Extensive resistometric investigations indicated that the so-called order-order relaxations in this material comprised 2 simultaneous single-exponential processes which strongly differed in rate. In order to explain the experimental results, Monte Carlo simulations of processes in an L12-ordered A3B system were used; on the basis of the Glauber algorithm for the vacancy mechanism for atomic jumps. The configuration energy of the system was approximated by using an Ising formula which involved pair-interactions of atoms in 2 coordination shells. Laplace transformation of the simulated order-order relaxation curves revealed the predominance of 2 relaxation times; one of which was 10 times greater than the other. The contribution which arose from the fast relaxation process was always higher in the case of ordering than in the case of disordering. It was noted that the fast relaxation process consisted of the creation (disordering) or recombination (ordering) of the nearest-neighbour A- and B- antisite pairs. The slow relaxation process was a highly complex cooperative one, which finally led to the equilibrium degree of long-range order with a new distribution of the antisite atoms.

Monte Carlo Simulation of Atomic Migration in L12 Superstructure. Oramus, P., Kozubski, R., Cadeville, M.C., Pierron-Bohnes, V., Pfeiler, W.: Solid State Phenomena, 2000, 72, 209-14