γ-Phase transformation, dynamic recrystallization and texture of a forged TiAl-based alloy based on plane strain compression at elevated temperature

Abstract

In order to investigate the real or close-to-real high temperature microstructures of a TiAl-based alloy during rolling, low-cost plane strain compression tests were carried out at elevated temperature. γ as a dominant and plastic phase was selected as the main research object. It was found that fine γ lamellae precipitated in α2 phase deformed at 1200°C, with a total engineering strain of 60%. The precipitation of γ lamellae was mainly attributed to deformation-induced phase transformation at high temperature. Additionally, a certain misorientation angle (~89°) was observed in γ phase of all the samples and related to discontinuous dynamic recrystallization. Discontinuous dynamic recrystallization was promoted by pseudo and true twin boundaries which increased with increasing temperature and total strain. As regards γ-phase textures, the cubic textures related to recrystallization seemed to be readily weakened because of the γ→α2 and α2→γlamella transformations, while R texture was not significantly influenced. In addition, the cubic components and R component were respectively weakened and enhanced with increasing temperature and total strain. In short, enhancing or weakening of textures was mainly associated with phase transformation and recrystallization which were operated by deformation conditions.