U.S. patent application number 10/039811 was filed with the patent office on 2002-09-26 for metal consolidation process applicable to functionally gradient material (fgm) compositions of tantalum and other materials.
Invention is credited to Dilmore, Morris F., Fleming, Marc S., Meeks, Henry S. III.
Application Number | 20020136658 10/039811 |
Document ID | / |
Family ID | 27069695 |
Filed Date | 2002-09-26 |
United States Patent
Application |
20020136658 |
Kind Code |
A1 |
Dilmore, Morris F. ; et
al. |
September 26, 2002 |
Metal consolidation process applicable to functionally gradient
material (FGM) compositions of tantalum and other materials
Abstract
The method of consolidating a body in any of initially powdered,
sintered, fibrous, sponge, or other form capable of compaction,
that includes providing flowable pressure transmission particles
having carbonaceous and ceramic composition or compositions;
heating particles to elevated temperature; locating the heated
particles in a bed; positioning the body at the bed, to receive
pressure transmission; effecting pressurization of the bed to cause
pressure transmission via the particles to the body, thereby to
compact and consolidate the body into desired shape, increasing its
density, the body consisting essentially of one or more metals
selected from the following group: tungsten, rhenium, uranium,
tantalum, platinum, copper, gold, hafnium, molybdenum, titanium,
zirconium, aluminum, the consolidated body having, along a body
dimension, one of the following characteristics: decreasing
strength, increasing strength, or decreasing ductility (strain
hardening) and increasing ductility (strain hardening).
Inventors: |
Dilmore, Morris F.; (Baker,
FL) ; Meeks, Henry S. III; (Roseville, CA) ;
Fleming, Marc S.; (Rancho Cordova, CA) |
Correspondence
Address: |
William W. Haefliger
Suite 512
201 So. Lake Ave.
Pasadena
CA
91101
US
|
Family ID: |
27069695 |
Appl. No.: |
10/039811 |
Filed: |
January 8, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10039811 |
Jan 8, 2002 |
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09592974 |
Jun 12, 2000 |
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09592974 |
Jun 12, 2000 |
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09551248 |
Apr 18, 2000 |
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6355209 |
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Current U.S.
Class: |
419/6 ;
75/228 |
Current CPC
Class: |
B22F 2998/00 20130101;
B22F 2998/00 20130101; B22F 3/156 20130101; B22F 3/156 20130101;
B22F 2207/01 20130101; B22F 2998/00 20130101; B22F 3/15
20130101 |
Class at
Publication: |
419/6 ;
75/228 |
International
Class: |
B22F 003/04 |
Claims
I claim:
1. In the method of consolidating a body in any of initially
powdered, sintered, fibrous, sponge, or other form capable of
compaction, that includes the steps: a) providing flowable pressure
transmission particles having carbonaceous and ceramic composition
or compositions, b) heating said particles to elevated temperature,
c) locating said heated particles in a bed, d) positioning said
body at said bed, to receive pressure transmission, e) effecting
pressurization of said bed to cause pressure transmission via said
particles to said body, thereby to compact and consolidate the body
into desired shape, increasing its density; f) the body consisting
essentially of one or more metals selected from the following
group: tungsten, rhenium, uranium, tantalum, platinum, copper,
gold, hafnium, molybdenum, titanium, zirconium and aluminum; g)
said consolidated body having, along a body dimension, one of the
following characteristics: i) decreasing strength ii) increasing
ductility iii) decreasing strength, and increasing ductility.
2. The method of claim 1 wherein the body has varying metallic
composition along said dimension.
3. The method of claim 1 wherein said varying metallic composition
is characterized by a series of zones, the metal of each zone
having a characteristic composition which differs from that of an
adjacent zone or zones.
4. The method of claim 3 wherein the metals in at least two
successive zones consist substantially of tantalum, and tantalum
consolidated with a metal or metals selected from the group
tungsten, rhenium, uranium, tantalum, platinum, copper, gold,
hafnium, molybdenum, titanium, zirconium and aluminum.
5. The method of claim 1 wherein said body consists of powders of
metals that have been initially combined and compressed into body
form, at pressure exceeding 20,000 pounds per square inch, prior to
said step e) pressurization.
6. The method of claim 5 wherein at least part of said body has one
of the following forms: i) cone ii) lens iii) cylinder iv) cylinder
and cone combination v) cylinder and lens combination.
7. The method of claim 5 including preheating said body to
temperature in excess of 900.degree. C., subsequent to said initial
combining and compressing and prior to said pressurization.
8. The method of claim 5 including effecting said initial combining
and compressing at ambient temperature.
9. The method of claim 5 including providing an elastomeric
container, positioning said powders in said container, and
effecting said initial compressing by compressing said
container.
10. The method of claim 9 including evacuating gases from said
container, prior to said initial compressing thereof.
11. The method of claim 10 including sealing of said container
after evacuating gases therefrom.
12. The method of claim 11 wherein said initial compressing is
effected to compress the body to about 60% of body theoretical
density.
13. The method of claim 1 wherein said pressurization is effected
to form the body into generally conical shape.
14. The method of claim 1 including effecting said initial
compressing to form the body into generally cylindrical shape, with
taper at one end.
15. The method of claim 14 wherein said pressurization is carried
out to reduce the body size while maintaining body generally
cylindrical shape with taper at one end.
16. The method of claim 5 wherein the powders at one zone of the
body consist essentially of tantalum particles coated with
substance or substances selected from the group that include
tungsten, rhenium, uranium, platinum, copper, gold, hafnium,
molybdenum, titanium, zirconium and aluminum.
17. The method of claim 16 wherein the weight percent of said
substance or substances is about 16% of the overall weight of the
total powder.
18. The consolidated body produced by the method of claim 1.
19. The method of claim 1 wherein said particles are generally
spheroidal and consist of graphite, and/or graphite and ceramic
composite.
20. The method of claim 1 wherein said body in said bed, prior to
said step e) is at a temperature between about 200.degree. C. and
1,800.degree. C.
21. The method of claim 1 wherein said body is positioned in said
bed to be surrounded by said particulate, the bed consisting
substantially entirely of particles in the form of graphite and/or
graphite/ceramic beads.
22. The method of claim 15 wherein said bed contains sufficient of
said flowable particles as to remain essentially free of
agglomeration during said (e) step.
23. The method of claim 1 wherein said bed consists essentially of
one of the following particulates: i) graphite ii) ceramic iii)
graphite and ceramic.
24. The method of claim 23 wherein the particle mesh size is
between 50 and 240.
25. The method of consolidating metal powder to form an object,
that includes: a) pressing said powder into a preform, and
preheating the preform to elevated temperature, b) providing
flowable pressure transmitting particles and heating said
particles, and providing a bed of said flowable and heated pressure
transmitting particles, c) positioning the preform in such relation
to the bed that the particles substantially encompass the preform,
d) and pressurizing said bed to compress said particles and cause
pressure transmission via the particles to the preform, thereby to
consolidate the preform into a desired object shape, e) the preform
consisting of one or more metals selected from the following group:
tungsten, rhenium, uranium, tantalum, platinum, copper, gold,
hafnium, molybdenum, titanium, zirconium and aluminum.
26. The method of claim 25 wherein the powder at one zone of the
body consists of tantalum particles coated with substances selected
from the group that includes tungsten, rhenium, uranium, platinum,
copper, gold, hafnium, molybdenum, titanium, zirconium and
aluminum.
27. The method of claim 26 wherein the weight percent of said
substances is about 16% of the overall weight of the total
powder.
28. The method of claim 25 wherein said pressurization is effected
at levels greater than about 20,000 psi for a time interval of less
than about 30 seconds.
29. The method that includes a) providing particles to be used in
pressure consolidation of a powdered preform; b) heating said
particles, c) and pressurizing the heated particles to effect said
consolidation, d) said preform consisting essentially of metallic
particles selected from the following group: tungsten, rhenium,
uranium, tantalum, platinum, copper, gold, hafnium, molybdenum,
titanium, zirconium and aluminum.
30. The method of claim 29 wherein the particles include tantalum
which constitutes more than 50% of the overall weight of the
preform.
31. The method of claim 29 wherein the preform initial powder
consists of tantalum particles on which the metallic particles are
coated.
32. A metallic body which has been compressed and consolidated from
an initial powder metal form to a highly densified form, the body
consisting of at least two metals, the proportions of which vary
along a body dimension, one of said metals being tantalum.
33. The body of claim 32 wherein the body consists of at least four
metals.
34. The body of claim 33 wherein said metals are selected from the
group that includes tungsten, rhenium, uranium, tantalum, platinum,
copper, gold, hafnium, molybdenum, titanium, zirconium and
aluminum.
35. The body of claim 32 wherein the body is elongated and has a
tapered nose portion, there being a second body portion along said
dimension, the body consisting of at least two metals, M.sub.1 and
M.sub.2, the proportions of M.sub.1 and M.sub.2 in said body nose
portion and second body portion being different.
36. The body of claim 35 wherein the metal M.sub.1 is tantalum, the
proportion of tantalum in said nose portion being greater than the
proportion of tantalum in said second body portion.
37. The body of claim 36 wherein the body has third and fourth body
portions along said dimension, the proportion of tantalum in said
second body portion exceeding the proportion of tantalum in said
third body portion, and the proportion of tantalum in said third
body portion exceeding the proportion of tantalum in said fourth
body portion.
38. The body of claim 32 wherein the body has first and second
ends, the consolidated metal at the first end having higher density
than the metal at the second end.
39. The body of claim 38 wherein the metal at the first end
consists primarily of tantalum, and the metal at the second end
consists primarily of M.sub.1, M.sub.2, or M.sub.x.
40. A pressure consolidated powdered metal product wherein the
powdered metal is distributed in successive layers, each layer
having a different weight percentage of consolidated powdered
metals, at least one of the powdered metals being tantalum.
41. The body of claim 32 which has decreasing strength or ductility
in each of two body dimensions.
42. The body of claim 41 wherein said two dimensions are length and
thickness.
43. The body of claim 41 wherein said two dimensions are
longitudinal and lateral.
44. The body of claim 41 wherein said body tapers toward a top
zone, the body ductility and/or strength being greatest at said top
zone.
45. The body of claim 41 wherein said body comprises a conical
shell.
46. The body of claim 41 which has a cylindrical section and a
tapered section at one end of the cylindrical section.
47. The method of claim 32 wherein the consolidated tantalum has
<111> texture of less than about 2.8.times. random.
Description
[0001] This application is a continuation-in-part of prior U.S.
patent application Ser. No. 09/551,248, filed Apr. 18, 2000,
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to the field of
consolidating hard metallic bodies, and also to rapid and efficient
and heating and handling of granular media employed in such
consolidation, as well as rapid and efficient heating and handling
of preform powdered metal or metal bodies to be consolidated, where
such bodies consist essentially of functionally gradient materials,
designated herein as FGM. Such materials when consolidated exhibit
along a body dimension or dimensions decreased or varying strength
or ductility (strain hardening).
[0003] The technique of employing carbonaceous particulate or grain
at high temperature as pressure transmitting media for producing
high density metallic objects is discussed at length in U.S. Pat.
Nos. 4,140,711, 4,933,140 and 4,539,175, the disclosures of which
are incorporated herein, by reference.
[0004] The present invention provides improvements in such
techniques, and particularly improvement leading to consolidation
of bodies consisting essentially of functionally gradient material
(FGM) compositions. One example is tantalum or tantalum together
with other metals. Such metals, one or more of which may be
consolidated with tantalum, include tungsten, copper, hafnium,
rhenium, platinum, gold, molybdenum, uranium, titanium, zirconium
and aluminum.
SUMMARY OF THE INVENTION
[0005] It is a major object of the invention to provide for
consolidation of metallic powder consisting of selected metals as
referred to, and as may be employed in target penetration,
drilling, and related impact activities. Such selected metals
typically are distributed as FGMs, as referred to.
[0006] It is another object of the invention to provide rapid and
efficient heating of carbonaceous and/or ceramic particles used as
pressure transmitting media, and also transfer of heat generated in
the particles to the work, i.e. the hard metal preform to be
consolidated. Basic steps of the method of consolidating the
preform metallic body in any of initially powdered, sintered,
fibrous, sponge, or other form capable of compaction, or
densification (to reduce porosity) then include the steps:
[0007] a) providing flowable particles having carbonaceous and
ceramic composition or compositions,
[0008] b) heating the particles to elevated temperature,
[0009] c) locating the heated particles in a bed,
[0010] d) positioning the preform body at the bed, to receive
pressure transmission,
[0011] e) effecting pressurization of said bed to cause pressure
transmission via said particles to the body, thereby to compact the
body into desired shape, as for example cylindrical shape,
increasing its density, and
[0012] f) the body consisting essentially of one or more metals
selected from the following group: tungsten, rhenium, uranium,
tantalum, platinum, copper, gold, hafnium, molybdenum, titanium,
zirconium and aluminum,
[0013] g) the consolidated body having, along a body dimension, one
of the following characteristics:
[0014] i) decreasing strength
[0015] ii) increasing ductility
[0016] iii) decreasing strength, and increasing ductility.
[0017] Another object is to achieve rapid or almost instantaneous
densification of a composite metal alloy system, the resultant
material being fine grained, isotropic, and maintaining original
metastable microstructures.
[0018] A further object is to produce a consolidated functionally
gradient material (FGM) for use as a shaped, heavy metal penetrator
EFP (explosively formed penetrator) or SCL (shaped charge lines).
One highly advantageous and particular FGM material powder system
is comprised of a tantalum and other heavy metal powdered alloy
outer section, and transitioning to a different density based
powder. It may include an intermediate layer of metal matrix
composite of the heavy metal alloy, and lower density powder, and a
monolithic lower density base section. The powdered material system
for process A may typically employ tantalum particles coated with a
pre-alloyed binder composition but other elementally blended, mixed
or otherwise combined particles are applicable. The total binder
may typically consist of elemental metals selected from the group
tungsten, copper, tantalum, hafnium, rhenium, platinum, gold,
molybdenum, and uranium hereinafter referred to as HMG, of
approximately 16 weight percent of the total composition; but other
compositions may be employed. The powdered material system for a
process B may typically employ transition layers of one metal to
the next with the build-up based on requirements.
[0019] The ability to fabricate a functionally gradient heavy metal
penetrator in one single forging operation has several advantages.
The first is the ability to design and engineer a penetrator with
specific and predictable dynamic performance criteria. The second
advantage is that of reduced manufacturing costs directly related
to fewer hot forging steps. Additional cost reductions are realized
in the area of raw material usage by eliminating forging trim and
scrappage resulting from the use of a powder metallurgy, near net
shape forging preform.
[0020] By the use of the methodology of the present invention,
substantially improved structural articles of manufacture can be
made having minimal distortion, as particularly enabled by the use
of carbonaceous, or ceramic, or carbonaceous/ceramic particulate in
flowable form.
[0021] An additional object includes provision of a method for
consolidating hard metal and/or ceramic powder, and/or composite
material with or without polymeric powder, to form an object, that
includes
[0022] a) pressing the FGM into a preform, and preheating the
preform to elevated temperature,
[0023] b) providing flowable pressure transmitting particles and
heating said particles, and providing a bed of said flowable and
heated pressure transmitting particles,
[0024] c) positioning the FGM preform in such relation to the bed
that the particles substantially encompass the preform,
[0025] d) and pressurizing the bed to compress said particles and
cause pressure transmission via the particles to the preform,
thereby to consolidate the preform into a desired object shape,
having final density.
[0026] The preform typically consists of tantalum complex with
metals selected from the HGM group as referred to.
[0027] An additional object is to provide a body to be consolidated
having varying metallic composition along a body dimension. That
varying composition may be characterized by a series of zones,
extending either axially or radially for example along the
article's axis, each zone having a characteristic composition which
differs from that of an adjacent zone or zones. The metal in
successive zones may consist of at least consolidated tantalum, and
tantalum consolidated together with one or more metals from the HGM
group, and also steel, but in varying proportions in successive
zones. For a projectile having great penetration capability, a
tapered nose zone may consist primarily of tantalum, and successive
zones to the rear may contain less and less tantalum and more and
more steel.
[0028] For a three metal body, the metals being M.sub.1, M.sub.2
and M.sub.3, the weights W.sub.1, W.sub.2 and W.sub.3 per unit
volume of the respective metals M.sub.1, M.sub.2 and M.sub.3 are
related and selected, to be as follows:
W.sub.1>W.sub.2>W.sub.3
[0029] Other objects are to provide consolidated bodies such as
tapered shells, and/or cylindrical and tapered bodies, made by the
method of the invention, and having functional gradient properties
in two dimensions.
[0030] The novel features which are believed to be characteristic
of this invention, both as to its organization and method of
operation, together with further objectives and advantages thereof,
will be better understood from the following description considered
in connection with the accompanying drawings in which a presently
preferred embodiment of the invention is illustrated by way of
example. It is to be expressly understood, however, that the
drawings are for the purposes of illustration and description only
and are not intended as a definition of the limits of the
invention.
DRAWING DESCRIPTION
[0031] FIG. 1 is a flow diagram showing method steps of the present
invention;
[0032] FIG. 2 is a cut-away elevation showing the A consolidation
step of the present invention;
[0033] FIG. 3 is a vertical section showing preform pressurization,
prior to consolidation;
[0034] FIG. 4 is a view like FIG. 3, showing a modified
preform;
[0035] FIG. 5 is a view of a consolidated preform;
[0036] FIG. 6 shows a tantalum particle with layers of Z.sub.1,
Z.sub.2, and Z.sub.3 as found in a matrix;
[0037] FIG. 7 is a section taken through multiple layers of
different metals;
[0038] FIGS. 8a and 8b are side and bottom views of a consolidated
shaped charge liner (SCL) formed by the method of the invention;
and
[0039] FIGS. 9a and 9b are side and bottom views of a consolidated
explosively formed penetration (EFP) formed by the method of the
invention.
DETAILED DESCRIPTION
[0040] Referring first to FIG. 1, there is shown a flow diagram
illustrating method steps of the present invention. As can be seen
from numeral 10, initially a metal, metal and ceramic, or ceramic
article of manufacture or preform is made, for example, in the
shape of a penetrator or other body or impact tool such as a drill
or other product. One preferred embodiment contemplates the use of
a metal preform made of powdered tantalum, partially coated with
one or more HGM particles, then mechanically blended with a low
alloy steel powder. Preferably, tantalum constitutes more than 50%
of the overall weight of the preform. Other metallic or ceramic
particles or coatings may also be included. See for example FIG. 6
showing tantalum particles 100 coated with or surrounded by metals
Z.sub.1, Z.sub.2, and Z.sub.3, in a preform. A preform typically is
about 60 to 85 percent of theoretical density after the powder has
been made and compacted into a preformed shape, and it may
typically subsequently be sintered (see step 12 in FIG. 1) in order
to increase the strength. In the preferred embodiment, the preform
in billet form is subjected to cold or ambient temperature
isostatic compaction at about 60,000 pounds per square inch,
preferably within an evacuated and sealed elastomeric (rubber)
container. See for example FIG. 3 showing evacuated, sealed
elastomeric container 110, with the preform 111 located therein,
and shaped in the form of a cylinder. FIG. 5 is like FIG. 3, but
shows the preform 112 shaped in the form of a cylinder and having a
tapered end 112a, for penetration of hard targets. Fluid pressure
is supplied at 113 to the interior 114 of a metal vessel 115 within
which the tantalum, and other powdered metal (M.sub.1, M.sub.2,
etc.) preform, and its elastomeric container are located, to
pressurize the container and compact the powder preform. Once the
billet preform has been compacted to about 60% of theoretical
density, it is heated in a protective or reducing atmosphere, such
as Argon or hydrogen, to above 900.degree. C., in preparation for
consolidation. See step 14 in FIG. 1. Alternative steps include
step 12 sintering in FIG. 1, and re-heating at 14.
[0041] The consolidation process, illustrated at 16 in FIG. 1,
takes place after the hot preform (removed from 110 and 115) has
been placed, as for example in a bed of heated carbonaceous or
carbonaceous/ceramic particles as hereinbelow discussed in greater
detail. Consolidation takes place by subjecting the embedded
preform to elevated temperature and high pressure. In a preferred
embodiment, temperatures in the range of about 1,600.degree. F. and
uniaxial pressures of about 5 to 100 and higher TSI are used, for
compaction. The preform has now been densified and can be
separated, as noted at 18 in FIG. 1, whereby the carbonaceous
particles separate readily from the preform and can be recycled as
indicated at 19. If necessary, any particles adhering to the
preform can be removed and the final product can be further
finished, as for example machined.
[0042] Final product dimensional stability, to a high and desirable
degree, is obtained when the particle (grain) bed primarily (and
preferably substantially completely) consists of flowable
carbonaceous and/or ceramic particles. For best results, such
carbonaceous particles are resiliently compressible graphite beads,
and they have outward projecting nodules on and spaced part on
their generally spheroidally shaped outer surfaces, as well as
surface fissures. See for example U.S. Pat. No. 4,640,711. Their
preferred size is between 50 and 240 mesh. Useful granules are
further identified as desulphurized petroleum coke. Such carbon or
graphite particles have the following additional advantages in the
process:
[0043] 1. They form easily around corners and edges, to distribute
applied pressure essentially uniformly to and over the body being
compacted. The particles suffer very minimal fracture, under
compaction pressure.
[0044] 2. The particles are not abrasive, therefore reduced scoring
and wear of the die is achieved.
[0045] 3. They are elastically deformable, i.e. resiliently
compressible under pressure and at elevated temperature, the
particles being stable and usable up to 4,000.degree. F.; it is
found that the granules, accordingly, tend to separate easily from
(i.e. do not adhere to) the body surface when the body is removed
from the bed following compaction.
[0046] 4. The granules do not agglomerate, i.e. cling to one
another, as a result of the body compaction process. Accordingly,
the particles are readily recycled, for reuse, as at 19 in FIG.
1.
[0047] 5. The graphite particles become rapidly heated in response
to passage of electrical current or microwaves therethrough. The
particles are stable and usable at elevated temperatures up to
4,000.degree. F. Even though graphite oxidizes in air at
temperatures over 800.degree. F. Short exposures as during heatup
and cooldown, do not substantially harm the graphite particles.
[0048] Referring now to FIG. 2, the consolidation step is more
completely illustrated. In the preferred embodiment, the preform 20
(as for example preform 111 in FIG. 3 or preform 111a in FIG. 4)
has been completely embedded in a bed of carbonaceous particles 22
as described, and which in turn have been placed in a contained
zone 24a as in consolidation die 24. Press bed 26 forms a bottom
platen, while hydraulic press ram 28 defines a top and is used to
press down onto the particles 22 which distributes the applied
pressure non-isostatically (30% deformation (compression) axially
-10% deformation (tensile) radially) to the preform 20. The preform
is at a temperature between 200.degree. C. and 1,800.degree. C.,
prior to compaction. The embedded metal powder preform 20 is
rapidly compressed under high uniaxial pressure by the action of
ram 28 in die 24, the grain having been heated to between
400.degree. C. and 4,000.degree. F. Pressurization is typically
effected at levels greater than about 20,000 psi for a time
interval of less than about 30 seconds. Particles may be located
within a sub-bed in a deformable container, in bed 22.
[0049] Referring again to FIG. 2, a heating furnace 50 is shown,
incorporating a fluidized bed of grain particles, to be supplied at
51 to die 24. Such PTM can be a carbonaceous and ceramic composite
of varying composition ranging from 5 to 95 percent, by volume, of
ceramic particles, the balance being carbonaceous particles. Usable
ceramics include: aluminum oxide, boron carbide or nitride, and
other hard ceramic materials. The heater may comprise an electrical
resistance heater, or a microwave heater, for example.
[0050] FIG. 4 shows a preform 111a, similar to that at 111 in FIG.
3; however, the metal composition of the preform varies along its
length direction, indicated by arrow 140. A stratified overall
composition is indicated by multiple layers as for example at
142-145. Each layer may consist of one or more of powder form
metals M.sub.1 and M.sub.2 (or mixture thereof), or metals M.sub.1,
M.sub.2 and M.sub.3 (or mixtures thereof), or metals M.sub.1,
M.sub.2, M.sub.3, M.sub.4, M.sub.5, and M.sub.6 (or mixtures
thereof). The selection of metals and mixtures, and their
proportions as by weight, may be such as to produce an ultimate
consolidated article wherein the strength and ductility of the
article (at zones corresponding to layers 142-145) varies, in the
length direction 140; for example the hardness may decrease,
progressively, in direction 140.
[0051] In FIG. 4, each layer may consist of one or more of powder
form metals M.sub.1 and M.sub.2 (or mixture thereof), or metals
M.sub.1, M.sub.2 and M.sub.3 (or mixtures thereof), or metals
M.sub.1, M.sub.2, M.sub.3 and M.sub.4 (or mixtures thereof), or
metals M.sub.1, M.sub.2, M.sub.3, M.sub.4 and M.sub.5 (or mixtures
thereof), or M.sub.1, M.sub.2, M.sub.3, M.sub.4, M.sub.5, and
M.sub.6 (or mixtures thereof). Again, the selection of metals may
be such that ultimate strength decreases and ductility increases,
progressively and stepwise, in direction 140. Thus, for example,
the layer 142 consists of the very strong high density metal such
as tantalum adapted for high velocity penetration of armor plate,
or other hard target structures such as reinforced concrete and
steel, underground bunkers such as those used to protect chemical
and biological weapons of mass destruction (WMD). The opposite end
layer 145 may consist primarily of copper, etc. for high ductility
and performance.
[0052] Layer 142 may consist of particles of tantalum encapsulated
within layers of one or more HGM metal particles, and defined as
powder A. Layer 145 may consist of particles of low alloy steel,
defined as powder B. Intermediate layers 143 and 144 may consist of
mixtures of powder A and powder B, where the percentage by weight
of powder A decreases in successive layers in direction 140, and
the percentage by weight of powder B in successive layers increases
in direction 140.
[0053] One example of the transition layer composition in FIG. 4
would be as follows:
[0054] Layer 142 consists primarily of powder A
[0055] Layer 143 consists of 80% powder A and 20% powder B
[0056] Layer 144 consists of 60% powder A and 40% powder B
[0057] A further layer if used consists of 40% powder A and 60%
powder B
[0058] A further layer if used consists of 20% powder A and 80%
powder B
[0059] Layer 145 consists of 100% powder B
[0060] A further definition of the composite is as follows: the
body may be of a SCL or EFP shape as discussed rates, the body
consisting of at least two metals, M.sub.1 and M.sub.2, the
proportions of M.sub.1 and M.sub.2 in said body nose portion and
second body portion being different. For example, the metal M.sub.1
is tantalum, the proportion of tantalum in that nose portion being
greater than the proportion of tantalum in said second body
portion. Further, the body has third and fourth body portions along
said dimension, the proportion of tantalum in said second body
portion exceeding the proportion of tantalum in said third body
portion, and the proportion of tantalum in said third body portion
exceeding the proportion of tantalum in said fourth body
portion.
[0061] In addition, the body has first and second ends, the
consolidated metal at the first end having higher density than the
consolidated metal at the second end; and wherein the metal at the
first end consists primarily of tantalum, and the metal at the
second end consists primarily of a different density and
performance characteristic material, i.e., pyrophoric.
[0062] FIG. 5 shows by way of example a product 160 shaped
generally like that of the preform 111a. The product 160 has been
pressure consolidated, as described, to reduce its size from
preform size indicated by the broken lines 161. Forward portion 162
consists essentially of tantalum; the next layer portion 163 in
sequence consists of 20% by weight of a lower density metal (LDM)
and the balance tantalum; the next layered portion 164 in sequence
consists of 40% lower density metal (LDM) and the balance tantalum;
the next layered portion 165 in sequence consists of 60% lower
density metal and the balance tantalum; the next layered portion
166 in sequence consists of 80% lower density metal (LDM) and the
balance tantalum; and the last layer 167 consists essentially of
LDM. The layer thicknesses can be adjusted to lower increments to
improve the FGM bond.
[0063] The process of the invention yields a fully dense
microstructure and metallurgically sound bonds at 180-184, across
the layered zones 162-167.
[0064] In FIG. 7a "Process B" formed shape 120 consists of metallic
layers 121-123 with decreasing strength in direction 124. The
layers are consolidated as described above. Typical layers are:
[0065] 121--tantalum
[0066] 122--copper
[0067] 123--aluminum
[0068] Density decreases in direction 124.
[0069] In FIGS. 8a and 8b, a shaped charge liner 80 has conical
shell form, with a base 81, convex nose 82, outer side wall 83
tapering toward 82, and inner side wall 84 tapering toward 82. Wall
84 surrounds or forms inner cavity 85. The liner is formed by the
method of the invention, i.e. is a consolidated body, and has FGM
property (decreasing strength and/or ductility) in axial length
direction 87; and FGM property (decreasing hardness and/or
toughness) in wall thickness direction 88, those directions
indicated by arrows, as shown. Thus, the outer side is more ductile
than the inner side, and the nose 82 is more ductile than the base
81.
[0070] In FIGS. 9a and 9b, a penetrator 90 has combined cylindrical
and tapered shape (as at sections 90a and 90b as shown), and is a
solid body. Section 90b tapers toward tip 91. The penetrator is
formed by the method of the invention, i.e. is a consolidated body,
and has FGM property (increasing strength and/or ductility in axial
length direction 93; and FGM property (decreasing strength and/or
ductility) in center-to-side directions 94. Those directions are
indicated by arrows as shown. Thus, the tip 91 and tapered wall 96
are stronger than the base 98; and body outer side 99 is stronger
than body center 100.
[0071] In FIGS. 10a and 10b, an EFP body 110 is shown in side and
bottom views. A body hollow 111 is formed below a domed top
112.
[0072] In each of FIGS. 8a, 8b, 9a, 9b, 10a, and 10b, the body at
its toughest zone may consist of tantalum, and at less tough zone
may consist of tantalum complexed with metal or metals selected
from the above HGM group.
[0073] The basic preferred method of consolidating a body in any of
initially powdered, sintered, fibrous, sponge, or other form
capable of compaction, that includes the steps:
[0074] a) providing flowable pressure transmission particles having
carbonaceous and ceramic composition or compositions,
[0075] b) heating said particles to elevated temperature,
[0076] c) locating said heated particles in a bed,
[0077] d) positioning said body at said bed, to receive pressure
transmission,
[0078] e) effecting pressurization of said bed to cause pressure
transmission via said particles to said body, thereby to compact
and consolidate the body into desired shape, increasing its
density;
[0079] f) the body consisting essentially of one or more metals
selected from the following group: tungsten, rhenium, uranium,
tantalum, platinum, copper, gold, hafnium, molybdenum, titanium,
zirconium and aluminum;
[0080] g) said consolidated body having, along a body dimension,
one of the following characteristics:
[0081] i) decreasing strength
[0082] ii) increasing ductility
[0083] (iii) decreasing strength, and increasing ductility.
[0084] Typically, the body has varying metallic composition along
said dimension; and the varying metallic composition is
characterized by a series of zones, the metal of each zone having a
characteristic composition which differs from that of an adjacent
zone or zones. Further, the metals in at least two successive zones
consist substantially of tantalum, and tantalum consolidated with a
metal or metals selected from the group tungsten, rhenium, uranium,
tantalum, platinum, copper, gold, hafnium, molybdenum, titanium,
zirconium and aluminum.
[0085] The body may consist of powders of metals that have been
initially combined and compressed into body form, at pressure
exceeding 20,000 pounds per square inch, prior to said step e)
pressurization. At least part of the body has one of the following
forms:
[0086] i) cone
[0087] ii) lens
[0088] iii) cylinder
[0089] iv) cylinder and cone combination
[0090] v) cylinder and lens combination.
[0091] The disclosure of U.S. patent application Ser. No.
09/239,268 is also incorporated herein, by reference. Accordingly,
the consolidated tantalum may have <111> texture less than
about 2.8.times. random.
* * * * *