Abstract: The atomic scale computer simulation for initial precipitation mechanism of Ni75Al6V19 alloy was carried out for the first time by employing the microscopic diffusion equation. The initial precipitation process was investigated through simulating the atomic pictures and calculating the order parameters of the two kinds of ordered phases. Simulation results show that the ordered phase precipitated earlier than θ ordered phase by congruent ordering+spinodal decomposition mechanism and thus produced a nonstoicheometric single ordered phase. Then, the nonstoichiometricθphase precipitated by a non-classical nucleation and growth mechanism at the APBS of phase.

Key words: Precipitation mechanism, Ni75Al6V19 alloy, (Ni3Al) ordered phase