TITANIUM-ALUMINUM BASE INTERMETALLIC COMPOUND ALLOY CONTAINING W AND EXCELLENT IN SUPERPLASTIC CHARACTERISTIC AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To produce a TiAl base intermetallic compound provided with excellent superplastic deformability as well by adding a specified amt. of W to a lightweight TiAl base intermetallic compound excellent in high temp. strength and executing high temp. thermomechanical treatment under specified conditions. SOLUTION: A master alloy of Ti and W is added to the molten metal of a TiAl intermetallic compound, and the intermetallic compound having a compsn. expressed by Tia Al100-a-b Wb is melted [(a) and (b) in the compositional formula respectively satisfy 46at%<=(a)at%<=56at% and 0.5at%<=(b)at%<=5at% and 2(a)at%+(b)at%=100]. The ingot of this intermetallic compound is subjected to homogenizing heat treatment, is thereafter subjected to hot working in a nonoxidizing atmosphere and is cooled to the one between specified temps. Its structure is formed into theγ+βfine two phase one usingγphases as the matrix and in whichβphases are precipitated over the grain boundaries. Superplastic characteristics are imparted to the conventional low workability TiAl intermetallic compound alloy poor in deformability at a room temp. or above, and it can easily be worked into a final shape with high precision.