Kinetics of cubic to tetragonal transformation under external field by the time-dependent Ginzburg-Landau approach

Computer simulations based on the time-dependent Ginzbug-Landau approach have been performed for the formation of domain structure in the cubic-tetragonal transformation under an external field. The fcc-L1(0) ordering has been studied as a model case of the transformation, and the Landau free-energy function has been determined so as to reproduce the free energy calculated by the Monte Carlo simulation. The simulations have demonstrated the features observed in our experiments on FePd alloy under an external stress, and have clarified the formation mechanism of a single variant structure. The internal stress field developed by the preferential formation of a variant favored by the external stress further accelerates the trend cooperatively, and eventually leads to a single variant structure.