Kinetics of order-disorder transformations in the heusler AuAgZn2 alloy

The kinetics of order-disorder transformations in the Heusler AuAgZn2 alloy was analyzed theoretically by taking into account the interchanges of atoms with neighboring vacancies. The variation of the degrees of the B2- and the L21-type orders, S1 and SH respectively, was calculated during isothermal annealing and during heating or cooling processes. During isothermal annealing, S1, and SHshowed the relaxation phenomena. During heating and cooling processes, Sl, SH−T curves showed hysteresis. Moreover, during heating, the S1−T curve had a minimum at the critical temperature of the L21-type structure Tc2, which was dependent on the heating rate of specimen. The interchanges of atoms with vacancies between the 1st nearest neighbors as well as those between the 2nd nearest neighbors were found to play an important role on the kinetic behavior of ordering in the Heusler alloy.