Computer-aided studies on the phase decomposition based on the non-linear diffusion equation.

Abstract

General forms of Fourier expressions for the one- and two-dimensional non-linear dif fusion equations containing the gradient energy term are proposed and computer-simulations in some supersaturated solid solutions are derived on the basis of the Fourier expressions. The phase-decompositions proceed to form periodic zone-arrangements in the high solute alloys, while in the low solute alloys a few composition peaks sparsely distributed appear. In the calculation for the phase decomposition of an elastically anisotropic solid solution, the modulated structure is formed, which explains well the morphology in actual spinodally decomposed alloys having an elastic anisotropy factor greater than unity. The computer simulations obtained based on the non-linear diffusion equations are very useful and powerful for the basic understanding of phase decomposition.