The Ni <sub> 75 </ Sub> Al <sub> The X </ Sub> V <sub> 25-x </ Sub> Alloy Precipitation Behavior Of Microscopic Phase Field Simulation

The regulation of incubation time, precipitation sequence and mechanism of Ni-Al-V alloy on the effect of temperature and concentration was first studied using the microscopic phase-field method, and the interphase boundary structure of ordered domain migration characteristic of interphase boundary and nucleation orientation was investigated.As the temperature lower, the incubation time of the y' phase and θ phase is shorten and the nucleation ratio increase and the growth velocity quicken. The incubation time prolong with the minish of Al concentration, and the transition of two phases from θ phase forms firstly to θ phase and y' phase form simultaneously and then to y' phase forms firstly.The correlation between precipitation mechanism and temperature and concentration was demonstrated. As the temperature lower, the precipitation mechanism of θ phase of Ni₇5Al₄.5V₂0.5 alloy transform from non-classical nucleation to congruent ordering + spinodal decomposition, and the γ' phase transform from non-classical nucleation to the mixed style of non-classical nucleation+ spinodal decomposition. The precipitation mechanism of θ phase of Ni₇5Al₆.5V₁8.5 alloy transform from non-classical nucleation+ spinodal decomposition to non-classical nucleation, and the y' phase transform from non-classical nucleation+ spinodal decomposition to congruent ordering + spinodal decomposition. The precipitation mechanism of 0 phase of Ni₇5Al₇.5V₁7.5 alloy is non-classical nucleation, and the γ' phase transform from non-classical nucleation+ spinodal decomposition to congruent ordering + spinodal decomposition.There are exist three, eight and four kinds of interphase boundaries respectively between the γ' (L1₂) phases, θ (D0₂2)phases and γ' (L1₂) phases and 0 (D022)phases. According to the matching relation and the structure of the interphase boundary, the interphase can be divide into removable and immovability, which have great effect to the evolution and precipitation of the interphase boundary. The ordered interphase dissolve into disordered area when the (004) θ and (001)θ plane encounter at the [010] θ directions, but the γ' phase precipitate at the interphase boundary when (001)θ and (001)θ plane encounter. The nucleation position and growth direction of γ'(L1₂) and θ(D0₂2) have the selective orientation at the ordered interphase boundaries.