Microscopic phase-field simulation of coarsening behavior of precipitates in Ni₇₅Al_xV_25-x alloy

Based on the microelasticity theory of coherent strain and the microscopic phase-field dynamic model, the morphology evolution and the coarsening behavior of precipitates in Ni₇₅Al_xV_25-x alloy were simulated. The two precipitate particles have the obvious orientation when the coarsening happened. The [100] direction of θ phase (Ni₃V) is the preferential growth direction and γ′ phase (Ni₃Al) aligned along the <001> directions. The precipitated sequence of the two phases is related to Al content. The growth and coarsening of the early precipitated phase have two evident stages, but growth and coarsening of the late precipitated phase evolved simultaneously. The growth and coarsening of precipitates take place by means of the coalescence between neighboring particles. In despite of the precipitated sequence and the volume fraction are different for the alloys with different concentrations, the morphologies of two phases are almost same at last, which have the quadrate shape, and the orientation relationship of (001)_θ//{100}_γ′ exists between two phases.