Deformation-induced γ↔α2 phase transformation in TiAl alloy compressed at room temperature

Deformation-induced gamma alpha(2) phase transformation in a Ti-47Al-2Cr-2Nb-0.2Y (at.%) alloy compressed at room temperature was investigated by high-resolution transmission electron microscopy (HREM) and energy dispersive spectrum (EDS). The deformation-induced (DI) gamma -> alpha(2) phase transformation occurred in a twin intersection region. On the other hand, the deformation-induced alpha(2) -> gamma transformation nucleated at the stacking faults of alpha(2), phase. The composition analysis of the gamma and alpha(2) laths by EDS suggested that composition of some laths deviated much from their equilibrium values. These composition deviations promoted the deformation-induced gamma alpha(2) phase transformation to occur; EDS results also suggested that there was no composition difference between the DI-gamma plate and the primary gamma phase. Based on the HREM and EDS experimental results, the mechanism of the deformation-induced gamma alpha(2) phase transformation has been discussed. (c) 2006 Elsevier Ltd. All rights reserved.