γ→β phase transformation in Ti-42.9Al-4.6Nb–2Cr

This paper investigates the γ→β phase transformation in a β-solidifying γ-TiAl alloy (Ti-42.9Al-4.6Nb–2Cr, at. %), by means of SEM and TEM. The results show that part of β/γ phase interface is flat, and TEM observations reveal that stacking faults pairs sometimes act as the β/γ phase interface in isothermally compressed samples. The γ→β phase transformation was a diffusional process, and was mainly governed by diffusion of Ti, Al and Cr. The occurrence of stacking faults pairs during γ→β phase transformation at the β/γ phase interface was related to low SISF energy and sluggish Nb diffusion.