Numerical Study of Elastic Effects by Cubic-Tetragonal Symmetry Breaking on the Ordering Kinetics

Elastic effects by cubic-tetragonal symmetry breaking on the ordering kinetics are investigated. We propose a coarse-grained model characterized by a Ginzburg-Landau free energy with non-conserved order parameters coupled to an elastic field. By numerical study we obtain an oval shaped domain and a square domain in two dimensions and a plate-like domain and a rod-like domain in three dimensions. And in the coarsening process, a striped pattern is obtained. These patterns are remarkably similar to morphologies observed in real cubic-tetragonal order-disorder alloys. Moreover, we study the dynamics during the coarsening process by analyzing the change of the total domain boundaries L_DB(t). L_DB(t) decreases as a power of time: t^-α(α > 0). The exponent a becomes small with increasing the magnitude of the elastic effects.