Phase-field simulation of domain structure evolution during a coherent hexagonal-to-orthorhombic transformation

摘要

The formation and temporal evolution of domain structures during a hexagonal --> orthorhombic transformation is studied using computer simulations based on a continuum diffuse-interface phase-field approach. All the essential driving forces for the domain formation and evolution an taken into account, including the bulk chemical free energy, the domain wall energy and the elastic strain energy. The various domain configurations observed from the computer simulations show excellent agreement with existing experimental observations in a number of systems undergoing hexagonal --> orthorhombic or hexagonal --> monoclinic transformations. It is shown that, even with the assumption of isotropic domain wall energy and isotropic elastic modulus, the anisotropic elastic interactions alone caused by the non-dilatational strains can reproduce ail the interesting domain structures observed experimentally. It is also demonstrated that many of the specific domain configurations are actually formed during the domain coarsening process after the phase transformation has been completed. [References: 32]