High-strength discontinuosly-reinforced titanium matrix composites and method for manufacturing the same

Abstract

The method for manufacturing high-strength discontinuously-reinforced titanium matrix composite comprises the following steps: (a) preparing a basic powdered blend containing the matrix alloy or titanium powders having a particle size <250 μm for 95% of the powder and powders, which reinforcing matrix during high-temperature operations, such as blended elemental reinforcing powders, ceramic powders, intermetallic powders, and/or powders of complex carbide- and/or boride particles that are at least partially soluble in the matrix, (b) preparing reinforcing powders by co-attrition, mechanical alloying, or pre-sintering of blended elemental powders with each other and graphite, (c) mixing the basic powdered blend with the Al-V master alloy powder, and co-attrited, mechanically-alloyed powders, and pre-sintered powders in the predetermined ratio to obtain a chemical composition of titanium matrix composite material, (d) compacting the powder mixture at room temperature by any of room temperature consolidation process, (e) sintering at the temperature providing at least partial dissolution of dispersing ceramic and/or intermetallic powders, (f) high-temperature deformation at the temperature range of 1500-2300° F. resulting in additional in-situ formation of re-enforced particulates, and (g) cooling.

Description

The present application is a Divisional Application of U.S. application Ser. No 11/890,644 filed on Aug. 7, 2007, the entire contents of which is incorporated herein by reference.

FIELD OF THE INVENTION

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

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.

Despite more than twenty years of experience in industrial applications. conventional TMMC are far from perfection and being used only on a limited basis. The limitation of their usage is mostly associated with non-optimized combination of mechanical properties caused by remaining porosity, not uniform chemistry and distribution of hard particles as well as absence of well developed and optimized manufacturing processes.

For example, the method for manufacturing the Ti-6Al-4V/TiC composite disclosed in the U.S. Pat. No. 5,722,037 provides the low densities of the resulting material which is only about 93% of the theoretical value even after vacuum sintering fix 4 hours at 1300° 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.

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° F. However, this method does not provide sufficient density of the material, and to improve the density, the invention further includes encapsulating the sintered pre-form and hot isostatic pressing (HIP) at 1650-2600° F. followed by subsequent forging, rolling. or extruding. This method is not so cost-effective due to the additional HIP operation and besides of this, it requires encapsulation, which 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 mostly associated with the interconnected porosity. which prevents full consolidation and creates extensive surface oxidation taking place during HIP process.

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° C. (2012° F.). The final product has improved bending strength at room temperature, but includes expensive process of atomization in a protective atmosphere. and the components produced by this process are still exhibit an interconnected porosity. Additional encapsulating and HIP operation are required for closing this porosity. which increases cost of manufacturing the components with acceptable combination of their properties.

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° C. (2900° F.) and these high temperatures would destroy the re-enforcement. The created ceramic particles 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 TMMC. Degraded flow rate also restricts an ability torn produce the cast TMMC components with thin cross sections.

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 in escalate cost of the manufacturing processes and limit an ability to control the sizes of finished components.

A significant difference in (structural and) mechanical properties between sintered TMMC material and the non-reactive wrought metal being used for manufacturing the encapsulations results in non-uniform deformation and stress concentration in during high temperature formation of the TMMC alloys. Cracks in various areas of the sintered material observed during the first cycles of hot deformation are caused by both interconnected porosity and stress concentration. These cracks restrict maintaining a reliable and reproducible manufacturing process during subsequent forging. hot rolling, or other high temperature deformation.

Some of the known casting processes to produce TMMC exhibited limitation in manufacturing the components with thin cross sections.

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. It also requires to apply a low cost room temperature consolidation processes such as die-pressing, direct powder rolling, cold iso-static pressing, but the presence of re-enforced particles restricts applications of these low cost consolidation processes. A new composition and manufacturing method, which would improve the application performance of resulting. materials, as well as eliminate destructive effect of opened porosity and oxidation so taking place during subsequent high-temperature processing or eliminate a need for expensive encapsulation operation is required in order to achieve a near full density TMMC alloy with acceptable mechanical properties.

This present invention achieves this goal by using not only complex carbides and borides as additional reinforcing components in the Ti/TiC, Ti/TiB2, and Ti/(TiC, TiB2) composite structures but also formation of reinforcing particles by solid-state chemical reactions during co-attrition and mechanical alloying of carbide- and boride-forming elemental powders, which react with each other and with graphite. The content of carbides in the initial mixture may be minimized in order to be able to consolidate the components at room temperature. Usage a co-attrition and mechanical alloying to produce the alloying additions to the blends has positive effect because the carbide forming elements are still ductile during room temperature consolidation. Also, co-attrition, mechanical alloying, and pre-sintering of blended elemental powders allow to control the particle size of reinforcing particulates and optimize their distribution by selecting temperature and time during sintering operation. Finally, this new approach provides the sintered structure having the closed porosity with no interconnected voids 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 in performing these additional operations.

OBJECTS OF THE INVENTION

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 of controlled particle size that provides improved mechanical characteristics such as fracture toughness. flexure strength, impact strength, elastic modulus, and wear resistance.

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.

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.

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.

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 in controlled size tolerances from either blended elemental powders or from a combination of the pre-alloyed and elemental powders blend.

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

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, 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.

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.

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.

One novelty of the invention is the use of soluble complex borides and carbides (such as AlV₂C, AlTi₂Si₃, AlTi₆Si₃, AlTi₄Si₇, Al₃B₄₈Si, VB₂, V₃B₂, V₃B₄TiVSi₂, TiVB₄, Ti₂AlC, Ti₃AlC, AlCr₂C, TiAlV₂, (Ti,V)C, (Ti,V)(B,C), V₂C, V₄C₃, VSi₂, Ta₃B₄, Ta₃B₂, Ti₂Al(B,C), TaTiB₄, NbTiB₄, and/or Al₃U₂C₃) for the reinforcement of titanium alloy matrixes along with elemental carbide and boride particles such as SiC, TIB, TiB₂, Ti₃B₄, Ti₂B₅, B₄C, ZrC, ZrB₂, TaC, TaB, TaB₂, Ta₃B₂, VB, V₂B, WC, NbC, NbB, Nb₃B₂, Nb₃B₄, Al₄C₃, Al₄C₃, AlB₂, TiAl, Ti₃Al, TiAl₃, Al₃V₅, VC, Cr₇C₃, HfC, UC,U₂C₃, B₄Si, B₆Si, and/or TiCr₂. 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.

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 so 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.

There are two innovative approaches arc 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 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.

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.

These cakes are made from boron and/or carbon powders reacted with aluminum or aluminum-vanadium master alloy at 800-1100° C., boron carbide and boron silicide powders in reacted with titanium powder at 1200-100° C., and titanium boride and/or silicon carbide powders are preliminary reacted with aluminum or aluminum-vanadium master alloy at 900-1100° C. We discovered that reaction products such as TB₂. Ti₃SiC₂, 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 TiB₂. Ti₃SiC₂. 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.

The co-attrition or mechanical alloying of the Al-V master alloy powder with blended elemental carbide-forming elements co-attrited or mechanically alloyed with graphite powders. as well as with hard reinforcing particles of above-mentioned ceramics and intermetallics is among other novelties of this invention.

A combination of unique properties of (i) high strength and stiffness at temperatures up to 820° C. (1500°), (ii) good mechanical properties at room temperature including good ductility, (iii) improved resistance to matrix cracking. and (iv) 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.

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.

The subsequent objects, features, and advantages of our invented material and process will be clarified by the following detailed description of the preferred embodiments oldie invention.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION

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).

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 blended elemental carbide-forming elements co-attrited or mechanically alloyed with graphite powders, as well as 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 particle 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.

The addition of complex carbide- and/or silicide particles that are at least partially soluble in the matrix such as AlV₂C, AlTi₂Si₃, AlTi₆Si₃, AlTi₄Si₇, Al₃B₄₈Si, VB₂, V₃B₂, V₃B₄, TiVSi₂, TiVB₄, Ti₂AlC, Ti₃AlC, AlCr₂C, TiAlV₂, (Ti,V)C, (Ti,V)(B,C), V₂C,V₄C₃, VSi₂, Ta₃B₄, Ta₃B₂, Ti₂Al(B,C), TaTiB₄, NbTiB₄, and/or Al₃U₂C₃, UC, U₂C₃, B₄Si, B₆Si, and/or TiCr₂ dispersed in the matrix in the amount of 5,50 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:

(a) preparing a basic powdered blend containing the matrix alloy or titanium powders having a particle size less than 250 μm 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 AlV₂C, AlTi₂Si₃, AlTi₆Si₃, Al₃B₄₈Si, VB₂, V₃B₂, V₃B₄, TiVSi₂, TiVB₄, Ti₂AlC, Ti₃AlC, AlCr₂C, TiAlV₂, (Ti,V)C, (Ti,V)(B,C), V₂C, V₄C₃, VSi₂, Ta₃B₄, Ta₃B₂, Ti₂Al(B,C), TaTiB₄, NbTiB₄, Al₃U₂C₃, UC, U₂C₃, B₄Si, B₆Si, and/or TiCr₂.

(b) preparing additional reinforcing powders having controlled particle size by co-attrition, mechanical alloying, pre-sintering and grinding of elemental powders processed with the graphite powders,

(c) mixing the basic powdered blend with the Al-V master alloy powder and/or mechanically-alloyed reinforcing 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 others) in the temperature range of 1500-2300° F. for further in-situ formation of re-enforced particulates,

(g) cooling.

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 AlTi₂Si₃, AlTi₆Si₃, TiVSi₂, TiVB₄, Ti₂AlC, AlCr₂C, TiAlV₂ 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° F. fear 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.

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 grinding the preliminary reacted pre-sintered cakes. These cakes are made by:

(a) heating boron with the powder mixture to temperatures in the range of 800-100° C. when boron and/or carbon powders reacted with aluminum or aluminum-vanadium master alloy.

(b) heating to temperatures in the range of 900-100° C. when titanium boride and/or silicon carbide powders reacted with aluminum or aluminum-vanadium master alloy, and

(c) heating to temperatures in the range of 1200-1400° C. when boron carbide and boron silicide powders reacted with titanium powder, and

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 TiB₂, TiC, Ti₃SiC₂, 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.

We found that boron carbide B₄C powder reacts with titanium powder at 1200-1400° C.; with the formation of both titanium boride phases TiB₂, 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 horides and carbides with the main component of the matrix alloy.

Similar reaction occur between silicon carbide SiC and titanium with the formation of very effective reinforcing particles of Ti₃SiC₂.

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.

The foregoing examples of the invention are illustrative and explanatory. The exampled are not intended to be exhaustive arid serve only to show the possibilities of the invented technology.

EXAMPLE 1

A TiB₂ 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 ≦200 mesh (≦74 microns) for 95% of the powder, 5% of graphite, 2.5% of dispersing SiC powder. 7.5% of dispersing TiB₂ particles, and 2.5% of dispersing powders of AlTi₂Si₃, (Ti, V)(B,C), and TiVB₄ complex intermetallic particles partially soluble in the matrix at 1500-2300° F., (b) co-attrition and mechanical alloying of the basic blend components to manufacture reinforcing particles of complex composition and controlled particle size, (c) making a powder of Al-V master alloy having a particle size of 10 μm and less, (d) co-attrition of 30% of this master alloy powder with reinforcing powders of graphite. SiC powder, TiB₂ particles, and powders of AlTi₂Si₃, (Ti,V)(B,C), and TiVB₄ complex intermetallic particles, (e) 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, (f) compacting the powder mixture at room temperature by cold isostatic pressing, (g) sintering at 2300° F, (h) forging at 1600° F., and (i) cooling.

Sintered semi-product had density 98.9% with closed discontinuous porosity that allowed to perform the forging operation in air without encapsulating the sintered pre-firm. The resulting (TiB₂-SiC)/Ti-6Al-4V composite material has 100% density, and exhibits improved yield strength at room temperature and at 930° F. (500° C.).

EXAMPLE 2

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 ≦140 mesh (≦100 μm) for 95% of the powder, 2% of graphite, 15% of dispersing SiC powder, and 4% of dispersing AlV₂C. Ti₂AlC, and V₂C particles partially soluble in the matrix at 1500-2300° F., (b) co-attrition and mechanical alloying of the basic blend components to manufacture reinforcing particles of complex composition and controlled particle size, (c) making a powder of Al-V master alloy having a particle size of 10 μm and less, (d) mixing and co-attriting 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 die-pressing, (f) sintering at 2350° F., (g) forging at 1600° F., and (h) cooling.

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° F. (500° C.), and satisfied oxidation resistance up to 1470° F. (800° C.).

EXAMPLE 3

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° F. instead of forging.

The resulting TiC/Ti-6Al-4V. composite material also had 100% density, and exhibited satisfied yield strength at room temperature and at 930° F. (500° C.).

EXAMPLE 4

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 ≦200 mesh (≦74 microns) for 95% of the powder, 5% of graphite, 12.5% of the dispersing TiB₂ powder, and 2.5% or the dispersing VB₂, TiVB₄, and NbTiB₄, complex boride particles partially soluble in the matrix at 1500-2300° F., (b) the TiB₂ powder was prepared by reacting B₄C powder with titanium powder at 2280° F. (1250° C.) followed by grinding the pre-sintered cake, (c) making a powder of Al-V master alloy having a particle size of 10 μm and less. (d) mixing the basic powder blend and co-attriting 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° F., and (g) cooling.

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° F., (500° C.). cost-effective plate of this material was used as final product without hot deformation.

Claims

1. A method for manufacturing a high-strength discontinuously-rein (breed titanium matrix composite material comprising the following steps:

(a) preparing a basic powdered blend containing a matrix alloy or titanium powders having a particle size less than 250 μm for 95% of the powder, and a mixture of the same titanium powder with a master alloy creating an alloyed titanium matrix, and powders which reinforce matrix during sintering or forging operations such as ceramic powders, intermetallic powders, and powders of complex carbide- and boride particles that are at least partially soluble in the matrix during the sintering, forging, or other high temperature operations, such as at least one AlV2C, AlTi2Si3, AlTi6Si3, AlTi4Si7, Al3B48Si, VB2, V3B2, V3B4, TiVSi2, TiVB4, Ti2AlC, Ti3AlC, AlCr2C, TiAlV2, (Ti,V)C, (Ti,V)(B,C), V2C, V4C3, VSi2, Ta3B4, Ta3B2, Ti2Al(B,C), TaTiB4, NbTiB4, and Al3U2C3,

(b) preparing reinforcing powders by co-attrition, mechanical alloying, or pre-sintering and grinding of elemental metal powders and graphite,

(c) co-attrition of the basic powdered blend (a) with the Al-V master alloy powder 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 a temperature providing at least partial dissolution of dispersing ceramic and/or intermetallic powders to form the reinforcing particle system after cooling.

(f) high-temperature deformation (forging, rolling, hot pressing, hot isostatic pressing, and/or others) in a temperature range of 1500-2300° F.,

(g) cooling.

2. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, wherein the ceramic and intermetallic hard particles dispersed in the matrix are selected from the group consisting of SiC, TiB. TiB2. Ti3B4, Ti2B4C, ZrC, ZrB2, TaC, TaB, TaB2, Ta3B2, B4Si, VB, V2B, WC, NbC, NbB, Nb3B2, Nb3B4, Al4C3, Al4C3, AlB2, TiAl, Ti3Al, TiAl3Al8V5, VC, Cr7C3, HfC, UC, U2C3, and TiCr2.

3. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, wherein the basic powdered blend is prepared in the form of elemental powder blend or combination of elemental powders, graphite, and prealloyed powders blend.

4. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, wherein co-attrition or mechanical alloying of reinforcing elemental powders is carried out with a partial addition of the master alloy in an amount up to 30 wt. % of the weight of reinforcing powders.

5. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, 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.

6. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, wherein boron and carbon powders are preliminary reacted with aluminum or aluminum-vanadium master alloy at 800-1100° C., then obtained pre-sintered cake is ground in powder and added into the initial mixture of composite material components.

7. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, wherein boron carbide and boron silicide powders are preliminary reacted with titanium powder at 1200-1400° C., then obtained pre-sintered cake is ground in powder and added into the initial mixture of composite material components.

8. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, wherein titanium boride and silicon carbide powders are preliminary reacted with aluminum or aluminum-vanadium master alloy at 900-1100° C. then obtained pre-sintered cake is ground in powder and added into the initial mixture of composite material components.

9. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, 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.

10. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, wherein the sintering is carried out at a temperature of 2300° F. (1260° C.) and higher to provide complete densification and provide oversaturated solid solution that will result in a formation of coherent reinforced carhidic and/or intermetallic particles in the matrix alloy during the cooling.

11. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, wherein hot pressing, hot isostatic pressing, or hot rolling are carried out after sintering in any combination.

12. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, 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.

13. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, wherein the resulting composite material after step (e) has discontinued porosity and density over 98% of theoretical value.

14. The method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material according to claim 1, wherein a near-net shape state after forging, hot pressing, hot isostatic pressing, or hot rolling is performed without any special protective coating, encapsulating, or canning, and without finishing of final product by machining and/or chemical milling.

15. A method for manufacturing a high-strength discontinuously-reinforced titanium matrix composite material comprising the following steps:

(a) preparing a basic powdered blend containing a matrix alloy or titanium powders having a particle size less than 250 μm for 95% of the powder, or a mixture of the same titanium powder with a master alloy creating an alloyed titanium matrix, and powders which reinforce matrix during sintering or forging operations such as ceramic powders, intermetallic powders, or powders of complex carbide- and boride particles that are at least partially soluble in the matrix during the sintering, forging, or other high temperature operations, such as at least one of AlV2C, AlTi2Si3, AlTi6Si3, AlTi4Si7, Al3B48Si, VB2, V3B2, V3B4, TiVSi2, TiVB4, Ti2AlC, Ti3AlC, AlCr2C, TiAlV2, (Ti,V)C, (Ti,V)(B,C), V2C, V4C3, VSi2, Ta3B4, Ta3B2, Ti2Al(B,C), TaTiB4, NbTiB4, and Al3U2C3.

(b) preparing reinforcing powders by co-attrition, mechanical alloying, and pre-sintering and grinding of elemental metal powders and graphite,

(c) co-attrition of the basic powdered blend (a) with the Al-V master alloy powder and 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 a temperature providing at least partial dissolution of dispersing ceramic and/or intermetallic powders to form the reinforcing particle system after cooling,

(f) high-temperature deformation (forging, rolling, hot pressing, hot isostatic pressing, and/or others) in a temperature range of 1500-2300° F.

(g) cooling.

16. The method for manufacturing the high-strength discontinuously-reinforced titanium matrix composite material according to claim 15, wherein boron or carbon powders are preliminary reacted With aluminum or aluminum-vanadium master alloy at 800-1100° C. then the obtained pre-sintered cake is ground in powder and added into the initial mixture of composite material components.

17. The method for manufacturing the high-strength discontinuously-reinforced titanium matrix composite material according to claim 15, wherein titanium boride or silicon carbide powders are preliminary reacted with aluminum or aluminum-vanadium master alloy at 900-1100° C., and then obtained pre-sintered cake is ground in powder and added into the initial mixture of composite material components.