Abstract:

The process of γ′ phase precipitating from Ni₇₅Al₁₄Mo₁₁ is studied by a computational simulation technique based on microscopic phase-field kinetics model. We studied the phase transformation with the purpose of clarifying the influence of the nearest interatomic potential V_Ni-Al (the nearest interatomic potential) on the precipitation process of γ′ phase. The result demonstrates that there are two kinds of ordered phases, respective L1₀ and L1₂ in the early stage, and L1₀ phase transforms into L1₂ phase subsequently. For L1₂ phase, Ni atoms mainly occupy α site (face center positions), while Al and Mo atoms occupy β sites (the vertex positions). When V_Ni-Al is increased by 10 MeV, the occupation probability of Ni atoms on α sites and Al atoms on β sites are enhanced. Enhanced V_Ni-Al facilitates clustering and ordering of Al atom, which promotes the formation of the γ′ phase. At last, the simulation result was discussed by employing the thermodynamic stability.

Key words: Interatomic potential, Phase transformation, Microscopic phase-field, Occupation probability