TDGL computer simulation of order-disorder phase transformation

The phase transformation process has been investigated by using the time dependent Ginzburg-Landau (TDGL) model with conservative and non-conservative variables. The Ginzburg-Landau type free energy contains a term of \xi3 in order to describe a first kind of transition, where \xi is the order-parameter. The kinetic equations were formulated with the composition and the order-parameter which are the conservative and the non-conservative variables, respectively. The changes in microstructure were simulated by using the, kinetic equations, and they were found to be in good coincidence with those in Cu3Pt observed with a transmissiona electron microscope. The simulation revealed that the degree of order averaged over the system changes with the annealing time in a different way depending on the annealing temperature. The changes in the degree of order can be divided into several processes which are strongly related to the behaviors of APBs