Abstract: Quenching a work piece made of a titanium alloy having a temperature higher than 800° C. to a temperature lower than 500° C. at a cooling rate greater than 10° C./second between 800° C. and 500° C. is used to render the cooled work piece containing &agr;″ phase as a major phase. The titanium alloy composition contains at least one isomorphous beta stabilizing element selected from Mo, Nb, Ta and W; and the balance Ti, wherein said composition has a Mo equivalent value from about 6 to about 9. The work piece is preferably a medical device.

Abstract: A method for manufacturing a golf club with an improved durability which realizes so thin a club head that the head can be enlarged, suppressing the increase of the total weight. A cold rolled material, which is a beta type titanium alloy in a beta single phase and subjected to direct aging, is used for the head. Preferably, the material is subjected to at least 15% cold rolling reduction. The aging is able to improve durability and surface hardness. Due to the direct aging of the cold worked material without solution treatment, such a long time heat treatment is no longer necessary, thereby resulting in the reduction of production costs.

Abstract: The present invention relates to a method for-fabricating an integrally bladed rotor which comprises providing a hub section, preferably formed from a titanium based alloy, and welding an airfoil, also preferably formed from a titanium based alloy, to the hub section. The method further comprises partially aging and cooling the hub section prior to welding and aging the airfoil and the weld joint between the airfoil and the hub section subsequent to welding. The post welding aging step is preferably carried out using a novel encapsulated local airfoil heating device having a plurality of heating elements woven into a jacket made from a high temperature cloth material. The method of the present invention may also be used to repair integrally bladed rotors.

Abstract: In a blade possessing a blade body and a blade foot consisting of an alloy based on a doped gamma-titanium aluminide, at least part of the surface layer of the blade has a finely-grained structure, and the core has a coarsely-grained structure. The ductility of the finely-grained surface layer is higher than that of the coarsely-grained core. In a method for producing the blade, the surface is deformed after casting and hot-isostatic pressing of the blade. The deformed surface layer undergoes recrystallization annealing.

Abstract: Quenching a work piece made of a titanium alloy having a temperature higher than 800° C. to a temperature lower than 500° C. at a cooling rate greater than 10° C./second between 800° C. and 500° C. is used to render the cooled work piece containing &agr;″ phase as a major phase. The work piece is preferably a medical implant.

Abstract: A method of producing high purity, low oxygen content titanium powder utilizes a hydrided titanium powder crushed to desired percentage of particles of not more than a desired size. These hydrided particles are dehydrided by a slow heating process under partial vacuum to draw the hydrogen out of the particles with a minimum of sintering of the particles. The hydrided particles may be initially heated relatively rapidly, over a period of between about two hours and six hours to a temperature of between about 450° C. and 500° C. and then slowly over a period of four to five days to a temperature of between 650° C. and 700° C., all under a partial vacuum, until the hydrogen content of the powder reaches a desired value. The now dehydrided titanium powder is cooled, again crushed if and as necessary to break up any sintered particles, screened, and packaged. The method of the invention minimizes the sintering of the particles during the dehydriding process.

Abstract: A decorative titanium material according to the present invention eliminates a deterioration of the appearance even after processing, that is, provides a small surface roughness, and has a hardened layer of titanium at the surface of the titanium material, this hardened surface layer including nitrogen and oxygen, and having a surface crystal grain size in the range from 0.1 to 60 &mgr;m.

Abstract: A method for producing a forged striking plate for a golf club is disclosed herein. The forging process involves multiple heating and pressing of a metal bar to obtain a final face member configuration. The heating of the metal bar is performed at temperatures below 1000° C. for less than twenty minutes. The final face member configuration has a striking plate with regions of variable thickness. The metal bar is preferably composed of a forged titanium material.

Abstract: The invention relates to TiAl-base alloys with excellent oxidation resistance, and a method for producing the same. The TiAl-base alloy of the invention comprises a substrate and a surface part formed on the substrate, the surface part comprising at least one element of Cr, Nb, Ta and W and having a surface condition capable of forming a dense film of an oxide of the element or Al2O3 in high-temperature oxidizing atmospheres. The method of the invention comprises heating a TiAl-base alloy material having an Al content of from 15 at. % to 55 at. % in the presence of an oxide having a smaller negative value of standard free energy of formation than that of alumina. The method of the invention provides TiAl-base alloys with excellent oxidation resistance.

Abstract: A biocompatible titanium alloy with low modulus comprising &agr;″ phase as a major phase and containing from about 6 to about 9 wt % of molybdenum, from 0 to about 1 wt % of an alloying element and the balance titanium. The alloying element is niobium and/or zirconium. The biocompatible titanium alloy is suitable for use as a material for a medical prosthetic implant.

Abstract: The present invention provides a rolling bearing having an excellent corrosion resistance and toughness which can fairly operate at a high rotary speed. At least the inner race is formed by a titanium alloy, and the rolling elements are formed by ceramics. Alternatively, at least one of the inner race and the outer race is formed by a &bgr; type titanium alloy. The percent cold working of the &bgr; type titanium alloy is predetermined to not less than 20% or a range of from 5 to 20%. The cold working is followed by shot peening. Further, the surface hardness Hv is predetermined to not less than 600. The volumetric ratio of residual &bgr; phase in the &bgr; type titanium alloy is predetermined to a range of from 30 to 80%.

Abstract: A method is set forth for processing titanium and titanium alloys into titanium articles, in which the titanium exhibits enhanced ultrasonic inspection results for determining its acceptability in microstructurally sensitive titanium applications. The method for processing titanium comprises providing titanium at a temperature above its &bgr;-transus temperature; quenching the titanium from a temperature above the &bgr;-transus temperature, the step of quenching titanium forming an &agr;-plate microstructure in the titanium; and deforming the quenched titanium into a titanium article, the step of deforming the quenched titanium transforming the &agr;-plate microstructure into discontinuous &agr; particles without crystallization textures. The discontinuous-randomly textured &agr; particles lead to a reduction in ultrasonic noise during ultrasonic inspection.

Abstract: A process for producing a particle-reinforced titanium alloy includes the steps of: heating a titanium alloy in which ceramic particles having a thermodynamically stable property are dispersed in a temperature range of not less than &bgr;-transus temperature; and cooling the titanium alloy to pass through the &bgr;-transus temperature at a cooling rate of 0.1-30° C./second. The process can further include, before the heating step, the step of compressing the titanium alloy in a two phase temperature range of &agr;+&bgr; thereof or in a temperature range of not less than &bgr;-transus temperature.

Abstract: A method for chemically etching a forged striking plate for a golf club to uniformly remove 0.002 inch to 0.015 inch of material therefrom. The forged striking plate is placed in an acidic bath to uniformly remove material from all surfaces of the striking plate. The forging process, conducted prior to etching, involves multiple heating and pressing of a metal bar to obtain a final face member configuration. The heating of the metal bar is performed at temperatures below 1000° C. for less than twenty minutes. The final face member configuration has a striking plate with regions of variable thickness. The metal bar is preferably composed of a forged titanium material.

Abstract: A method for manufacturing an acoustic vibration plate includes molding titanium metal into a shape of an acoustic vibration plate in order to obtain a titanium vibration plate, and performing a heat treatment on the titanium vibration plate by a ceramic-formation step, thereby to change entirely the titanium vibration plate into titanium oxide.

Abstract: The invention produces mismatch plastic deformation in a workpiece by altering the chemical composition of the workpiece material, while the workpiece is subjected to a biasing stress, in a manner that introduces a strain increment into the material, deforming the workpiece without causing failure. In one approach, repeated cyclic alteration of chemical composition, so as to repeatedly alternately induce and reverse a phase transition that produces strain increment, allows accumulation of strain in an incremental fashion thereby achieving overall large, superplastic deformations in the workpiece without applying large stresses.

Abstract: A method of carburizing treatment is proposed in which if carburizing is carried out at a low temperature, carbon will not turn amorphose and deposit on the surface of a titanium metal but reliably penetrate into between metallic atoms. It is a method of surface treatment of a titanium metal comprising the steps of heating the titanium metal to a temperature of 400-690° C. in a cleaning gas atmosphere containing hydrogen gas, subjecting the surface of the titanium metal to cleaning by applying a DC voltage of 200-1500 V, and plasma carburizing in an atmosphere comprising a carburizing gas having the molar ratio of hydrogen atoms (H) to carbon atoms (C) adjusted to (H/C)≦9 at a pressure of 13-400 Pa and a temperature of 400-690° C. Ionization reaction in the gas is suppressed suitably. Because there exists no excessive carbon which is not used for carburization but turns soot or glass-like carbon, in the atmosphere during carburization, carburizing reaction progresses smoothly.

Abstract: The invention relates to TiAl-base alloys with excellent oxidation resistance, and a method for producing the same. The TiAl-base alloy of the invention comprises a substrate and a surface part formed on the substrate, the surface part comprising at least one element of Cr, Nb, Ta and W and having a surface condition capable of forming a dense film of an oxide of the element or Al2O3 in high-temperature oxidizing atmospheres. The method of the invention comprises heating a TiAl-base alloy material having an Al content of from 15 at. % to 55 at. % in the presence of an oxide having a smaller negative value of standard free energy of formation than that of alumina. The method of the invention provides TiAl-base alloys with excellent oxidation resistance. The TiAl-base alloys of the invention have significantly improved oxidation resistance and are resistant to heat at high temperatures of 900° C. or higher.

Abstract: A titanium layer is formed on a substrate with chemical vapor deposition (CVD). First, a seed layer is formed on the substrate by combining a first precursor with a reducing agent by CVD. Then, the titanium layer is formed on the substrate by combining a second precursor with the seed layer by CVD. The titanium layer is used to form contacts to active areas of substrate and for the formation of interlevel vias.

Abstract: A method has been developed to produce an attractive surface on titanium or titanium alloys. The material involves repeated thermal treatment in vacuum above the beta transformation temperature followed by cooling below this transformation temperature. This treatment produces an attractive large grained, speckled surface. The method can be applied to titanium sheet for construction purposes or to titanium or titanium alloy components in art, architecture, components for automotive trim and casing for cellular phones or computers.

Abstract: A corrosion-resistant Ti alloy includes Pd in an amount of 0.020-0.050 mass %, and includes one or more platinum group elements other than Pd in an amount of one-third or more of the mass of Pd, with the balance being composed of allowable components and Ti. This alloy exhibits excellent corrosion-resistance. If the Fe content is 0.05% or less and O content is 0.05% or less, excellent cold-workability can be obtained. If the Pd content is 0.030% or less, not only cold-workability and corrosion-resistance but also resistance against hydrogen absorption can be obtained.

Abstract: Described is a method for producing a diffusion bonded sputtering target assembly which is thermally treated to precipitation harden the backing plate without compromising the diffusion bond integrity. The method includes heat treating and quenching to alloy solution and artificially age the backing plate material after diffusion bonding to a target. Thermal treatment of the diffusion bonded sputtering target assembly includes quenching by partial-immersion in a quenchant and is performed after diffusion bonding and allows for various tempers in the backing plate.

Abstract: A Ti—V—Al based superelastic alloy wherein the proportions of Ti, Al and V, based on the total weight of the three components, fall within the range defined by the lines joining the following points of A, B, C and D shown in the ternary composition diagram of accompanying FIG. 1: A: 79.8% Ti, 17.5% V, 2.7% Al, B: 76.8% Ti, 20.5% V, 2.7% Al, C: 73.8% Ti, 20.5% V, 5.7% Al, D: 76.8% Ti, 17.5% V, 5.7% Al.

Abstract: A high strength and ductility &agr;+&bgr; type titanium alloy, comprising at least one is isomorphous &bgr; stabilizing element in a Mo equivalence of 2.0-4.5 mass %, at least one eutectic &bgr;stabilizing element in an Fe equivalence of 0.3-2.0 mass %, Si in an amount of 0.1-1.5 mass %, and C in an amount of 0.01-0.15% mass, and has a &bgr; transformation temperature no lower than 940° C.

Abstract: A Ti—Ni shape memory alloy with ductility, including Ti of 50˜66 atomic % in a composition, and in which precipitation of TI2Ni phases at grain boundaries is suppressed.

Abstract: A monolithic refractory depositing system capable of improving working environment and working efficiency and of spraying a material in a uniform thickness is provided. The monolithic refractory depositing system is capable of carrying out both a spraying process and a casting process.

Abstract: A method for treating metal workpieces, including non-ferrous metal workpieces such as Titanium. The metal workpieces are heat soaked for a predetermined amount of time in a furnace at a predetermined temperature. An interstitial element is introduced into the area adjacent to the surface of the metal workpieces until a predetermined concentration of the interstitial element exists in the area adjacent to the metal workpieces. The treated metal workpieces are then cooled, resulting in the metal workpieces having a diffusion region formed which extends into the body of the metal workpieces. The region has a gradient of the interstitial element formed therein.

Abstract: A high strength and ductility &agr;+&bgr; type titanium alloy, comprising at least one isomorphous &bgr; stabilizing element in a Mo equivalence of 2.0-4.5 mass %, at least one eutectic &bgr; stabilizing element in an Fe equivalence of 0.3-2.0 mass %, and Si in an amount of 0.1-1.5 mass %, and optionally comprising C in an amount of 0.01-0.15 % mass.

Abstract: To be able to satisfactorily bright-anneal metals having a high affinity to oxygen in a hood-type furnace or the like under a protective gas, a rather pure inert gas such as argon, neon or helium, which is mixed with not more than 50 vol-% of a reducing gas, for instance hydrogen, is used as protective gas in cooperation with an oxygen binder, preferably titanium.

Abstract: Titanium aluminide for precision casting, having the following chemical composition: Al: 31.3 to 32.0 wt %, Fe: 0.5 to 1.0 wt %, V: 1.0 to 1.5 wt %, and B: 0.03 to 0.06 wt %, with the remainder being Ti and inevitable impurities. A melt of this titanium aluminide is powered into a die and cooled at a general speed. A cast will have a fully lamellar structure almost entirely in an as-cast condition. This titanium aluminide does not have precipitation of &bgr;2 phase in a colony grain boundary of the lamellar structure. It is therefore possible to obtain a higher degree of grain boundary serration in the as-cast condition. As a result, the titanium aluminide product has an excellent creep property.

Abstract: A titanium aluminide having the following chemical composition:Al: 33.5-34.5 wt %,Fe: 1.5-2.0 wt %,V: 1.5-2.0 wt %, andB: 0.05-0.10 wt %, with the remainder being Ti and inevitable impurities. Greatly decreased is a ratio of .alpha..sub.2 phase (Ti.sub.3 Al) precipitatable in a TiAl matrix. Accordingly, it is possible to deposit a trace amount (2-5%) of thin line-like .alpha..sub.2 phase in the TiAl matrix. This titanium aluminide is particularly suitable for precision casting.

Abstract: A hydrogen-absorbing alloy capable of controlling the very fine structure formed by a spinodal decomposition for improving flatness of an emission equilibrium pressure in a practical temperature/pressure range and excellent in activation and hydrogen absorption/desorption amounts, and a production method thereof. The hydrogen-absorbing alloy has a composition expressed by the general formula Ti.sub.x Cr.sub.y V.sub.z (where each of x, y and z represents an atomic percent and satisfies the relation x+y+z=100), wherein the composition has a body-centered cubic structural phase as a principal phase, the principal phase exists within the range in which the body-centered cubic structure appears and a spinodal decomposition occurs with the exception of a C14 (a typical structure of the Laves phase; a MgZn.sub.2 type crystal structure) mono-phase range, and has a regular periodical structure formed by the spinodal decomposition, and its apparent lattice constant is at least 0.2950 nm but is not greater than 0.

Abstract: Modern brake rotors require enhanced resistance to thermal stress in order to withstand vigorous operating conditions. A brake rotor manufactured from (.alpha.+.beta.) titanium alloy will fulfill the thermal stress requirements when an equiaxed grain structure is imposed on the alloy. The equiaxed grains can preferably range from 300 .mu.m to 3 mm in size. The equiaxed grain structure is attained by heat treating the brake rotor at the .beta. phase transformation temperature, followed by quenching. When Ti-6Al-4V titanium alloy is used to form the brake rotor, .beta. phase transformation temperature is 1000.degree. C. the heat treatment temperature range is 986-1200.degree. C. The preferable heat treatment for Ti-6Al-4V alloy is 1050.degree. C. for 2 hours.

Abstract: A method for producing titanium alloy turbine blades comprising the steps of (a) forming turbine blades of titanium alloy through hot forging or machining, (b) cooling leading edges on tip portions of the turbine blades including covers thereof formed through hot forging or machining faster than blade main body after final hot forging or solid solution treatment, and (c) heat treating the cooled turbine blades. With this method, it is possible to manufacture titanium turbine blades in an economical fashion and obtain titanium alloy turbine blades superior in reliability by preventing erosion.

Abstract: Monolithic metal oxide structures, and processes for making such structures, are disclosed. The structures are obtained by heating a metal-containing structure having a plurality of surfaces in close proximity to one another in an oxidative atmosphere at a temperature below the melting point of the metal while maintaining the close proximity of the metal surfaces. Exemplary structures of the invention include open-celled and closed-cell monolithic metal oxide structures comprising a plurality of adjacent bonded corrugated and/or flat layers, and metal oxide filters obtained from a plurality of metal filaments oxidized in close proximity to one another.

Abstract: A high strength, high ductility titanium alloy comprising O, N and Fe as strengthening elements and the balance substantially Ti, the contents of the strengthening elements satisfying the following relationships (1) to (3):(1) from 0.9 to 2.3% by weight of Fe,(2) up to 0.05% by weight of N, and(3) an oxygen equivalent value Q, which is defined by the formula mentioned below, of 0.34 to 1.00Q=[O]+2.77[N]+0.1[Fe]wherein [O] is an oxygen content (% by weight), [N] is a nitrogen content (% by weight) and [Fe] is an iron content (% by weight), the titanium alloy having a tensile strength of at least 700 MPa and an elongation of at least 15%. Part of Fe may be replaced with Cr and/or Ni. Fe, Cr and Ni may be introduced from a carbon steel or stainless steel, or they may be introduced from sponge titanium containing these elements.

Abstract: The invention produces superplastic deformation in a workpiece by altering the chemical composition of the workpiece material, while the workpiece is subjected to a biasing stress, in a manner that introduces a strain increment into the material that effects a change in a overall dimension of the workpiece without causing failure. In one approach, repeated cyclic alteration of chemical composition, so as to repeatedly alternately induce and reverse a phase transition that produces strain increment, allows accumulation of strain in an incremental fashion thereby achieving large overall superplastic deformations in the workpiece without applying large stresses.

Abstract: A process of preparing a titanium-tantalum alloy including forming a suite mixture of essentially pure titanium powder and essentially pure tantalum powder, melting the mixture of titanium powder and tantalum powder by plasma torch melting under a pressure greater than atmospheric pressure to form a titanium-tantalum solution, and casting the molten solution of titanium-tantalum to form a solid homogeneous titanium-tantalum product is disclosed.The process can further include hot-rolling the cast solid homogeneous titanium-tantalum product to form a sheet of the titanium-tantalum product.

Abstract: Described is a titanium sputtering target to provide improved step coverage and a method of making same.

Abstract: Surface-treating metallic parts are produced by applying mechanical energy to the surface of a metallic part and to a substance on or near the surface of the metallic part. The substance is different from the metallic part in composition. The applying step forms a mechanically-alloyed layer from the metallic part and the substance in the surface of the metallic part. The surface-modified layer such as the mechanically-alloyed layer is a non-peeling alloyed layer having a composition or structure different from that of the metallic part. The method is effective in surface-treating light metal materials of which the surfaces are difficult to treat. For example, the method is applicable to soft Mg alloys and Al alloys to improve their surface hardness, and the thus-treated alloys are usable in slide parts which are required to have good wear resistance.

Abstract: A TiAl intermetallic compound-base alloy material having excellent strength properties at high temperatures and ductility, characterized by comprising: a fine alumina (Al.sub.2 O.sub.3) dispersed so as to give an O.sub.2 concentration of 1000 to 5000 ppm by weight and in a particle diameter of 200 to 500 nm; a boride (TiB.sub.2) dispersed to give a B concentration of 0.1 to 10 at % and in a particle diameter of not more than 500 nm; 1 to 3 at % of at least one of Cr, Mn, and V; and TiAl having a Ti content of 50 to 53 at % and an Al content of 47 to 50 at %, said TiAl intermetallic compound-base alloy material having been directly cast at a cooling rate of 10.sup.3 to 10.sup.5 .degree. C./sec and a process for producing the same. According to the present invention, exhaust valves for automobiles and materials for engine turbines for jet airplanes and the like having excellent tensile strength at high temperatures and ductility at high temperatures and room temperature are provided.

Abstract: This invention is a Titanium Aluminum alloy consisting essentially of the formula in atomic percent; Ti.sub.Bal. Al.sub.45-48 B.sub.0.01-0.75 Cr.sub.0-2 W .sub.0.25-2.25 Si.sub.0.1-0.7. The Boron is present in an atom. % of 0.01-0.75. The desired range is 0.1-0.5. The preferred range is 0.25+/-0.05. The optimum range is 0.25. The Chromium is present in an atom. % of 0-2. The desired range is 1.3-1.6. The preferred range is 1.5+/-0.1. The optimum range is 1.5. The Tungsten is present in an atom. % of 0.25-2.25. The desired range is 0.3-2.11. The preferred range is 0.75+/-0.05. The optimum range is 0.75. The Silicon is present in an atom. % of 0.1-0.7. The desired range is 0.4-0.6. The preferred range is 0.5+/-0.05. The optimum range is 0.5. The atom. % ratio of Cr/W is 0-5. The desired range is 1.33-2.69. The preferred range is 1.8-2.6. The optimum range is 1.85-2.5. The preferred alloy is a Titanium Aluminum alloy consisting essentially of the formula in atomic percent; Ti.sub.Bal. Al.sub.45.82 B.sub.0.25 Cr.

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 mixed oxide ceramic product is made directly from a metal alloy of titanium, zirconium and/or hafnium and niobium, tantalum or hafnium, where the normally combustible alloy of titanium and zirconium or hafnium is passivated by the addition of more than about 7 atomic percent of niobium and/or tantalum and or vanadium which alloy can then be heated in air at atmospheric pressure to a temperature of from about 800 degrees C. to about 1500 degrees C. to produce an adherent monolithic ceramic containing product.

Abstract: A process for enhancing the bond strength of resistance welded joints between titanium alloy articles includes a first step of resistance welding two titanium alloy articles and a second step of heat treating the resistance welded titanium alloy articles in a vacuum or inert environment at temperatures in a range of 1675.degree. F. to 1825.degree. F. for a period of 15 minutes to 4 hours. The process of the present invention is particularly useful in providing efficient joining of face sheets to a honecomb core element.

Abstract: Additions of a first alloy constituent of at least one element from the group consisting of Y, Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, or any combinations of them, and a second alloy constituent of at least one element from the group consisting of C, Si, Ge, Sn and Pb, or any combinations of them, to Ti-base alloys can be employed so as to result in an alloy containing an very fine, substantially homogeneous oxide dispersoid of the first constituent, and produce alloys having improved tensile properties, especially tensile elongation. The dispersoid results from the decomposition of an intermediate phase dispersoid comprising a compound of the first and second constituents which results from rapid solidification of the alloy from a melt. It is preferred that the second alloy constituent should be at a concentration sufficient to form the intermediate phase with all of the element or elements comprising the first alloy constituent.

Abstract: Controllable oxidation of certain titanium zirconium alloys is achieved by utilizing minor proportions of niobium, tantalum or vanadium or mixtures thereof and articles formed therefrom can be partially oxidized to form a deep, hard monolithic oxide containing surface layer and further or completely oxidized to form a cermet or ceramic body respectively, which can be heated further to improve the ceramic bodies properties.

Abstract: A method of manufacturing a blade made of .alpha..beta. titanium including an insert of metastable .beta. titanium,according to the invention:a blade body made of .alpha..beta. titanium is made to the finished design dimensions, said blade body made of .alpha..beta. titanium including a location designed to receive said insert made of .beta. titanium:said insert made of .beta. titanium is put into solution; thenhardening treatment is performed to harden said insert made of .beta. titanium; thensaid insert made of .beta. titanium is welded to said location of said blade body made of .alpha..beta. titanium to the finished design dimensions using a welding technique having localized and controlled energy density.

Abstract: An article made of a gamma titanium aluminide alloy is welded, as for example in the weld repair of surface cracks, by removing foreign matter from the area to be welded, first stress relieving the article, cooling the entire article to a welding temperature of from about 1000.degree. F. to about 1400.degree. F., welding a preselected region in an inert atmosphere at the welding temperature, and second stress relieving the article. Welding is preferably accomplished by striking an arc in the preselected region so as to locally melt the alloy in the preselected region, providing a filler metal having the same composition as the gamma titanium aluminide alloy of the article, and feeding the filler metal into the arc so that the filler metal is melted and fused with the article to form a weldment upon solidification.

Abstract: Methods are presented to produce duplex (DP) microstructures, nearly lamellar (NL) microstructures, and fully TMT lamellar (TMTL) microstructures in gamma titanium aluminide alloy articles. The key step for obtaining a specific type of microstructure is the post-hot work annealing treatment at a temperature in a specific range for the desired microstructure. The annealing temperatures range from Te+100° C. to T&agr;−25° C. for duplex (DP) microstructures, from T&agr;−25° C. to T&agr;−5° C. for nearly lamellar (NL) microstructures, and from T&agr; to T&agr;+60° C. for fully TMT lamellar (TMTL) microstructures, where Te is the titanium-aluminum eutectoid temperature of the alloy and T&agr; is the alpha transus temperature of the alloy. The times required for producing specific microstructures range from 2 min to 15 hours depending on microstructural type, alloy composition, annealing temperature selected, material section size, and desired grain-size.