U.S. patent application number 11/285853 was filed with the patent office on 2007-11-15 for method of forming a structural component having a nano sized/sub-micron homogeneous grain structure.
This patent application is currently assigned to General Electric Company. Invention is credited to Judson Sloan Marte, Ramkumar Kashyap Oruganti, Pazhayannur Ramanathan Subramanian.
Application Number | 20070261458 11/285853 |
Document ID | / |
Family ID | 37685190 |
Filed Date | 2007-11-15 |
United States Patent
Application |
20070261458 |
Kind Code |
A1 |
Oruganti; Ramkumar Kashyap ;
et al. |
November 15, 2007 |
METHOD OF FORMING A STRUCTURAL COMPONENT HAVING A NANO
SIZED/SUB-MICRON HOMOGENEOUS GRAIN STRUCTURE
Abstract
A method of making nano/sub-micron sized grains in a work piece
material having a lateral side has the steps of providing a die.
The die has an entrance channel with a longitudinal axis and an
exit channel. The entrance channel and the exit channel are
connected to one another to form an angle. The method has the step
of providing a first sacrificial material with a complementary size
to the work piece and placing the sacrificial first material and
the work piece in an entrance channel. The first sacrificial
material and the work piece are aligned with the longitudinal axis.
The method has the step of extruding the combination of the first
sacrificial material, and the work piece through the intersection
of the entrance and the exit channels. The resulting shear
deformation forms the nano/sub-micron sized grains in the work
piece. This configuration reduces frictional effects thereby
producing homogenous nano grain structure. This configuration
reduces applied load and enables equal channel angular extrusion of
thin sheets.
Inventors: |
Oruganti; Ramkumar Kashyap;
(Karnataka, IN) ; Ramanathan Subramanian;
Pazhayannur; (Niskayuna, NY) ; Marte; Judson
Sloan; (Wynantskill, NY) |
Correspondence
Address: |
Paul J. DiConza;General Electric Global Research
One Research Circle
Docket Room K1-4A59
Niskayuna
NY
12309
US
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
37685190 |
Appl. No.: |
11/285853 |
Filed: |
November 22, 2005 |
Current U.S.
Class: |
72/253.1 |
Current CPC
Class: |
B21C 23/22 20130101;
B21C 23/002 20130101; B21C 23/001 20130101 |
Class at
Publication: |
072/253.1 |
International
Class: |
B21C 23/00 20060101
B21C023/00 |
Claims
1. A method for processing a work piece having a front end, a back
end, and a plurality of lateral sides, the method comprising:
providing a die, said die having an entrance channel with a
longitudinal axis and an exit channel, said entrance channel and
said exit channel being connected to one another; disposing a first
sacrificial material between said die and at least one lateral side
of the work piece while leaving the front end and back end
substantially free from contacting said first sacrificial material;
and extruding said first sacrificial material and said work piece
through said exit channel.
2. (canceled)
3. The method of claim 1, wherein all of the plurality of lateral
sides are in contact with said first sacrificial material.
4. The method of claim 1, wherein said first sacrificial material
and the work piece are each substantially orthogonal shaped members
having a flat mating surface.
5. The method of claim 1, wherein the work piece is selected from
the group consisting of nickel, a nickel alloy, a nickel base
alloy, a nickel base alloy being strengthened by a precipitate,
nickel base alloy being strengthened by a gamma prime precipitate,
a nickel based super alloy, a co-base super alloy, an oxide
dispersion strengthened alloy, a multi-layered combination of
materials, an iron based alloy, and an aluminum based alloy, a
titanium, a titanium alloy, and any combination thereof
6. The method of claim 1, wherein said first sacrificial material
is selected from the group consisting of carbon, graphite,
aluminum, an aluminum alloy, a copper, and a copper alloy.
7. The method of claim 1, wherein sub-micron sized grains are
formed in the work piece and are disposed in a substantially
homogenous fashion throughout a cross section of the work
piece.
8. The method of claim 1, wherein said first sacrificial material
surrounds the work piece in a manner to reduce friction between the
work piece during extrusion, and further comprising the step of
optionally repeating extrusion of said first sacrificial material
and the work piece through said die.
9. The method of claim 1, wherein said first sacrificial material
has the same flow stress as the work piece.
10. The method of claim 1, wherein said first sacrificial material
and said die have a first coefficient of friction at an interface
therebetween, said first coefficient of friction being different
relative to a second coefficient of friction being between a second
interface between said die and the work piece.
11. The method of claim 1, wherein said first sacrificial material
and the work piece substantially fill said entrance channel.
12. The method of claim 1, wherein said first sacrificial material
and the work piece substantially fill said exit channel.
13. The method of claim 1, wherein the first sacrificial material
has a first vertical axis and the work piece has a second vertical
axis, wherein the first vertical axis and the second vertical axis
form an angle, said angle being about zero.
14. A method for processing a work piece having a front end, a back
end, and a plurality of lateral sides, the method comprising:
providing a die, said die having an entrance channel with a
longitudinal axis and an exit channel, said entrance channel and
said exit channel being connected to one another; disposing a first
sacrificial material between said die and at least one lateral side
of the work piece while leaving said front end and said back end
substantially free from contact with said first sacrificial
material; disposing a second sacrificial material between said die
and at least one other lateral side of the work piece while leaving
said front end and said back end substantially free from contact
with said second sacrificial material; extruding said first
sacrificial material, said second sacrificial material and said
work piece through said die and through the exit channel.
15. The method of claim 14, wherein said first sacrificial material
is about the same size as the work piece.
16. The method of claim 14, wherein said second sacrificial
material is about the same size as the work piece.
17. The method of claim 14, wherein said second sacrificial
material and said first sacrificial material each have a flow
stress, said flow stress being less than another flow stress of the
work piece.
18. (canceled)
19. The method of claim 1, wherein all of said plurality of lateral
sides contact either said first sacrificial material and said
second sacrificial material.
20. The method of claim 14, further comprising the step of
repeatedly extruding said first sacrificial material and said
second sacrificial material with the work piece through said
die.
21. The method of claim 14, wherein the work piece is selected from
the group consisting of nickel, a nickel alloy, a nickel base
alloy, a nickel base alloy being strengthened by a precipitate,
nickel base alloy being strengthened by a gamma prime precipitate,
a nickel based super alloy, a co-base super alloy, an oxide
dispersion strengthened alloy, a multi-layered combination of
materials, an iron based alloy, and an aluminum based alloy, a
titanium, a titanium alloy, and any combination thereof.
22. The method of claim 14, wherein said first sacrificial material
is selected form the group consisting of graphite, carbon,
aluminum, an aluminum alloy, a copper, a copper alloy, and any
combination thereof, and wherein said second sacrificial material
is selected from the group consisting of aluminum, an aluminum
alloy, a copper, and a copper alloy.
23. An extrusion apparatus comprising: a die cavity forming an "L"
shaped extrusion channel; and a plurality of sacrificial materials
in said extrusion channel; wherein said plurality of sacrificial
materials contact a first lateral side and a second lateral side of
a work piece, wherein said work piece has a front side, and a rear
side; wherein said plurality of sacrificial materials impart a
shear deformation on said first and said second lateral sides of
the work piece upon extrusion through said extrusion channel;
wherein said plurality of sacrificial materials leave said front
side and said rear side exposed; and wherein said plurality of
sacrificial materials have a flow stress required to cause a
plastic deformation, said flow stress being less than a second flow
stress of the work piece.
24. The method of claim 14, wherein said second sacrificial
material and said first sacrificial material each have a flow
stress, said flow stress being about the same as another flow
stress of the work piece.
25. The apparatus of claim 23, wherein said plurality of
sacrificial materials have a flow stress required to cause a
plastic deformation, said flow stress about the same as a second
flow stress of the work piece.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present disclosure is directed to a fabrication process
of a structural component. More particularly, the present
disclosure is related to a fabrication process for a structural
component to be used with high strength structural applications.
Even more particularly, the present disclosure relates to a
fabrication process for a structural component that results in a
component having a homogeneous nano/sub-micron grain structure.
[0003] 2. Description of the Related Art
[0004] High strength engineering components are known in the art.
Plastic deformation has been used in the art to structurally alter
and to enhance one or more physical properties of a work piece
component for different metallic materials. One such known method
entails using a die having a movable surface in a deformation
channel of the die. The movable surface moves with a work piece
material during a deformation process in the deformation channel.
The billets have selected desired characteristics resulting from
the deformation processing such as an improved strength and
ductility. However, construction using such billets is expensive,
due in part, because the billets or desired structural components
can be formed only by using a very complex and cumbersome die
structure. The complex die structure and components are expensive
to use and make. They require additional expenses not only to form
the die, but also to operate, and service the die for manufacturing
a number of structural components or billets.
[0005] Moreover, such known dies have a detrimental operation and
have die components that only minimize friction in one general
direction or on the face of the work piece material. Such dies
minimize friction in only a complementary location where a sliding
die component moves. Such a reduction in friction may only provide
a limited structural enhancement depending on the application. The
friction on another side of the work piece material is relatively
greater between the die component and the structural work piece
component. This results in non-homogenous sized grains in the
resulting structural component. This non-homogenous condition due
to the increased friction on the one side relates to poor
mechanical properties. This may lead to one or more unintended
detriments depending on the structural application.
[0006] Thus, a need exists to develop a fabrication method which
includes improved process steps that do not require an expensive
die or die components to conduct the plastic deformation process.
In addition, a need exists to develop a fabrication process that
provides a homogenous sub-micron grain size across the cross
section of the work piece component.
SUMMARY
[0007] According to a first aspect of the present disclosure, there
is provided a method for processing a work piece having a front
end, a back end, and a plurality of lateral sides. The method has
the steps of providing a die having an entrance channel with a
longitudinal axis and an exit channel. The entrance channel and the
exit channel are connected to one another. The method has the step
of placing the work piece in the entrance channel and disposing a
first sacrificial material between the die and at least one lateral
side of the work piece. The method also has the steps of extruding
the first sacrificial material and the work piece material through
the exit channel.
[0008] According to another aspect of the present disclosure, the
method has the front end and the back end exposed and substantially
free from contacting the first sacrificial material.
[0009] According to yet another aspect of the present disclosure,
the method has all of the plurality of lateral sides in contact
with the first sacrificial material.
[0010] According to still another aspect of the present disclosure,
the method has first sacrificial material and the work piece with
each being substantially orthogonal shaped members with a flat
mating surface.
[0011] According to still yet another aspect of the present
disclosure, the method has the work piece selected from the group
consisting of nickel, a nickel alloy, a nickel base alloy, a nickel
base alloy being strengthened by a precipitate, nickel base alloy
being strengthened by a gamma prime precipitate or a nickel based
super alloy, a co-base super alloy, an oxide dispersion
strengthened alloy, a multi-layered combination of materials, an
iron based alloy, and an aluminum based alloy, and titanium and
titanium alloys.
[0012] According to another aspect of the present disclosure, the
method has the first sacrificial material selected from the group
consisting of carbon, graphite, aluminum, an aluminum alloy,
copper, and a copper alloy.
[0013] According to still yet another aspect of the present
disclosure, the method has sub-micron sized grains formed in the
work piece. The grains are disposed in a substantially homogenous
fashion throughout a cross section of the work piece.
[0014] According to yet another aspect of the present disclosure,
the method has the first sacrificial material surrounding the work
piece in a manner to reduce friction between the work piece during
extrusion. The method also has the step of optionally repeating
extrusion of the first sacrificial material and the work piece
through the die.
[0015] According to another aspect of the present disclosure, the
method has the first sacrificial material with substantially the
same flow stress as the work piece.
[0016] According to another aspect of the present disclosure, the
method has the first sacrificial material and the die have a first
coefficient of friction at an interface therebetween. The first
coefficient of friction is different relative to a second
coefficient of friction being between a second interface between
the die and the work piece.
[0017] According to another aspect of the present disclosure, the
method has the sacrificial material and the work piece
substantially filling the entrance channel.
[0018] According to another aspect of the present disclosure, the
method has the first sacrificial material and the work piece
substantially filling the exit channel.
[0019] According to another aspect of the present disclosure, the
method has the first sacrificial material with a first vertical
axis and the work piece having a second vertical axis. The first
vertical axis and the second vertical axis form an angle. The angle
is about zero.
[0020] According to another aspect of the present disclosure, there
is provided a method for processing a work piece with a front end,
a back end, and a plurality of lateral sides. The method has the
step of providing a die with the die having an entrance channel and
a longitudinal axis and an exit channel. The entrance channel and
the exit channel are connected to one another, and the method also
has the step of placing the work piece in the entrance channel with
the step of disposing a first sacrificial material between the die
and at least one lateral side of the work piece. The method further
has the step of disposing a second sacrificial material between the
die and at least one other lateral side of the work piece with the
step of extruding the first sacrificial material, the second
sacrificial material and the work piece through the die and through
the exit channel.
[0021] According to another aspect of the present disclosure, the
method has the first sacrificial material about the same size as
the work piece.
[0022] According to another aspect of the present disclosure, the
method has the second sacrificial material about the same size as
the work piece.
[0023] According to still another aspect of the present disclosure,
the method has the second sacrificial material and the first
sacrificial material each with a flow stress. The flow stress is
less than the flow stress of the work piece.
[0024] According to another aspect of the present disclosure, the
method has the front end and the back end exposed and substantially
free from contact with the first sacrificial material and the
second sacrificial material.
[0025] According to another aspect of the present disclosure, the
method has all of the lateral sides contacting either the first
sacrificial material and the second sacrificial material.
[0026] According to another aspect of the present disclosure, the
method has the step of imparting a clamping force perpendicular to
the work piece to hold the work piece composite in the die.
[0027] According to another aspect of the present disclosure, the
method further comprises the step of repeatedly extruding the first
sacrificial material and the second sacrificial material with the
work piece through the die.
[0028] According to another aspect of the present disclosure, there
is provided an extrusion apparatus. The apparatus has a first "L"
shaped die cavity forming an "L" shaped extrusion channel and a
plurality of sacrificial materials in the extrusion channel. The
apparatus also has the plurality of sacrificial materials
contacting a first lateral side and a second lateral side of a work
piece. The work piece also has a front side, and a rear side. The
apparatus further has the plurality of sacrificial materials
imparting a shear deformation on the first and the second lateral
sides of the work piece material upon extrusion through the
extrusion channel and the plurality of sacrificial materials leave
the front side and the rear side exposed.
BRIEF DESCRIPTION OF THE FIGURES
[0029] Various embodiments will be described herein below with
reference to the drawings wherein:
[0030] FIG. 1 is a flow chart of the fabrication process according
to the present disclosure;
[0031] FIG. 2 is a schematic diagram of a die having a first
extrusion channel and a second extrusion channel according to the
present fabrication process;
[0032] FIG. 3 is a schematic diagram of a work piece material
placed between a first sacrificial material and a second
sacrificial material;
[0033] FIG. 4 is another schematic view of the die of FIG. 2 with
the work piece material of FIG. 3 in the die and between the first
sacrificial material and the second sacrificial material;
[0034] FIG. 5 is a lateral side view of a first sacrificial
material made from aluminum and the work piece material made from
nickel after being extruded;
[0035] FIG. 6 is a view of the nano/sub-micron grains of the work
piece material at 50 nm;
[0036] FIG. 7 is another view of the nano/sub-micron grains of the
work piece material at 50 nm;
[0037] FIG. 8 is a view of the nano/sub-micron grains of the work
piece material at 110 nm; and
[0038] FIG. 9 is another view of the nano/sub-micron grains of the
work piece material at about 122 nm.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0039] Reference should be made to the drawings where like
reference numerals refer to similar elements throughout the various
figures. The fabrication process of the present disclosure controls
a microstructure of a work piece material resulting from a
deformation of the work piece material. The fabrication process
uses a first sacrificial material and, in some embodiments, a
second sacrificial material, to reduce friction between a die and
the work piece, and thus form a homogenous nano/sub micron sized
grains in the work piece material or work piece.
[0040] Referring now to FIG. 1, there is shown a process flow chart
of the fabrication method 10 of the present disclosure. The method
10 has the first step 12 of arranging the die. Thereafter, the
method proceeds to step 14. At step 14, the method has the step of
providing a work piece in the die. The work piece is defined as the
material that will undergo the plastic deformation in order to
result in a controlled microstructure. Thereafter, the method
proceeds to step 16. At step 16, a first sacrificial material is
prepared. The first sacrificial material has dimensions that are
complementary to the dimensions of the work piece material. The
first sacrificial material moves with the work piece material
during a shear process and thus reduces friction and contact
between the work piece material and the die. Thereafter, the method
proceeds to step 18.
[0041] At step 18, for those embodiments employing a second
sacrificial material, the second sacrificial material is prepared.
The second sacrificial material has dimensions that are also
complementary to the dimensions of the work piece material and the
first sacrificial material. Likewise, the second sacrificial
material moves with the work piece material during the shear
process and thus reduces friction between the work piece material
and the die. The second sacrificial material is placed on an
opposite side of the work piece material so that the first
sacrificial material and the second sacrificial material are
opposite one another with the work piece material between both the
first sacrificial material and the second sacrificial material to
form a composite or sandwich. Thereafter, the method proceeds to
step 20.
[0042] At step 20, the first sacrificial material and the second
sacrificial material (if used) opposite the first sacrificial
material with the work piece material disposed therebetween are all
placed in an entrance channel of the die. Thereafter, the method
proceeds to step 22. At step 22, a suitable force is applied to the
combined first sacrificial material/work piece material and second
sacrificial material to extrude the composite billet through the
die. Thereafter, the method proceeds to step 24. At step 24, the
extrusion step may be optionally repeated. One should appreciate
the method may advantageously be conducted with a single pass
through the die, and the method is not limited to any multiple
passes through the die. Notwithstanding, the extrusion step may be
optionally repeated with a 180 degree rotation of the combined
first sacrificial material/work piece material and second
sacrificial material. Thereafter, the method proceeds to step 26.
At step 26, the resulting work piece material having homogenous and
uniform sub-micron grains is removed from the first and the second
sacrificial materials and is ready for a final finishing operation
to make the work piece material ready for the relevant high
strength application. One such application may be an airfoil or a
turbine blade. Various finished product configurations are
possible.
[0043] Referring to FIG. 2, there is shown a schematic diagram of
one embodiment of the presently disclosed system 28 with a die 30
for forming a number of sub-micron sized grains in the work piece
material. "Submicron" sized or "nano sized" grains means that the
resulting deformation process forms grains in a range of size that
includes below a millionth of a meter. This process is called equal
channel angular extrusion. By decreasing a grain size of the work
piece material, an increase in strength of the material will
result. A microstructure with nano or sub-micron sized grains
results from the deformation processing. The nano sized grains and
the homogeneous arrangement of the nano sized grains enhance one or
more mechanical properties of the work piece material resulting
from the deformation. The resulting work piece material having
increased strength can then be used in any number of applications,
such a turbine application, a turbine blade application, a
compressor application, a compressor blade application, a nuclear
application, a combustor application, a fan compressor application,
an airfoil application, an air inlet application, or an air or gas
exhaust application, a transportation or aerospace application, a
rotary rotational movement application, or any other number of
applications that require a structural component with a controlled
microstructure and high strength or improved ductility.
[0044] The die 30 has a first die component 32 and a second die
component 34 with a die cavity 36 disposed between the first die
component 32 and the second die component 34. The first die
component 32 and the second die component 34 each are made from a
tool steel, or another suitable high strength suitable material, or
alloy. The die 30 is made from a suitable material that will
maintain integrity during an extrusion process. The first die
component 32 and the second die component 34 are form substantially
an "L" shaped die cavity 36.
[0045] The die 30 also has other assemblies in order to clamp and
connect the first die component 32 to the second die component 34
with another material therein disposed therebetween. The die 30
further has an entrance channel 38 and an opposite exit channel 40.
Each of the entrance channel 38 and the exit channel 40 are
generally orthogonal shaped and communicate with the die cavity 36.
In another embodiment, the entrance channel 38 and the exit channel
40 may have different shapes or configurations relative to one
another such as a circular configuration.
[0046] Referring now to FIG. 3, the system 28 further has a first
sacrificial material 42 and a second sacrificial material 44. The
first and the second sacrificial materials 42, 44 are generally
orthogonal or rectangular members each made of the same or a
different material. In this embodiment, the first and the second
sacrificial materials 42, 44 each have a substantially flat outer
surface. The term "sacrificial" means that the material of this
element of the present disclosure is intended not to form any of
the finished final structurally enhanced products, and is intended
to be discarded.
[0047] The system 28 further has a work piece 46. The work piece 46
is a member in which the nano/sub micron sized grains are to be
formed, and that is to be used as the high strength component as
discussed previously. The work piece 46 is generally an orthogonal
shaped or a rectangular member. In another embodiment, the work
piece 46 may have any desired shape as long as the sacrificial
materials 42, 44 have the complementary shape to accommodate the
work piece 46. In this embodiment, the work piece 46 has a
substantially flat outer surface. The work piece 46 may be nickel,
a nickel alloy, a nickel base alloy, a nickel base alloy being
strengthened by a precipitate, nickel base alloy being strengthened
by a gamma prime precipitate or a nickel based super alloy, a
co-base super alloy, an oxide dispersion strengthened alloy, a
multi-layered combination of materials or a composite, an iron
based alloy, and an aluminum based alloy, and titanium and titanium
alloys or a suitable combination of materials. The sacrificial
materials have a flow stress less than or equal to the flow stress
of the work piece 46. The flow stress is the stress required to
cause a plastic deformation in metallic materials. If the flow
stress of the sacrificial materials 42, 44 is low, the overall
applied force required to deform the system is lowered. This places
less demanding requirements on the press used for extrusion. Pure
aluminum, as one non-limiting exemplary example, has a range of
flow stress from 2 to 70 Megapascals (hereinafter "MPa") depending
on temperature, strain rate and strain. Work pieces 46 will usually
be relatively much higher or as much as 1,000 Mpa.
[0048] The first sacrificial material 42 and the second sacrificial
material 44 are both disposed to surround the work piece 46 so as
to move with the work piece 46 during an extrusion process through
the die cavity 36 of FIG. 2. The first sacrificial material 42 is
disposed on a first lateral side 48 of the work piece 46 and the
second sacrificial material 44 is disposed on an opposite or second
lateral side 50. The first sacrificial material 42 is disposed
substantially parallel to the work piece 46 on the first lateral
side 48 so an angle therebetween is about zero. The second
sacrificial material 44 is also likewise disposed substantially
parallel to the work piece 46 on the opposite side 50 of the first
sacrificial material 42 so an angle therebetween is about zero.
Each of the first sacrificial material 42 and the second
sacrificial material 44 has a similar and complementary
configuration relative to one another. Additionally, each, in
another embodiment, may have the same material having the same size
and shape. In one embodiment, each is a substantially rectangular
shaped member. The first sacrificial material 42 may be aluminum,
an aluminum alloy, a copper, a copper alloy, a combination thereof,
or any material with a relatively low flow stress. Likewise the
second sacrificial material 44 may be the same or different than
the first sacrificial material 42 and may be aluminum, an aluminum
alloy, a copper, a copper alloy, a combination thereof, or any
material with a low flow stress. The first and the second
sacrificial materials 42, 44 instead each have flow properties or
characteristics that allow the first and the second sacrificial
materials 42, 44 to flow with the work piece 46 in a manner such
that the work piece 46 experiences less friction between the work
piece 46 and the die cavity 36 during extrusion. The first and the
second sacrificial materials 42, 44 are intended to prevent the
work piece 46 from contacting some of the inner surfaces of the die
30. This prevents friction forces arising from any contact with the
die 30 thereby potentially causing a non-homogenous grain size in
the work piece 46 during the severe plastic deformation in the die
30 during extrusion. The first and the second sacrificial materials
42, 44 with low flow stress, also serve the purpose of reducing
overall loads to effect extrusion. Moreover, the first and the
second sacrificial materials 42, 44 also enable extrusion of thin
sheets of work pieces 46.
[0049] Referring now to FIG. 3, there is shown a perspective view
of the first sacrificial material 42, and the second sacrificial
material 44 with the work piece 46 placed therebetween. As shown,
each of the first sacrificial material 42 and the second
sacrificial material 44 with the work piece 46 forms an unconnected
composite structure collectively indicated by reference numeral 52.
Referring now to FIG. 4, the composite 52 or sandwich is placed in
the die 30. One aspect of the present disclosure is that the first
sacrificial material 42 has a first vertical axis 54 and the work
piece 46 also has a second vertical axis 56. The angle between the
first vertical axis 54 and the second vertical 56 axis is zero when
the first sacrificial material 42 is placed adjacent to the work
piece 46 as shown in FIG. 3.
[0050] Likewise, the second sacrificial material 44 has a third
vertical axis 58. The angle between the third vertical axis 58 and
the second vertical axis 56 of the work piece 46 is also zero when
the second sacrificial material 44 is placed adjacent to the work
piece 46 as shown in FIG. 3. A suitable lubricant is then applied
to one or more inner surfaces of the die cavity 36 as shown in FIG.
4. Various lubricants or lubricating configurations are possible
and are within the scope of the present disclosure. The composite
52 then undergoes a severe plastic deformation by an Equal Channel
Angular Extrusion using the die 30, where the composite 52 is
extruded from the entrance channel 38 through the exit channel 40
by Force F as illustrated by the reference arrow. The Equal Channel
Angular Extrusion operation results in the work piece 46 during the
extrusion undergoing an intense shear deformation by passage
through the die cavity 36. This leads to a refinement of the
microstructure of the work piece 46 of the composite 52 or
sandwich. The extrusion process can be performed using a suitable
hydraulic pressing apparatus introduced into the entrance channel
36 of the die 30. Various extrusion apparatus configurations or
pressing apparatuses such as ECA pressing are possible and all are
within the scope of the present disclosure.
[0051] Referring now to FIG. 5 there is shown a perspective view of
an aluminum first sacrificial material 60 and a work piece 62 using
an aluminum second sacrificial material and a nickel work piece. As
can be seen by the figure, the nickel work piece has undulations 66
on a first lateral side 64 that are indicative of a shearing
process. The undulations 66 indicate that the first lateral side 64
saw substantially no friction from the die cavity 36 or die
component and a homogenous amount of undulations are present. The
undulations 66 are present along substantially the entire lateral
side 64 and are only absent only a slight proximal distance from a
top surface 68 and a bottom surface 70. This indicates that the
friction from the first die component 32 is confined to the top and
the bottom surfaces 68, 70. Referring now to FIGS. 6 and 7, there
is shown a microscopic view of the nickel work piece 62 of FIG. 5.
Diffraction patterns corresponding to FIG. 6 are shown in FIGS. 8
and 9. Straight arrows connect the diffraction patterns to the
areas from where they were obtained. The diffraction pattern from
the central dark region in FIG. 6 corresponds to a zone axis close
to about 110. The diffraction pattern from the area surrounding the
central dark area region in FIG. 6 corresponds to a zone axis close
to about 122. These two zone axes are at an angle of about forty
five degrees. Hence, the central dark area in FIG. 6 is definitely
a nano-grain. The nano-grain has a dimension of about 60
nanometers.
[0052] It should be understood that the foregoing description is
only illustrative of the present disclosure. Various alternatives
and modifications can be devised by those skilled in the art
without departing from the disclosure. Accordingly, the present
disclosure is intended to embrace all such alternatives,
modifications and variances. The embodiments described with
reference to the attached drawing figures are presented only to
demonstrate certain examples of the disclosure. Other elements,
steps, methods and techniques that are insubstantially different
from those described above and/or in the appended claims are also
intended to be within the scope of the disclosure.
* * * * *