Microstructure evolution of a forged TiAl-Nb alloy during high-temperature tensile testing

Abstract

A forged TiAl-Nb alloy was investigated by means of measurements of properties related to performance at high temperatures, and the microstructure was observed by scanning electron microscopy (SEM) with electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM). The brittle-ductile transition temperature of the alloy was between 800 °C and 820 °C. The alloy had high strength in the brittle stage, and the main deformation mechanisms of the alloy were dislocation movement and dynamic recovery (DRV) in the γ phase. In the ductile stage, the alloy had good deformation ability and the main deformation mechanism of the alloy was continuous dynamic recrystallization (CDRX) in γ phase and α2 phase, the integrity of the lamellar colonies was destroyed. At the same time, the phase transformation occurred.