Influence of an applied strain field on microstructural evolution during the alpha(2) -> O-phase transformation in Ti-Al-Nb system

We investigate the influence of an applied homogeneous strain on the cohere nt alpha (2) (DO19) to O-phase transformation in Ti-Al-Nb alloys using a ph ase-field approach. The emphasis is on the effect of the applied strain on the two-phase morphology, as well as the equilibrium volume fractions of di fferent orientation domains of the O-phase. It is found that the applied ho mogeneous strain field does not change the essential features of the morpho logical patterns, but does alter the relative amount of each orientation do main and the equilibrium volume fraction of the O-phase. When the applied s train is of the same order of magnitude as the stress-free transformation s train, the initial two-phase mixture becomes unstable and transforms into a single O-phase. (C) 2001 Acta Materialia Inc. Published by Elsevier Scienc e Ltd. All rights reserved.