Atomistic modeling of the reordering process of γ′ disordered particles in Ni-Al alloys

Ni-based alloys are used in nuclear applications, including as a window material at isotope production facilities, withstanding high fluxes of different energetic particles like protons. Irradiation disorders the γ′ precipitates that in large extent confer the mechanical properties characterizing these materials. Upon disordering, the γ′ phase transforms into oversaturated γ, degrading the materials properties. Experimentally it is observed that disordering might take place at fairly low irradiation doses. Once the particles are disordered, a competition between dissolution, due to strong concentration gradients in an oversaturated solid solution, and reordering appears. Here, we examine this competition in a model Ni-Al alloy under thermal conditions for different precipitates sizes and temperatures. We observe Al interdiffusion from the supersaturated particle to the matrix. Also, stochasticity appears as an important factor in to where precipitates locate. Stress relaxation seems to modify the precipitation process, with a stronger interface effect compared to rigid lattice simulations.