Simulation of hexagonal–orthorhombic phase transformation in polycrystals

Abstract The microstructural evolution during hexagonal–orthorhombic (HO) phase transformation in polycrystals was modeled by means of a modeling technique combining the strain-only theory and phase-field modeling. Specifically, the strain-only theory is used to describe the HO transformation, whereas phase-field modeling is employed to capture the evolution of the grain orientation in polycrystals. The modeling appropriately describes important aspects of the HO transformation behavior of polycrystals, such as the phase transition sequence, the lamellar-like twins in two orthogonal directions, streamers and striated variants. Furthermore, it predicts the accommodation of the HO polycrystal, in which the domain morphologies are rearranged in distinct manners for variously oriented grains as a response to uniaxial loading, thereby demonstrating the fact that the morphological evolution in polycrystals is a correlated collective process.