Applied Strain Field on Microstructure Optimization of Ti-Al-Nb Alloy Computer Simulated by Phase Field Approach

The effects of applied tensile strain on the coherent α2→O-phase transformation in Ti-Al-Nb alloys are explored by computer simulation using a phase-field method. The focus is on the influence of the applied strain direction on the microstructure and volume fraction of the O-phase precipitates. It is found that altering applied strain direction can modify microstructure of Ti-25Al-10～12Nb (at. Pct) alloy during α2→O-phase transformation effectively and full laminate microstructure in the Ti-25Al-10Nb (at. Pct) alloy can be realized by an applied strain only along the direction 30° away from the α2 phase <1010> in magnitude equivalent to the stress-free transformation strain. The simulation also shows that not only the magnitude of applied strain but also the applied strain direction influences the O-phase volume fraction and the effect of strain direction on the volume fraction is up to 25%.