Phase-field study on competition precipitation process of Ni-Al-V alloy

With microscopic phase-field kinetic model, atomic-scale computer simulation program for the precipitation sequence and microstructure evolution of the ordered intermetallic compound γ' and θ in ternary Ni75AlxV25-x alloy were studied. The simulation results show that Al concentration has important effects on the precipitation sequence. When Al concentration in Ni75AlxV25-x alloy is low, θ(Ni3V) ordered phase will be firstly precipitated, followed by γ'(Ni3Al) ordered phase. With Al concentration increasing, θ and γ' ordered phases are simultaneously precipitated. With Al concentration further increasing, γ' ordered phase is firstly precipitated, followed by θ ordered phase. There is a competition relationship between θ and γ' ordered phases during growth and coarsening process. No matter which first precipitates, θ ordered phase always occupies advantage in the competition process of coarsening, thus, the microstructure with preferred orientation is formed.