Abstract: A method to produce high temperature oxidation resistant metal matrix composites by fiber diameter grading, which comprises the steps of (a) laying up an alloy/fiber preform consisting of a plurality of alternating layers of metal alloy and fibers and (b) consolidating the preform under suitable conditions, wherein the layers of fibers in the preform are graduated so that fiber density is lower nearer what will become the exposed surface of the composite and higher toward the interior of the composite. The difference in fiber density is achieved by spacing the near-surface fibers further apart than the interior fibers.

Abstract: A method for protecting a titanium aluminide substrate against environmental degradation at higher temperatures, which comprises applying a layer of a ductile titanium alloy to at least one exterior surface of the substrate and applying an oxidation resistant coating to the exterior surface of the ductile layer. The titanium aluminide substrate may be monolithic or a fiber-reinforced composite structure. The oxidation resistant coating is an ion-plated coating of (a) a noble metal, such as gold or platinum, or (b) a coating of tungsten followed by an ion-plated coating of a noble metal.

Abstract: A method to produce high temperature oxidation resistant metal matrix composites by fiber diameter grading which comprises the steps of (a) laying up an alloy/fiber preform consisting of a plurality of alternating layers of metal alloy and fibers and (b) consolidating the preform under suitable conditions, wherein fibers of at least two diameters are employed and wherein the layers of fibers in the preform are graduated so that larger diameter fibers are located nearer what will become the exposed surface of the composite and smaller diameter fibers are located toward the interior of the composite.

Abstract: The microstructure of alpha-2 and orthorhombic titanium aluminide alloy cast and ingot metallurgy articles is refined by: (a) hydrogenating the article at a temperature at or slightly below the .beta.-transus temperature of the alloy; (b) cooling the article, under a positive partial pressure of hydrogen, to a temperature about 20 to 40 percent below the .beta.-transus; and (c) dehydrogenating the article.

Abstract: An internally reinforced hollow structure is described which comprises a layer of titanium metal matrix composite applied to the internal surfaces of structural segments comprising the hollow structure, the segments then being joined to form the desired hollow structure.

Abstract: A method for producing hot worked gamma titanium aluminide alloy articles which comprises the steps of:(a) providing a prealloyed gamma titanium aluminide alloy powder;(b) filling a suitable die or mold with the powder;(c) hot isostatic press (HIP) consolidating the powder in the filled mold at a pressure of 30 Ksi or greater and at a temperature below the alpha-two+gamma eutectoid temperature of the alloy to produce a preform;(d) hot working the preform at a temperature at or below the alpha-two+gamma eutectoid temperature of the alloy; and(e) optionally, heat treating the hot worked article.By hot working the preform at or below the alpha-two+gamma eutectoid temperature, the fine, uniform, isotropic microstructure of the preform is maintained, allowing a large metal flow and good shape definition with no edge cracking.

Abstract: The fracture resistance of titanium alloy matrix composites is increased by one of two methods. One method comprises the steps of consolidating a titanium alloy-fiber preform under suitable conditions to provide a metal matrix composite and thermally treating the thus-prepared composite at a temperature above the beta-transus temperature of the alloy for a brief time. In the second method, a composite having increased fracture resistance is produced by consolidating an alloy-fiber preform at a temperature above the normal consolidation temperature for a time less than the normal consolidation time.

Abstract: A method to increase the fracture resistance of titanium alloy matrix composites which comprises thermally treating a composite at a temperature about 5 to 10% above the beta-transus temperature of the alloy for about 4 to 60 minutes.

Abstract: A method for producing hollow titanium alloy articles which comprises casting a plurality of segments which can be joined to provide a unitary, hollow article, treating the cast segments in such manner as to refine the microstructure of the segments and superplastic forming/diffusion bonding the segments into the desired hollow article.

Abstract: A method for producing fiber reinforced titanium alloy articles which comprises casting a plurality of segments which can be joined to provide a unitary article, wherein at least one-half of the segments comprise at least one shallow cavity, treating the cast segments in such manner as to refine the microstructure of the segments, filling the cavity or cavities with reinforcing fibers and superplastic forming/diffusion bonding the segments into the desired article.

Abstract: A method for fabricating a titanium aluminide composite structure consisting of a filamentary material selected from the group consisting of silicon carbide, silicon carbide-coated boron, boron carbide-coated boron, titanium boride-coated silicon carbide and silicon-coated silicon carbide, embedded in an alpha-2 titanium aluminide metal matrix, which comprises the steps of providing a beta-stabilized Ti.sub.3 Al foil containing a sacrificial quantity of beta stabilizer element in excess of the desired quantity of beta stabilizer, fabricating a preform consisting of alternating layers of foil and a plurality of at least one of the aforementioned filamentary materials, and applying heat and pressure to consolidate the preform. In another embodiment of the invention, the beta-stabilized Ti.sub.3 Al foil is coated on at least one side with a thin layer of sacrificial beta stabilizer.

Abstract: A method for fabricating a composite structure consisting of a filamentary material selected from the group consisting of silicon carbide, silicon carbide-coated boron, boron carbide-coated boron, titanium boride-coated silicon carbide and silicon-coated silicon carbide, embedded in an alpha-2 titanium aluminide metal matrix, which comprises the steps of modifying the desired filamentary material with at least one beta stabilizer, providing a beta-stabilized Ti.sub.3 Al foil, fabricating a preform consisting of alternating layers of foil and a plurality of at least one of the beta stabilizer-coated filamentary materials, and applying heat and pressure to consolidate the preform.The composite structure fabricated using the method of this invention is characterized by its lack of a denuded zone and absence of fabrication cracking.

Abstract: A method of producing titanium alloy articles having a desired microstructure which comprises the steps of:(a) providing a prealloyed titanium alloy powder;(b) filling a suitable die or mold with the powder;(c) hot isostatic press (HIP) consolidating the powder in the filled mold at a pressure of 30 Ksi or greater and at a temperature of about 60 to 80 percent of the beta transus temperature of the alloy, in degrees C.In another embodiment of the invention, the prealloyed titanium aluminide alloy powder is hydrogenated to about 0.1 to 1.0 wt. % prior to die filling and consolidation. The compacted article is vacuum annealed to remove hydrogen from the article after removal of the die material.

Abstract: A method for producing titamium alloy articles having a desired microstructure which comprises the steps of:(a) providing a prealloyed gamma titanium aluminide alloy powder;(b) filling a suitable die or mold with the powder;(c) consolidating the powder in the filled mold at a pressure of 30 Ksi or greater and at a temperature of about 70 to 95 percent of the alpha-2+gamma eutectoid temperature of the alloy, in degrees C.

Abstract: An improved process for producing near-alpha and alpha+beta titanium alloy axisymmetric components with high fatigue resistance which comprises the steps of:(a) providing a beta processed near-alpha or alpha+beta titanium alloy component;(b) torque deforming the component; and(c) alpha+beta recrystallization annealing the resulting torque-deformed component.

Abstract: Near-alpha and alpha+beta titanium alloy components are produced by a process which comprises the steps of forging an alloy billet to a desired shape at a temperature at or above the beta-transus temperature of the alloy to provide a forged component, heat treating the forged component at a temperature approximately equal to the beta-transus temperature of the alloy, cooling the component at a rate in excess of air cooling to room temperature, annealing the component at a temperature in the approximate range of 10 to 20% below said beta-transus temperature for about 4 to 36 hours, and air cooling the component to room temperature.

Abstract: A method for fabricating a titanium aluminide composite structure consisting of a filamentary material selected from the group consisting of silicon carbide, silicon carbide-coated boron, boron carbide-coated boron, titanium boride-coated silicon carbide and silicon-coated silicon carbide, embedded in an alpha-2 titanium aluminide metal matrix, which comprises the steps of providing a first beta-stabilized Ti.sub.3 Al powder containing a desired quantity of beta stabilizer, providing a second beta-stabilized Ti.sub.3 Al powder containing a sacrificial quantity of beta stabilizer in excess of the desired quantity of beta stabilizer, coating the filamentary material with the second powder, fabricating a preform consisting of the thus-coated filamentary materials surrounded by the first powder, and applying heat and pressure to consolidate the preform.The composite structure fabricated using the method of this invention is characterized by its lack of a denuded zone and absence of fabrication cracking.

Abstract: Processes for producing titanium alloy SPF/DB components, particularly structural panels, are provided.In one embodiment, the process comprises providing rapidly solidified titanium alloy sheetstock, providing a plurality of rapidly solidified titanium alloy ribbons or strips, forming the ribbons into waveform structures, assembling a plurality of these waveform structures to produce a honeycomb core, positioning this core between face sheets, and bonding the core to the face sheets.In another embodiment the process comprises providing rapidly solidified titanium alloy sheetstock, superplastically forming at least one piece of sheetstock into a shaped piece having spaced apart, parallel bonding regions, positioning this shaped piece between two face sheets, and bonding the shaped piece to each face sheet.

Abstract: A method for producing a titanium alloy powder metallurgy article having high resistance to loading and creep at high temperature is described and comprises the steps of simultaneously pressing a preselected quantity of titanium alloy powder at from 15 to 60 ksi and heating the powder to a temperature just below the beta transus temperature of the alloy to promote beta to alpha phase transformation in the alloy, and then slowly cooling the compacted powder under pressure.

Abstract: A method for producing foil of titanium aluminide is described which comprises providing a preselected quantity of blended powder of chloride free commercially pure elemental titanium, aluminum and other alloying metal(s) in preselected proportions, rolling the blended powder into a green foil, sintering the green foil, and thereafter pressing the sintered foil to full density.