A process for producing a workpiece from an alloy containing dopant and based on titanium aluminide. The process is intended to produce a workpiece of high oxidation and corrosion resistance, good high-temperature strength and adequate ductility. The process steps include melting the alloy, casting the melt to produce a cast body, cooling the cast body to room temperature and removing its casting skin and its scale layer. The descaled cast body is subjected to high-temperature isostatic pressing at a temperature between 1200° and 1300° C. and a pressure between 100 and 150 MPa, and cooling the isostatically pressed cast body. The cooled cast body is heated to temperatures of 1050° to 1200° C., deformed isothermally one or more times at this temperature for the purpose of molding and structure improvement, and cooled to room temperature. The deformed cast body is machined to produce a workpiece by material removal.

Process for producing a workpiece from an alloy containing dopant and based on titanium aluminide

A novel titanium base alloy having a micrograph with alpha plates oriented in three directions with respect to their parent beta grains, but with alpha plates so short that no basketweave pattern is evident. The alloy contains from 0.02 to 2.0 atomic percent boron; 6 to 30 atomic percent aluminum; 0 to 4 atomic percent tin; 0 to 4 atomic percent gallium; and may contain 0 to 6 atomic percent zirconium or hafnium or a mixture of the two; 0 to 12 atomic percent of at least one metal selected from the group consisting of vanadium, columbium, tantalum, chromium, molybdenum, rhenium, tungsten, ruthenium, and the platinum group metals; and from 0 to 2 atomic percent of at least one element selected from the group consisting of yttrium, carbon and the rare earth metals.

Method of modifying multicomponent titanium alloys and alloy produced

OF THE DISCLOSURE The turbine blade contains a casting having a blade leaf (1), blade foot (2) and, if appropriate, blade cover strip (3) and composed of an alloy based on a dopant-containing gamma-titanium aluminide. This turbine blade is to be distinguished by a long lifetime, when used in a turbine operated at medium and high temperatures, and, at the same time, be capable of being produced in a simple way suitable for mass production. This is achieved in that, at least in parts of the blade leaf (1), the alloy is in the form of a material of coarse-grained structure and with a texture resulting in high tensile and creep strength and, at least in parts of the blade foot (2) and/or of the blade cover strip (3), provided if appropriate, is in the form of a material of fine-grained structure and with a ductility increased in relation to the material contained in the blade leaf (1). (single figure)

Turbine blade and process for producing this turbine blade

A turbine rotor consisting of a wheel made of a TiAl alloy of good heat resistance and a rotor shaft made of a steel with good bonding strength is disclosed. As the shaft material a structural steel or a martensitic heat resistant steel is used. A TiAl turbine wheel made by precision casting is butted to the shaft with insertion of a brazing filler in the butted interfaces and stress of 0.01 kgf/mm2 or higher but lower than yield stress of the shaft is applied on the butted interfaces under heating by high frequency induction heating in atmosphere of an inert gas or a reducing gas to a temperature higher than the liquidus temperature of the brazing metal but not exceeding 100° C. above the liquidus temperature. Turbine rotors with good accordance of the axes of the wheel and the shaft will be obtained by fitting a projection (or recess) and a recess (or projection) formed at the base of the wheel and the end of the shaft concentrically to the outer shape thereof, and by brazing the ring-shaped area outside the fitted parts.

TiAl turbine rotor and method of manufacturing

Disclosed is a method of forming a joint between a Ti-Al alloy member (1A) which consists mainly of an intermetallic compound TiAl, and a steel structural member (3). The method uses an intermediate member (2A, 2B) made of an austenitic stainless steel or a heat resistant steel, or a Ni-based or Co-based super-alloy, between the above two members, and the intermediate member and the steel structural member are friction welded together. The resultant jointed machine parts find utility in engine valves.

Method of forming a joint between a Ti-Al alloy member and a steel structural member

Disclosed are Ti-Al alloys having increased ductility and Ti-Al alloys having increased ductility and lowered melting points, in both of which the main constituent phase is an intermetallic compound, TiAl. The Ti-Al alloys having increased ductility essentially consisting of Al: 28-38%, and B: 0.005-0.3%, the balance being Ti and inevitable impurities. Since the alloys of this type have good proces­sability, they are suitable as materials for mechanical parts of rotating or reciprocating systems, where high heat-resistance and high specific strength are required. The Ti-Al alloys having increased ductility as well as lowered melting points essentially consisting of Al: 28-38%, one or two of Ni: 0.05-3.0% and Si: 0.05-3.0%, and the balance being Ti and inevitable impurities. Optionally, this alloy further contains B: 0.005-0.3%. The alloy of this type is, in addition to the above use, suitable for producing machine parts made by precision casting technology.

Titanium-aluminium alloy

Disclosed are Ti-Al alloys having increased ductility and Ti-Al alloys having increased ductility and lowered melting points, in both of which the main constituent phase is an intermetallic compound, TiAl. The Ti-Al alloys having increased ductility essentially consisting of Al: 28-38%, and B: 0.005-0.3%, the balance being Ti and inevitable impurities. Since the alloys of this type have good processability, they are suitable as materials for mechanical parts of rotating or reciprocating systems, where high heat-resistance and high specific strength are required. The Ti-Al alloys having increased ductility as well as lowered melting points essentially consisting of Al: 28-38%, one or two of Ni: 0.05-3.0% and Si: 0.05-3.0%, and the balance being Ti and inevitable impurities. Optionally, this alloy further contains B: 0.005-0.3%. The alloy of this type is, in addition to the above use, suitable for producing machine parts made by precision casting technology.

Takuya Miyashita

Papers

Titanium-aluminium alloy

Ti-Al intermetallics containing boron for enhanced ductility