Phase-field simulation of martensitic transformation with different conditions in inhomogeneous polycrystals

The microstructure evolution of Ti64 has been simulated to investigate the effect of different factors on the martensitic transformation (MT) in an elastically homogeneous system within a single parent grain by many researchers. In the present case the MT in a polycrystalline aggregate is considered taking into consideration the inhomogeneous elasticity of different orientations. In the present work, the phase-field modelling (PFM) is employed to study the microstructure evolution of nucleation and growth in different conditions during MT for Ti-6A1-4 V polycrystalline alloy in two dimensions, including external tension/compression loading, with and without plastic deformation and strain hardening. Results indicate that the grain boundaries are the prior sites for nucleation of martensite plates, and the external loading and plastic deformation can influence the micro-structure to a large degree. It can be concluded that the change of elastic strain and stress in the simulated system, including the applied loading, strain relaxation at grain boundaries and plastic deformation are important features during MT. The martensitic product structure can be predicted with the current poly-crystalline phase field model.