Microscopic phase-field simulation including elastic strain energy for early precipitation process of Ni-Al alloys with medium Al content

The early precipitation process of Ni-Al alloy was studied on the atomic scale based on the microscopic phase-field kinetic model. We investigated the effect of elastic strain energy on precipitation mechanism and morphological evolution of the alloy. Simulation results show that at the early stage of precipitation, γ' ordered phase presents non-directional and irregular shape during the process of aging, the γ' ordered phases change into the quadrate shape and their orientations become more obvious; at the later stage, the γ' precipitates present quadrate shape with round corner and align along the [100] and [010] directions. The mechanism of early precipitation for Ni-13at.%Al alloy is the mixed mechanism of non-classical nucleation growth and spinodal decomposition and near to non-classical nucleation growth, and the mechanism of early precipitation for Ni-15.8at.%Al alloy is the mixed mechanism of non-classical nucleation growth and spinodal decomposition and near to spinodal decomposition.