and the mold cavity can cause the desired
deformation. For example, the region outside the mold cavity can be
filled with pressurized gas to cause the sheet material to conform
to the mold cavity 1312. Although, a pressure differential is used
to cause the desired shaping, it should be clear that any shaping
technique can be used in conjunction with frictional heating in
accordance with embodiments of the invention. For example, a
distinct pressing mechanism can be implemented.
[0084] In general, similar to before, the above-described
processing techniques can be modified in any of a variety of ways
in accordance with embodiments of the invention. While the above
processes have largely regarded the thermoplastic shaping of
metallic glass-based sheet materials, in many embodiments, shaping
processes for cold-forming sheet materials including metallic-glass
based materials that include crystalline inclusions are
implemented, and these are now discussed in greater detail
below.
Cold-Forming of Sheet Materials Comprising Metallic-Glass Based
Materials that Include Crystalline Inclusions
[0085] Metallic glass-based materials are typically characterized
as somewhat brittle (at least relative to conventional engineering
metals such as steel), and their shaping largely revolves around
thermoplastic deformation. However, in many embodiments of the
invention, metallic glass-based materials that include crystalline
inclusions undergo shaping procedures at temperatures below the
respective glass transition temperature. In effect, the crystalline
inclusions impart sufficient ductility to allow for such
`cold-forming.` In many embodiments, the constituent metallic
glass-based material includes greater than approximately 30%
crystalline inclusions (by volume) and has a fracture toughness of
greater than approximately 80 MPam.sup.1/2. In a number of
embodiments, the constituent metallic glass-based material includes
greater than approximately 40% crystalline inclusions (by volume)
and has a fracture toughness greater than approximately 100
MPam.sup.1/2. These characteristics can impart sufficient toughness
to the sheet material to allow it to be cold formed. As an example,
FIG. 14 depicts the cold-forming of a DH1 alloy
(Zr.sub.55.3Ti.sub.24.9Nb.sub.10.8Cu.sub.6.2Be.sub.2.8) in
accordance with embodiments of the invention. Note that the
material survived the bending without brittle failure. The depicted
sheet had a thickness of 0.8 mm. In many embodiments, the thickness
of the sheet material is less than approximately three times the
size of the plastic zone radius of the constituent metallic
glass-based material. In many embodiments, the thickness of the
sheet material is less than approximately 1/3 the size of the
plastic zone radius of the constituent metallic glass-based
material. In essence, contrary to conventional wisdom, metallic
glass-based materials can be made to withstand cold-forming
operations.
[0086] FIG. 15 depicts one method of cold-forming a sheet of
material including a metallic glass-based material in accordance
with embodiments. In particular, the method 1500 includes deforming
1502 a metallic glass-based material within a sheet of material at
a temperature lower than the glass transition temperature of the
metallic glass-based material, the metallic glass-based material
having a volume fraction of crystalline phase greater than
approximately 30% and a fracture toughness greater than
approximately 80 MPam.sup.1/2. As mentioned previously, these
characteristics can impart sufficient toughness to the metallic
glass-based material to allow it to survive cold-forming
operations. Additionally, as can be appreciated, any suitable
cold-forming operation can be implemented on metallic glass-based
sheet materials having sufficient toughness. For example, FIGS.
16A-16C depict a pressing operation that can be implemented in
accordance with embodiments of the invention. In particular, FIG.
16A depicts the initial setup that includes metallic glass-based
sheet material that includes at least approximately 30% crystalline
inclusions (by volume) 1602, a pressing tool, 1604, supporting
structures 1610, 1612, and a mold cavity 1614. Importantly, the
constituent metallic glass-based material has a fracture toughness
of greater than approximately 80 MPam.sup.1/2. FIG. 13B depicts
that the press 1602 is used to shape the sheet material 1602 at a
temperature less than the glass transition temperature of the
constituent metallic glass-based material. The material properties
of the metallic glass-based sheet material (e.g. its toughness)
allow it to survive the pressing operation. FIG. 16C depicts that
the mold cavity 1614 can move with the press 1604 to relax excess
pressure. As can be appreciated, FIGS. 16A-16C are akin to a deep
drawing process.
[0087] It should of course be clear that any of a variety of
forming operations can be implemented in accordance with
embodiments of the invention. For example, in many embodiments, the
sheet materials are formed using stamping tools. In a number of
embodiments, they are formed with water jets. In several
embodiments, lasers are used to shape the structures. In general,
any of a variety of shaping procedures can be implemented.
[0088] Notably, the above-described processes can be used to create
any of a variety of geometries. For example, in many embodiments,
cellular structures are created. FIGS. 17A-17B depict cellular
geometries that may be created by cold-forming sufficiently tough
sheet materials that include metallic glass-based materials in
accordance with embodiments of the invention. Cellular structures
are often desired for their energy absorbing capabilities. Indeed,
whereas cellular structures are typically fabricated from
conventional engineering materials, cellular structures fabricated
from tough metallic glass-based materials can demonstrate enhanced
energy absorbing traits.
[0089] FIG. 18 depicts using a punch and die to form a 3D cellular
structure in accordance with embodiments of the invention. In
particular, it is illustrated that a sheet 1802 being constituted
of a metallic glass-based material has been pre-formed so that it
includes a series of diamond-shaped holes, thereby adopting a
`fence-like` shape. In other words, portions of the sheet material
have been removed in a periodic fashion to form the fence-like
shape. The portions can be removed using any suitable technique in
accordance with embodiments of the invention. For instance, water
jets can be used to carve out the diamond-shaped holes;
alternatively, lasers can be used. As can be appreciated, the
metallic glass-based material can be any such material having
greater than approximately 30% crystalline inclusions (by volume)
and a fracture toughness of greater than approximately 80
MPam.sup.1/2. A punch 1804 and die 1806 are used to add a vertical
dimension to the sheet 1802 and thereby create a cellular
structure. As can be appreciated, the toughness of the metallic
glass-based material can allow it to withstand the cold-forming
operation. Thus, it is seen that 3D cellular structures can be
efficiently made in accordance with embodiments of the
invention.
[0090] As can be inferred from the above discussion, the
above-mentioned concepts can be implemented in a variety of
arrangements in accordance with embodiments of the invention.
Accordingly, although the present invention has been described in
certain specific aspects, many additional modifications and
variations would be apparent to those skilled in the art. It is
therefore to be understood that the present invention may be
practiced otherwise than specifically described. Thus, embodiments
of the present invention should be considered in all respects as
illustrative and not restrictive.
* * * * *