Temperature dependence of the pre-wetting transition at the (111) anti-phase boundary in Ni3Al: an atomistic study

Chemical composition and ordering at the (1 1 1) anti-phase boundary (APB) in the Ni3Al-based gamma' phase have been studied by semi-grand canonical Monte Carlo simulations at temperatures from 700 to 1300 K. The atomic interactions are modeled with an embedded-atom potential reproducing the relevant part of the Ni-Al phase diagram. In a certain range of bulk compositions and temperatures within the gamma' phase stability domain, the APB undergoes a pre-wetting transformation by becoming a layer of disordered gamma phase. The pre-wetting transformation line is mapped onto the bulk phase diagram allowing predictions of the APB state under various thermochemical conditions.