Kinetics of "order-order" relaxations in Ni3Al studied by computer simulation

The experimental investigations of "order-order" kinetics in Ni3Al-based L1 (2)-ordered intermetallic compounds revealed the relaxation curves composed of two parallel processes considerably differing in relaxation rates. A si mple Ising-type model based on a vacancy mechanism of atomic jumps was used to carry the Monte Carlo simulations of long-range-order relaxations in a binary A(3)B system with L1(2)-type superstructure. The simulated relaxatio n curves fitted weighted sums of two exponentials with significantly differ ent relaxation times. It was found out that the fast relaxation process is controlled by the dynamics of the minority B-atom jumps.