The temporal evolution feature of a microscopic phase field model was used to study the antisite defects of L12-Ni3Al. There were two main observations. Firstly antisite defects NiAl and AlNi, which were caused by deviation from stoichiometric Ni3Al, coexisted in the Ni3Al phase. The surplus Ni atom in the Ni-rich side was prone to replace Al; thus producing the antisite defect NiAl that maintained the stability of the L12 structure. In another case, the surplus Al atom in the Al-rich side was accommodated by a Ni sub-lattice, thus giving rise to the antisite defect, AlNi. The calculated equilibrium occupancy probability of NiAl was much higher than that of AlNi. This point was generally in line with other theoretical and experimental work. Additionally, both NiAl and AlNi had a strong negative correlation to the time step during the disorder-order transformation. Since the initial value of NiAl and AlNi on each site of the matrix was right at the given concentration, it was possible to observe the decrease in NiAl and AlNi from the initial disordered high anti-structure state to their respective equilibrium states.

Microscopic Phase Field Study of the Antisite Defect of Ni3Al in Binary Ni-Al Alloys. Zhang, J., Chen, Z., Lu, Y., Zhang, M., Wang, Y.: Science China: Physics, Mechanics and Astronomy, 2010, 53[11], 2047-53