Atomic anti-site evolution during L12 precipitation using microscopic phase-field simulation

The influence of temperature on atomic site occupation probability (SOP) in L1(2)-Ni-3(Al1-xFex) has been studied using microscopic phase-field simulation for Ni3Al-Fe alloy with the lower Fe content. Microscopic phase-field kinetics model was further extended to study the temporal evolution of atomic site occupation and atomic anti-sites behavior, which was revealed in detail at the different temperatures. The results show that the size, number and the precipitation mechanism of L1(2) phases also present obvious changes with the increase of temperature. The SOP of each atom on its right-sites decreases slowly; while the SOP of Fe atoms are far lower than those of Al atoms. On the other hand, the SOP of each atom on its anti-sites increases gradually. The formation of Ni-Al (Ni atoms form anti-sites on Al sites) is more easily and the formation of Ni-Al is more sensitive to temperature than that of Fe-Ni (Fe atoms form anti-sites on Ni sites). Atomic site occupation will not evolve during the early stage of precipitation, which becomes more and more obvious.