Effect of Heat Treatment on Microstructures and Properties of Near-Isothermally Forged TiAl Alloy Containing Minor Ni

摘要

The heat treatment, including two steps, was proposed to obtain Fine Fully Lamellar (FFL) microstructure on TiAl containing minor Ni. The first step was in (α+γ) phase region to get Duplex (DP) microstructure, and the second step was in α phase region transforming DP microstructure into FFL microstructure. The effect of heat treatment on microstructures and properties was studied. The results showed that the static recrystallization kinetics in (α+γ) phase region took the form of Avrami equitation, and the remnant lamellae in DP microstructure were detrimental to room temperature tensile properties. The FL microstructures were obtained after heat treatment in α phase region using DP microstructure, the uniform FFL microstructure was beneficial to comprehensive properties.