Microstructural simulation in spinodally-decomposed Cu–70 at.%Ni and Cu–46 at.%Ni–4 at.%Fe alloys

The microstructure simulation of spinodal decomposition was carried out in the isothermally-aged Cu–70at.%Ni and Cu–46at.%Ni–4at.%Fe alloys using the phase field method. The numerical simulation was based on the solution of the Cahn–Hilliard nonlinear partial differential equation by the explicit finite difference method. A slow growth kinetics of phase decomposition was observed to occur in the aged Cu–Ni alloy. The morphology of decomposed phases consisted of an irregular shape with no preferential alignment in any crystallographic direction at the early stages of aging in this alloy. The growth kinetics rate of phase decomposition in the aged Cu–46 at.%Ni–4 at.%Fe alloy was appreciably faster than that in the aged Cu–70 at.%Ni alloy. In the case of the aged Cu–46 at.%Ni–4 at.%Fe alloy, an irregular shape of the decomposed phases was also observed at the early stages of aging. A further aging caused the change of initial morphology to a cuboid and/or plate shape of the decomposed Ni-rich phase aligned in the elastically-softest crystallographic direction <100> of Cu-rich matrix.