Abstract:A microscopic phase-field model was used to investigate a directional coarsening mechanism caused by the anisotropic growth of long period stacking and different effects of phases on precipitation in Ni-Al-V alloy. The results show that DO₂₂ mainly coarsens along its short axis, which may press the neighboring L1₂, leading to the interaction among atoms. Diffusion channels of Al are formed in the direction where the mismatch between γ′ and γ reduces; the occupation probabilities are anisotropic in space; and direction coarsening of L1₂ occurs finally. With a rise of ageing temperature, phases appear later and DO₂₂ is much later at a higher temperature, the average occupation probabilities of Al and V reduce, and Al changes more than V.

Key words: nickel-based alloys; microscopic phase-field simulation; directional coarsening; anisotropic growth; mismatch; diffusion