U.S. patent application number 11/890644 was filed with the patent office on 2009-02-12 for high-strength discontinuously-reinforced titanium matrix composites and method for manufacturing the same.
Invention is credited to Volodymyr A. Duz, Vladimir S. Moxson, Alexander E. Shapiro.
Application Number | 20090041609 11/890644 |
Document ID | / |
Family ID | 40346732 |
Filed Date | 2009-02-12 |
United States Patent
Application |
20090041609 |
Kind Code |
A1 |
Duz; Volodymyr A. ; et
al. |
February 12, 2009 |
High-strength discontinuously-reinforced titanium matrix composites
and method for manufacturing the same
Abstract
The invention relates to manufacturing the flat or shaped
titanium matrix composite articles having improved mechanical
properties such as lightweight plates, sheets for aircraft and
automotive applications, heat-sinking lightweight electronic
substrates, armor plates, etc. High-strength
discontinuously-reinforced titanium metal matrix composite (TMMC)
comprises (a) titanium matrix or titanium alloy as a major
component, (b) ceramic and/or .ltoreq.50 vol. % intermetallic hard
particles dispersed in matrix, (c) complex carbide- and/or boride
particles at least partially soluble in matrix at sintering or
forging temperatures such as .ltoreq.50 vol. % AlV.sub.2C,
AlTi.sub.2Si.sub.3, AlTi.sub.6Si.sub.3, VB.sub.2, TiVSi.sub.2,
TiVB.sub.4, Ti.sub.2AlC, AlCr.sub.2C, TiAlV.sub.2, V.sub.2C,
VSi.sub.2, Ta.sub.3B.sub.4, NbTiB.sub.4, Al.sub.3U.sub.2C.sub.3
dispersed in matrix. Method for manufacturing these TMMC materials
is disclosed. Sintered TMMC density exceeds 98% and closed
discontinuous porosity allows performing hot deformation in air
without encapsulating. Near-full density near-net shape TMMC parts
with acceptable mechanical properties were manufactured without hot
deformation.
Inventors: |
Duz; Volodymyr A.; (Hudson,
OH) ; Moxson; Vladimir S.; (Hudson, OH) ;
Shapiro; Alexander E.; (Upper Arlington, OH) |
Correspondence
Address: |
Advance Materials Products, Inc.;(ADMA Products)
1890 Georgetown Road
Hudson
OH
44236
US
|
Family ID: |
40346732 |
Appl. No.: |
11/890644 |
Filed: |
August 7, 2007 |
Current U.S.
Class: |
419/12 ; 419/17;
75/236; 75/244 |
Current CPC
Class: |
B22F 2003/175 20130101;
B22F 2999/00 20130101; B22F 2998/10 20130101; C22C 1/1084 20130101;
B22F 2999/00 20130101; B22F 2003/185 20130101; C22C 32/0047
20130101; C22C 1/1084 20130101; C22C 1/1005 20130101; B22F 3/15
20130101; B22F 3/17 20130101; B22F 3/02 20130101; B22F 3/18
20130101; B22F 3/24 20130101; B22F 3/10 20130101; B22F 3/24
20130101; B22F 2998/10 20130101 |
Class at
Publication: |
419/12 ; 419/17;
75/236; 75/244 |
International
Class: |
C22C 32/00 20060101
C22C032/00; B22F 3/12 20060101 B22F003/12 |
Claims
1. A high-strength discontinuously-reinforced titanium matrix
composite material comprising (a) a matrix of titanium or titanium
alloy as a major component, (b) ceramic and/or intermetallic hard
particles such as TiB.sub.2 and/or SiC dispersed in the matrix in
the amount of 50% or less by volume, and (c) complex carbide-
and/or boride particles that are at least partially soluble in the
matrix at the sintering or forging temperatures such as AlV.sub.2C,
AlTi.sub.2Si.sub.3, AlTi.sub.6Si.sub.3, AlTi.sub.4Si.sub.7,
Al.sub.3B.sub.48Si, VB.sub.2, V.sub.3B.sub.2, V.sub.3B.sub.4,
TiVSi.sub.2, TiVB.sub.4, Ti.sub.2AlC, Ti.sub.3AlC, AlCr.sub.2C,
TiAlV.sub.2, (Ti,V)C, (Ti,V)(B,C), V.sub.2C, V.sub.4C.sub.3,
VSi.sub.2, Ta.sub.3B.sub.4, Ta.sub.3B.sub.2, Ti.sub.2Al(B,C),
TaTiB.sub.4, NbTiB.sub.4, and/or Al.sub.3U.sub.2C.sub.3 which are
dispersed in the matrix in the amount of 20% by volume or less.
2. A method for manufacturing the high-strength
discontinuously-reinforced titanium matrix composite material
according to claim 1 comprises the following steps: (a) preparing a
basic powdered blend containing the matrix alloy or titanium
powders having a particle size less than 250 .mu.m for 95% of the
powder, and/or a mixture of the same titanium powder with the
master alloy creating an alloyed titanium matrix, and powders which
reinforce matrix during sintering or forging operations such as
ceramic powders, intermetallic powders, and/or powders of complex
carbide- and/or boride particles that are at least partially
soluble in the matrix during the sintering, forging, or other high
temperature operations, such as AlV.sub.2C, AlTi.sub.2Si.sub.3,
AlTi.sub.6Si.sub.3, AlTi.sub.4Si.sub.7, Al--.sub.3B.sub.48Si,
VB.sub.2, V.sub.3B.sub.2, V.sub.3B.sub.4, TiVSi.sub.2, TiVB.sub.4,
Ti.sub.2AlC, Ti.sub.3AlC, AlCr.sub.2C, TiAlV.sub.2, (Ti,V)C,
(Ti,V)(B,C), V.sub.2C, V.sub.4C.sub.3, VSi.sub.2, Ta.sub.3B.sub.4,
Ta.sub.3B.sub.2, Ti.sub.2Al(B,C), TaTiB.sub.4, NbTiB.sub.4, and/or
Al.sub.3U.sub.2C.sub.3, (b) preparing the reinforcing powders by
co-attrition, mechanical alloying, and/or pre-sintering and
grinding of elemental powders, (c) mixing the basic powdered blend
with the Al--V master alloy powder and/or mechanically-alloyed
powders in the predetermined ratio to obtain a chemical composition
of titanium matrix composite material, (d) consolidating at room
temperature the powder mixture containing incompletely-formed
reinforcing particles by cold isostatic pressing, die pressing,
direct powder rolling, or other processes, (e) sintering at the
temperature providing at least partial dissolution of dispersing
ceramic and/or intermetallic powders to form the reinforcing
particle system after the cooling, (f) high-temperature deformation
(forging, rolling, hot pressing, hot isostatic pressing, and/or
others) in the temperature range of 1500-2300.degree. F., (g)
cooling.
3. The high-strength discontinuously-reinforced titanium matrix
composite material according to claim 1 is characterized by
discontinuous porosity at the density over 98% from the theoretical
value.
4. The high-strength discontinuously-reinforced titanium matrix
composite material according to claim 1, wherein the matrix alloy
is selected from the group consisting of .alpha.-titanium alloys,
(.alpha.+.beta.)-titanium alloys, .beta.-titanium alloys, or
titanium aluminide alloys.
5. The high-strength discontinuously-reinforced titanium matrix
composite material according to claim 1, wherein the ceramic and/or
intermetallic hard particles dispersed in the matrix are selected
from the group consisting of SiC, TiB, TiB.sub.2, Ti.sub.3B.sub.4,
Ti.sub.2B.sub.5, B.sub.4C, ZrC, ZrB.sub.2, TaC, TaB, TaB.sub.2,
Ta.sub.3B.sub.2, B.sub.4Si, B.sub.6Si, VB, V.sub.2B, WC, NbC, NbB,
Nb.sub.3B.sub.2, Nb.sub.3B.sub.4, Al.sub.4C.sub.3, Al.sub.4C.sub.3,
AlB.sub.2, TiAl, Ti.sub.3Al, TiAl.sub.3, Al.sub.8V.sub.5, VC,
Cr.sub.7C.sub.3, HfC, UC, U.sub.2C.sub.3, and/or TiCr.sub.2.
6. The method for manufacturing the high-strength
discontinuously-reinforced titanium matrix composite material
according to claim 2, wherein the basic powdered blend is prepared
in the form of elemental powder blend or combination of elemental
powders and prealloyed powders blend.
7. The method for manufacturing the high-strength
discontinuously-reinforced titanium matrix composite material
according to claim 2, wherein co-attrition or mechanical alloying
of reinforcing elemental powders is carried out with a partial
addition of the master alloy in the amount up to 30 wt. % of the
weight of reinforcing powders.
8. The method for manufacturing the high-strength
discontinuously-reinforced titanium matrix composite material
according to claim 2, wherein mechanical alloying is carried out
with different dispersion effects, i.e. attrition for different
time to create a particular particle size distribution of
reinforcing particles.
9. The method for manufacturing the high-strength
discontinuously-reinforced titanium matrix composite material
according to claim 2, wherein the dispersing ceramic and/or
intermetallic powders are selected from the group consisting of
SiC, TiB, TiB.sub.2, Ti.sub.3B.sub.4, Ti.sub.2B.sub.5, B.sub.4C,
ZrC, ZrB.sub.2, TaC, TaB, TaB.sub.2, Ta.sub.3B.sub.2, B.sub.4Si,
B.sub.6Si, VB, V.sub.2B, WC, NbC, NbB, Nb.sub.3B.sub.2,
Nb.sub.3B.sub.4, Al.sub.4C.sub.3, Al.sub.4C.sub.3, AlB.sub.2, TiAl,
Ti.sub.3Al, TiAl.sub.3, Al.sub.8V.sub.5, VC, Cr.sub.7C.sub.3, HfC,
UC, U.sub.2C.sub.3, and/or TiCr.sub.2.
10. The method for manufacturing the high-strength
discontinuously-reinforced titanium matrix composite material
according to claim 2, wherein boron and/or carbon powders are
preliminary reacted with aluminum or aluminum-vanadium master alloy
at 800-1100.degree. C., then the obtained pre-sintered cake is
ground in powder and added into the initial mixture of composite
material components.
11. The method for manufacturing the high-strength
discontinuously-reinforced titanium matrix composite material
according to claim 2, wherein boron carbide and boron silicide
powders are preliminary reacted with titanium powder at
1200-1400.degree. C., then the obtained pre-sintered cake is ground
in powder and added into the initial mixture of composite material
components.
12. The method for manufacturing the high-strength
discontinuously-reinforced titanium matrix composite material
according to claim 2, wherein titanium boride and/or silicon
carbide powders are preliminary reacted with aluminum or
aluminum-vanadium master alloy at 900-1100.degree. C., then the
obtained pre-sintered cake is ground in powder and added into the
initial mixture of composite material components.
13. The method for manufacturing the high-strength
discontinuously-reinforced titanium matrix composite material
according to claim 2, wherein carbon powder is introduced in amount
of up to 30 wt. % in the basic powder blend, whereby the carbon is
in the form of graphite, black carbon, or pyrolytic carbon.
14. The method for manufacturing the high-strength
discontinuously-reinforced titanium matrix composite material
according to claim 2, wherein the sintering is carried out at the
temperature of 2300.degree. F. (1260.degree. C.) and higher to
provide complete densification and provide oversaturated solid
solution that will result in the formation of coherent reinforced
carbidic and/or intermetallic particles in the matrix alloy during
the cooling.
15. The method for manufacturing the high-strength
discontinuously-reinforced titanium matrix composite material
according to claim 2, wherein hot pressing, hot isostatic pressing,
or hot rolling are carried out after sintering in any
combination.
16. The method for manufacturing the high-strength
discontinuously-reinforced titanium matrix composite material
according to claim 2, wherein the resulting composite material is
characterized by density over 98% of theoretical value and
discontinued porosity after sintering that makes it possible
forging, hot pressing, hot isostatic pressing, or hot rolling
without any special protective coating, encapsulating, or
canning.
17. Use of the high-strength titanium matrix composite material
manufactured according to claim 2, wherein the as-sintered state
that is characterized by density over 98% of theoretical value and
discontinued porosity.
18. Use of the high-strength titanium matrix composite material
manufactured according to claim 2, wherein the near-net shape state
after forging, hot pressing, hot isostatic pressing, or hot rolling
performed without any special protective coating, encapsulating, or
canning, and without finishing of final product by machining and/or
chemical milling.
Description
REFERENCED CITED
TABLE-US-00001 [0001] U.S. Patent Documents 4,499,156 February 1985
Smith, et al. 428/614 4,906,930 March 1990 Abkowitz, et al. 428/469
4,917,858 April 1990 Eylon, et al. 419/28 4,968,348 November 1990
Abkowitz, et al. 75/244 4,987,033 January 1991 Abkowitz, et al.
428/469 5,336,291 August 1994 Nukami, et al. 75/10.18 5,366,570
April 1997 Mazur, et al. 148/669 5,429,877 July 1995 Eylon 428/586
5,458,705 October 1995 Mazur, et al. 148/669 5,534,353 July 1996
Kaba, et al. 428/469 5,580,403 December 1996 Mazur, et al. 148/407
5,624,505 April 1997 Mazur, et al. 148/407 5,722,037 February 1998
Chung, et al. 419/45 5,797,239 August 1998 Zaccone, et al. 420/417
5,897,830 April 1999 Abkowitz, et al. 420/417 6,029,269 February
2000 El-Soudani 2/2.5
OTHER PUBLICATIONS
[0002] Metal Handbook, 9th Edition, v.7, American Society for
Metals, Materials Park, Ohio, 1993. [0003] "Powder Metallurgy of
Titanium Alloys" F. H. Froes and D. Eylon, International Material
Reviews, 1990, vol. 35, No. 3, p. 162-182.
[0004] Primary Examiner--
[0005] Assistant Examiner--
[0006] Attorney, Agent, or Firm--
FIELD OF THE INVENTION
[0007] The present invention relates to sintered titanium metal
matrix composites discontinuously-reinforced with dispersed ceramic
and intermetallic particles such as silicon carbide, titanium
borides, vanadium carbides, titanium aluminides, etc.
BACKGROUND OF THE INVENTION
[0008] Titanium-based or titanium alloy-based metal matrix
composites (TMMC) are of particularly great interest in the
following areas: the aerospace and automotive industries, medical
implants, armor, and chemical-resistant applications due to their
high specific strength, high stiffness, low weight, and relatively
high wear resistance. The titanium or titanium alloy matrix in
these composites are reinforced by fibers or particles which have a
substantially higher hardness and elastic modulus than the matrix
alloy. Reinforcing components should be thoroughly and uniformly
dispersed in the volume of the matrix alloy to achieve the maximum
mechanical properties of the composite material. In addition, the
optimum combination of the mechanical properties of the composite
material depends upon the sizes of the reinforcing particles,
strength of the bond between the hard particles and the matrix
alloy, and the porosity of sintered composite materials.
[0009] Despite more than twenty years of experience in industrial
applications, conventional TMMC are far from perfection and being
used only on a limited scale. The limitation of their usage is
mostly associated with non optimized combination of mechanical
properties associated with remaining porosity, not uniform
chemistry and distribution of hard particles as well as absence of
well developed and optimized manufacturing processes.
[0010] For example, the method for manufacturing the Ti-6Al-4V/TiC
composite disclosed in the U.S. Pat. No. 5,722,037 provides the
density of the resulting material only about 93% of the theoretical
value even after vacuum sintering for 4 hours at 1300.degree. C.
The method includes formation of reinforcing TiC particles in the
titanium matrix by chemical reaction with hydrocarbon gas that is
more effective in the porous matrix than in the dense one.
[0011] In the U.S. Pat. No. 4,731,115 granted to Abkowitz, et al.,
a TiC/titanium alloy composite cladding material and process for
manufacturing the same are disclosed, in which blended components
are compacted by cold isostatic pressing and sintered at
2200-2250.degree. F. However, this method does not provide
sufficient density of the material, and to improve the density, the
invention further includes encasing the sintered pre-form and hot
isostatic pressing (HIP) at 1650-2600.degree. F. followed by finish
forging, rolling, or extruding. This method is not so
cost-effective due to the additional HIP step and requires encasing
that should be further removed from the final product by grinding
or chemical milling. Moreover, the HIP process does not permit
production of articles with close tolerances of their sizes.
Requirements for encapsulating are probably associated with the
interconnected porosity which prevents full consolidation and
extensive surface oxidation taking place during HIP process.
[0012] T. Kaba, et al. (U.S. Pat. No. 5,534,353) proposed
compacting a powdered component blend by cold isostatic pressing,
atomizing the product by melting and spraying, and finally,
sintering the atomized powder by HIP at 1100.degree. C.
(2012.degree. F.). The final product has improved bending strength
at room temperature, but includes atomizing in a protective
atmosphere, and it still has an interconnected porosity which
requires additional encapsulating step for the HIP process which
increases cost of manufacturing the high temperature consolidated
components.
[0013] A method for manufacturing titanium matrix composites,
according to the U.S. Pat. No. 5,458,705, is mainly based on the
precipitations of reinforcing particles from the titanium alloy
matrix during the solidification and cooling of the matrix alloy.
This means, that this method should include melting and casting of
titanium alloys at the temperature above 1600.degree. C.
(2900.degree. F.) that limits the applications of the resulting
TMMC. Any additions of actual ceramic or intermetallic hard
particles degrade flow rate during casting of molten composite
alloy, creates segregation during casting process and, as a result,
the reinforcing particles are not uniformly distributed in a
resulting TMMS alloy, restricts is not uniform and makes the
process not applicable, when the designs of the cast TMMK
structures require to have the thin cross sections.
[0014] All previous processes for manufacturing the dense titanium
matrix composites consisting of matrix alloy and reinforcing
particles by using powder metallurgy approaches have considerable
drawbacks associated with porosity and non-uniformity of
reinforcing particles distribution which degrade ductility and
strength of the TMMC and restrict applications of these
manufacturing processes. These powder metallurgy processes also
require the expensive high temperature consolidation in capsules to
prevent oxidation due to extensive porosity which escalate cost of
the manufacturing processes and limit an ability to control the
sizes of finished components.
[0015] A significant difference in structural and mechanical
properties between sintered material and the capsule produced from
non-reactive wrought metal results in non-uniform deformation and
stress concentration in the TMMC during hot deformation. Cracks in
various areas of the sintered material observed during the first
cycles of hot deformation are caused by interconnected porosity and
stress concentration. These cracks restrict maintaining a reliable
and reproducible manufacturing process through subsequent forging,
hot rolling, or other high temperature deformation.
[0016] Some of the known casting processes to produce TMMC
exhibited limitation in manufacturing the components with thin
cross sections.
[0017] Therefore, it would be desirable to provide (a) a
high-strength and fully-dense titanium matrix composites having
near full density or insignificant closed porosity after sintering
or other high temperature processing of green components, and (b) a
cost-effective method for producing such composites using blended
elemental powders or combination of pre-alloyed and elemental metal
powder blends, as well. A new composition and manufacturing method
would improve the application performance of resulting materials,
as well as eliminate destructive effect of opened porosity and
oxidation taking place during subsequent high-temperature
processing or eliminate a need for expensive encapsulation
operation which is required in order to achieve a near full density
TMMC alloy with acceptable mechanical properties.
[0018] This present invention achieves this goal by using the
complex carbides and borides as additional reinforcing components
in the Ti/TiC, Ti/TiB.sub.2, and Ti/(TiC, TiB.sub.2) composite
structures, and by providing a method through which the sintered
structure has only the closed porosity at the near full theoretical
density, while at the same time, the composite material exhibits
acceptable mechanical properties in the as-sintered conditions,
and/or if the complex shaped parts are being manufactured by
subsequent high temperature deformation,--no encasing, canning, or
encapsulating are required.
OBJECTS OF THE INVENTION
[0019] It is therefore, an object of the invention is to produce a
fully-dense, essentially uniform structure of flat and shaped
titanium metal matrix composite consisting of high-strength and
ductile matrix with uniformly distributed re-enforcing particles
providing improved mechanical characteristics such as toughness,
flexure strength, impact strength, elastic modulus, and wear
resistance.
[0020] Another object of this invention is to avoid interconnected
porosity and manufacture the sintered composite material which may
have only closed porosity and near full density after sintering,
e.g., over 98% of the theoretical value.
[0021] Yet, another object of this invention is to produce
near-full density parts from a titanium matrix composite material
that has acceptable mechanical properties without a need for
further hot deformation.
[0022] It is yet another object of this present invention is to
provide a powder metallurgy technique for manufacturing near-net
shape sintered TMMC that can be used as final product in the
as-sintered state or in the state after hot deformation without
secondary operations such as machining, chemical milling, or
others.
[0023] It is yet another additional object of the invention is to
establish a continuous cost-effective process to produce
fully-dense flat and shaped titanium alloy matrix composite parts
with controlled size tolerances from either blended elemental
powders or from a combination of the pre-alloyed and elemental
powders blend.
[0024] The nature, utility, and features of this invention will be
more apparent from the following detailed description with respect
to preferred embodiments of the invented technology.
SUMMARY OF THE INVENTION
[0025] While the use of a number of manufacturing processes
including sintering and hot deformation has previously been
contemplated in the titanium matrix composite industry, as
mentioned above, the processing limitations related to an ability
to manufacture a near full density composite structure by low cost
room-temperature consolidation, limited process stability,
inability to manufacture the components with controlled sizes when
components with close tolerances are being produced, high
production costs, defective microstructure, residual porosity, and
insufficient mechanical properties of not fully dense TMMC
articles, established a need for development of the new low cost
manufacturing processes for producing the TMMC with optimized
mechanical properties and improved performance. This invention
overcomes shortcomings in the prior art.
[0026] The goals of the invention are (a) to change the type of
porosity of the sintered semi-product from the interconnecting
porosity to only discontinuous porosity at near full density, e.g.,
over 98% of the theoretical value after sintering, and (b) to
improve mechanical properties at reduced cost of production process
for manufacturing fully-dense titanium matrix composites.
[0027] An attempt was made to produce discontinuously reinforced
TMMC using a blended elemental powder metallurgy approach. A newly
developed process allows uniform distribution of reinforcing
particles in the ductile matrix while improving the bond strength
between the reinforcing particulate and the matrix alloy.
[0028] One novelty of the invention is the use of soluble complex
borides and carbides (such as AlV.sub.2C, AlTi.sub.2Si.sub.3,
AlTi.sub.6Si.sub.3, AlTi.sub.4Si.sub.7, Al.sub.3B.sub.48Si,
VB.sub.2, V.sub.3B.sub.2, V.sub.3B.sub.4, TiVSi.sub.2, TiVB.sub.4,
Ti.sub.2AlC, Ti.sub.3AlC, AlCr.sub.2C, TiAlV.sub.2, (Ti,V)C,
(Ti,V)(B,C), V.sub.2C, V.sub.4C.sub.3, VSi.sub.2, Ta.sub.3B.sub.4,
Ta.sub.3B.sub.2, Ti.sub.2Al(B,C), TaTiB.sub.4, NbTiB.sub.4, and/or
Al.sub.3U.sub.2C.sub.3) for the reinforcement of titanium alloy
matrixes along with elemental carbide and boride particles such as
SiC, TiB, TiB.sub.2, Ti.sub.3B.sub.4, Ti.sub.2B.sub.5, B.sub.4C,
ZrC, ZrB.sub.2, TaC, TaB, TaB.sub.2, Ta.sub.3B.sub.2, VB, V.sub.2B,
WC, NbC, NbB, Nb.sub.3B.sub.2, Nb.sub.3B.sub.4, Al.sub.4C.sub.3,
Al.sub.4C.sub.3, AlB.sub.2, TiAl, Ti.sub.3Al, TiAl.sub.3,
Al.sub.8V.sub.5, VC, Cr.sub.7C.sub.3, HfC, UC, U.sub.2C.sub.3,
and/or TiCr.sub.2. Said complex borides and carbides not only
reinforce effectively the matrix titanium alloy, but also prevent
its grain growth during the sintering and subsequent heat
treatment.
[0029] Another novelty of this invention is consolidation of the
blend of matrix and reinforcing powders at room temperature,
whereby the reinforcing particles are not finally formed. The
incompletely formed intermetallic particles are not as brittle as
finally-formed intermetallics that results in effective
consolidation to high degree of green body density, and besides, in
reducing number of defects in the final product. The composite
reinforcing particles are finally formed during the hot stage of
the manufacture: sintering, forging, hot rolling, HIP, etc. These
dispersed particles are grown from the solid solution, and
therefore, they are completely compatible with the matrix
microstructure. The resulting microstructure provides significant
gain in strength of produced composite material.
[0030] There are two innovative approaches are being used in this
invention to produce the particulates for reinforcement. First
approach is preparing the reinforcing powders by co-attrition or
mechanical alloying the reinforcing elemental powders and second
approach is dealing with pre-sintering/backing and grinding the
reinforcing elemental powders. Both approaches allow application of
low cost room temperature consolidation of the particulates for
reinforcement after they are blended either with pure titanium
powder or with titanium powder mixed with master alloys, followed
by sintering operation resulting in near full density TMMC
structures. Actual formation of these TMMC structures is being
created during high temperature processing of green pre-forms, i.e.
in-situ formation of reinforced particulates uniformly distributed
in titanium or titanium alloy matrix alloy.
[0031] The preparation of pre-sintered cakes is being performed at
the temperatures which result in partial formation of the
particulate reinforcement, and the reinforcement is created during
the subsequent high temperature processing such as sintering and/or
high temperature deformation (forging, hot pressing or rolling).
These pre-sintered cakes do not have not finally formed reinforcing
particles in the matrix alloy.
[0032] These cakes are made from boron and/or carbon powders
reacted with aluminum or aluminum-vanadium master alloy at
800-1100.degree. C., boron carbide and boron silicide powders
reacted with titanium powder at 1200-1400.degree. C., and titanium
boride and/or silicon carbide powders are preliminary reacted with
aluminum or aluminum-vanadium master alloy at 900-1100.degree. C.
We discovered that reaction products such as TiB.sub.2,
Ti.sub.3SiC.sub.2, and other complex borides, carbides and
silicides have better compatibility with the crystal lattice of
matrix titanium alloys that results in additional strength and
toughness of the composite materials. The formation of such
reinforcing particles as TiB.sub.2, Ti.sub.3SiC.sub.2, and other
complex borides, carbides and silicides occurs during hot treatment
and cooling of the previously green body. Therefore, the complete
size and particle distribution are formed only in final
products.
[0033] The co-attrition or mechanical alloying of the Al--V master
alloy powder with hard reinforcing particles of above-mentioned
ceramics and intermetallics is among other novelties of this
invention.
[0034] A combination of unique properties of (i) high strength and
stiffness at temperatures up to 820.degree. C. (1500.degree. F.),
(ii) good mechanical properties at room temperature including good
ductility, (iii) improved resistance to matrix cracking, and (iiii)
very close controlled tolerances of sizes of the finished parts
which is achieved in the resulting material by forming a
discontinuous porosity of sintered semi-product followed by
effective densification during subsequent high temperature
deformation. Also, as sintered, near full density product may be
high temperature deformed (HIPped, forged, or rolled) without a
need for encapsulation.
[0035] The invented compositions and methods are suitable for the
manufacture of flat or shaped titanium matrix composite articles
having improved mechanical properties such as lightweight plates
and sheets for aircraft and automotive applications, armor plates,
heat-sinking lightweight electronic substrates, bulletproof
structures for vests, partition walls and doors, as well as
sporting goods such as helmets, golf clubs, sole plates, crown
plates, etc.
[0036] The subsequent objects, features, and advantages of our
invented material and process will be clarified by the following
detailed description of the preferred embodiments of the
invention.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION
[0037] As discussed, the present invention relates generally to the
manufacture of titanium matrix composites that are reinforced by
ceramic and/or intermetallic particles using a combination of
elemental and pre-alloyed powders (obtained by atomization or other
method), elemental metal powder blends, and/or titanium hydrides,
or a combinations thereof (i.e. combination of pre-alloyed,
elemental and/or hydrogenated powders as raw materials).
[0038] Use of preliminary prepared fine powder of Aluminum-Vanadium
master alloy plays a unique role in this process and results in
formation of highly-dense structure developed during sintering and
manufacturing a semi-finished product or finished product having
solely closed discontinuous porosity at density over 98% of the
theoretical value. The co-attrition or mechanical alloying of the
master alloy powder with hard reinforcing, ceramic and
intermetallic particles plays important role in the formation of
fine microstructure of the resulting composite material with good
bonds between the matrix and reinforcing particles developed during
subsequent sintering of room temperature consolidated (die pressed,
or cold isostatic pressed or direct powder rolled) green pre-forms.
No previously known methods, mentioned in References, allow
producing such composite structure because they used finally
structured, brittle reinforcing particles in the starting blend.
This results in crushing those brittle particles during both room
temperature consolidation and high-temperature processing (such as
forging, rolling, and hot pressing) creating multiple defects in
the composite material structure such as cracks, voids, and stress
concentrators.
[0039] The addition of complex carbide- and/or silicide particles
that are at least partially soluble in the matrix such as
AlV.sub.2C, AlTi.sub.2Si.sub.3, AlTi.sub.6Si.sub.3,
AlTi.sub.4Si.sub.7, Al.sub.3B.sub.48Si, VB.sub.2, V.sub.3B.sub.2,
V.sub.3B.sub.4, TiVSi.sub.2, TiVB.sub.4, Ti.sub.2AlC, Ti.sub.3AlC,
AlCr.sub.2C, TiAlV.sub.2, (Ti,V)C, (Ti,V)(B,C), V.sub.2C,
V.sub.4C.sub.3, VSi.sub.2, Ta.sub.3B.sub.4, Ta.sub.3B.sub.2,
Ti.sub.2Al(B,C), TaTiB.sub.4, NbTiB.sub.4, and/or
Al.sub.3U.sub.2C.sub.3 dispersed in the matrix in the amount of
.ltoreq.50 vol. % allows not only control ductility of the matrix
during any hot deformation of the sintered pre-form, but also
significantly improves the effect of particle reinforcement of the
resulting composite material. The above mentioned dispersed
particles are formed "in-situ" after final stages of the composite
manufacture: hot treatment and cooling. In order to reach the
effect of full compatibility of reinforcing particles with matrix
alloy, the process includes following steps: [0040] (a) preparing a
basic powdered blend containing the matrix alloy or titanium
powders having a particle size less than 250 .mu.m for 95% of the
powder and powders which reinforce matrix during sintering or
forging operations such as ceramic powders, intermetallic powders,
and/or powders of complex carbide- and/or boride particles that are
at least partially soluble in the matrix at the sintering or
forging temperatures such as AlV.sub.2C, AlTi.sub.2Si.sub.3,
AlTi.sub.6Si.sub.3, AlTi.sub.4Si.sub.7, Al.sub.3B.sub.48Si,
VB.sub.2, V.sub.3B.sub.2, V.sub.3B.sub.4, TiVSi.sub.2, TiVB.sub.4,
Ti.sub.2AlC, Ti.sub.3AlC, AlCr.sub.2C, TiAlV.sub.2, (Ti,V)C,
(Ti,V)(B,C), V.sub.2C, V.sub.4C.sub.3, VSi.sub.2, Ta.sub.3B.sub.4,
Ta.sub.3B.sub.2, Ti.sub.2Al(B,C), TaTiB.sub.4, NbTiB.sub.4, and/or
Al.sub.3U.sub.2C.sub.3, [0041] (b) preparing the reinforcing
powders by co-attrition, mechanical alloying, and/or pre-sintering
and grinding elemental powders, [0042] (c) mixing the basic
powdered blend with the Al--V master alloy powder and/or
mechanically-alloyed powders in the predetermined ratio to obtain a
chemical composition of titanium matrix composite material, [0043]
(d) consolidating at room temperature the powder mixture containing
incompletely-formed reinforcing particles by cold isostatic
pressing, die pressing, direct powder rolling, or other processes,
[0044] (e) sintering at the temperature providing at least partial
dissolution of dispersing ceramic and/or intermetallic powders to
form the reinforcing particle system after the cooling, [0045] (f)
high-temperature deformation (forging, rolling, hot pressing, hot
isostatic pressing, and others) in the temperature range of
1500-2300.degree. F., [0046] (g) cooling.
[0047] Complex carbides combine merits of both metals and ceramics.
Like metals, they are resistant to thermal shock, but like
ceramics, they have high strength, hardness, and thermal stability.
Such complex carbides as AlTi.sub.2Si.sub.3, AlTi.sub.6Si.sub.3,
TiVSi.sub.2, TiVB.sub.4, Ti.sub.2AlC, Ti.sub.3AlC, AlCr.sub.2C,
TiAlV.sub.2 have unique compressive plasticity at room temperature
and high temperature that allows plastic deformation of the
reinforced matrix without cracking. When the sintered composite
material pre-form is heated to 1500-1700.degree. F. for forging or
hot rolling, the complex carbides are partially dissolved in the
matrix, and the matrix alloy being freed of the carbide
reinforcements is easily deformed at these temperatures. We can use
pre-sintering, so that the alloys may be easily subjected to high
temperature deformation, but in the most cases we want to produce
TMMC without any high temperature deformation, i.e. final carbides
and other reinforcing particulates to be formed in-situ during
sintering. Complex boride and carbide powders are manufactured
separately for adding into the basic powder blend. Some of these
phases can be precipitated during cooling after hot deformation and
fix fine grain structure of forged or hot rolled composite
material.
[0048] A novel method for preparation of reinforced composite
structure was used in this invention. The composite components
(especially reinforcing ceramic or intermetallic particles are
prepared by grounding the preliminary reacted pre-sintered cakes.
These cakes are made:
[0049] (a) from boron and/or carbon powders reacted with aluminum
or aluminum-vanadium master alloy at 800-1100.degree. C.,
[0050] (b) boron carbide and boron silicide powders reacted with
titanium powder at 1200-1400.degree. C., and
[0051] (c) titanium boride and/or silicon carbide powders reacted
with aluminum or aluminum-vanadium master alloy at 900-1100.degree.
C.
[0052] These pre-sintered cakes are ground for dispersed particles
which are subsequently mixed with the basic elemental powder blend.
We discovered that reaction products such as TiB.sub.2, TiC,
Ti.sub.3SiC.sub.2, and other complex borides, carbides and
silicides have better compatibility with the crystal lattice of
matrix titanium alloys that results in additional strength and
toughness of the composite materials.
[0053] We found that boron carbide B.sub.4C powder reacts with
titanium powder at 1200-1400.degree. C. with the formation of both
titanium boride phases TiB.sub.2, TiB, and titanium carbide TiC. If
titanium powder is taken in the excessive amount, these reaction
products are synthesized immediately in the contact with titanium
particles that improve the bond between reinforcing borides and
carbides with the main component of the matrix alloy.
[0054] Similar reaction occurs between silicon carbide SiC and
titanium with the formation of very effective reinforcing particles
of Ti.sub.3SiC.sub.2.
[0055] The co-attrition or mechanical alloying of the Al--V master
alloy powder with hard reinforcing particles of above-mentioned
ceramics and intermetallics is among other novelties of this
invention.
[0056] The foregoing examples of the invention are illustrative and
explanatory. The examples are not intended to be exhaustive and
serve only to show the possibilities of the invented
technology.
Example 1
[0057] A TiB.sub.2-- and SiC-reinforced titanium composite material
based on the Ti-6Al-4V alloy matrix was manufactured by (a)
preparing a basic powder blend containing titanium powder and
having a particle size .ltoreq.200 mesh (.ltoreq.74 microns) for
95% of the powder, 5% of graphite, 2.5% of dispersing SiC powder,
7.5% of dispersing TiB.sub.2 particles, and 2.5% of dispersing
powders of AlTi.sub.2Si.sub.3, (Ti,V)(B,C), and TiVB.sub.4 complex
intermetallic particles partially soluble in the matrix at
1500-2300.degree. F., (b) making a powder of Al--V master alloy
having a particle size of 10 .mu.m and less, (c) co-attrition of
30% of this master alloy powder with reinforcing powders, (d)
mixing the basic powder blend with the master alloy powder and
reinforcing particles at the weight ratio between titanium powder
and master alloy of 9:1 to obtain a chemical composition of
titanium matrix composite material, (e) compacting the powder
mixture at room temperature by cold isostatic pressing, (f)
sintering at 2300.degree. F., (g) forging at 1600.degree. F., and
(h) cooling.
[0058] Sintered semi-product had density 98.9% with closed
discontinuous porosity that allowed to perform the forging
operation in air without encapsulating the sintered preform. The
resulting (TiB.sub.2--SiC)/Ti-6Al-4V composite material has 100%
density, and exhibits improved yield strength at room temperature
and at 930.degree. F. (500.degree. C.).
Example 2
[0059] A carbide-reinforced titanium composite material based on
the Ti-6Al-4V alloy matrix was manufactured by (a) preparing a
basic powder blend containing titanium powder having a particle
size .ltoreq.140 mesh (.ltoreq.100 .mu.m) for 95% of the powder, 2%
of graphite, 15% of dispersing SiC powder, and 4% of dispersing
AlV.sub.2C, Ti.sub.2AlC, and V.sub.2C particles partially soluble
in the matrix at 1500-2300.degree. F., (b) making a powder of Al--V
master alloy having a particle size of 10 .mu.m and less, (c)
mixing the basic powder blend with the master alloy powder, in the
ratio of 9:1 to obtain a chemical composition of titanium matrix
composite material, (d) compacting the powder mixture at room
temperature by die-pressing, (e) sintering at 2350.degree. F., (f)
forging at 1600.degree. F., and (g) cooling.
[0060] Sintered semi-product had a density of 99% with closed
discontinuous porosity that allowed it to carry out forging in open
air without encapsulating (or encasing). The resulting
carbide-reinforced Ti-6Al-4V matrix composite material has 100%
density, and it exhibits improved yield strength at room
temperature and at 930.degree. F. (500.degree. C.), and satisfied
oxidation resistance up to 1470.degree. F. (800.degree. C.).
Example 3
[0061] The titanium matrix composite was manufactured using the
same raw materials for Ti-6Al-4V matrix alloy and carbide
reinforcements, and the same mode of sintering as in Example 1. The
final hot deformation was made by hot rolling at 1650.degree. F.
instead of forging.
[0062] The resulting TiC/Ti-6Al-4V composite material also had 100%
density, and exhibited satisfied yield strength at room temperature
and at 930.degree. F. (500.degree. C.).
Example 4
[0063] The boride-reinforced titanium composite material based on
the Ti-6Al-4V alloy matrix was manufactured by (a) preparing a
basic powder blend containing titanium powder having a particle
size .ltoreq.200 mesh (.ltoreq.74 microns) for 95% of the powder,
5% of graphite, 12.5% of the dispersing TiB.sub.2 powder, and 2.5%
of the dispersing VB.sub.2, TiVB.sub.4, and NbTiB.sub.4, complex
boride particles partially soluble in the matrix at
1500-2300.degree. F., (b) the TiB.sub.2 powder was prepared by
reacting B.sub.4C powder with titanium powder at 2280.degree. F.
(1250.degree. C.) followed by grinding the pre-sintered cake, (c)
making a powder of Al--V master alloy having a particle size of 10
Mm and less, (d) mixing the basic powder blend with the master
alloy powder at the ratio of 9:1 to obtain a chemical composition
of titanium matrix composite material, (e) compacting the powder
mixture at room temperature by cold isostatic pressing, (f)
sintering at 2450.degree. F., and (g) cooling.
[0064] The resulting composite material has density 99.3% of the
theoretical value with closed discontinuous porosity and exhibits
acceptable yield strength at room temperature and at 930.degree. F.
(500.degree. C.). The cost-effective plate of this material was
used as final product without hot deformation.
* * * * *