Lamellar orientation control in TiAl base alloys by a two-step compression process at high temperature

Abstract

In order to arrange the lamellar plates of a fully lamellar TiAl base alloy, high temperature compression in the α single-phase region and (α + γ) two-phase region was applied. The occurrence of dynamic recrystallization (DRX) and the formation of fiber texture were observed by compression in the α single-phase region. The maximum pole density of the compression axis was in a direction about 35° away from the ( 0 0 0 1 ) α 2 plane normal. Texture developed with decreasing true strain rate. This is because DRX proceeds mainly through a strain-induced grain boundary migration mechanism at low Zener–Hollomon parameter deformation conditions. Under compression in the (α + γ) two-phase region, softening was observed through compression. This can be attributed to the occurrence of geometrical softening and DRX. The lamellar interface became almost parallel to the compression plane after compression in the (α + γ) two-phase region.