Precipitation kinetics of γ phase in an inverse Ni-Al alloy

The precipitation kinetics of γ phase in the inverse Ni-20.4 at. % Al alloy are studied by utilizing phase-field method, combining with the volume fraction, particles number density, average particle radius, average aspect ratio and particle size distribution (PSD) of γ phase at different aging temperatures. It is found that the decrease rate of particles number density increases with the elevated aging temperature, and the decrease rate in the early coarsening stage are greater than that in the stable coarsening stage. The average particle radius shows a linear relationship with time through kt1/3 in the stable coarsening stage of the inverse Ni-Al alloy, and the coarsening rate constant k increases with the elevated temperature. As the aging progresses, the peak value of PSD becomes smaller and the normalized radius r/ moves from 1.1 to 1.0, while the peak value of PSD becomes larger and the corresponding r/ value moves from 0.9 to 1.0 with the elevated temperature. The peak value of PSD is less than that predicted by Lifshitz-Slyozov-Wagner (LSW) theory at different aging temperatures.