KINETICS OF RADIATION-INDUCED DISORDERING OF A3B INTERMETALLIC COMPOUNDS - A MOLECULAR-DYNAMICS-SIMULATION STUDY

Intermetallic compounds are susceptible to disordering when exposed to irradiation with energetic particles. However, the atomistic mechanisms of this process are not fully understood. We present molecular-dynamics studies of the kinetics of disordering induced by 5-keV energetic displacement cascades in Cu3Au and Ni3Al. Our results show that the underlying crystalline structure is lost in the local region of the cascade core. However, kinetic constraints imposed by the fast quenching rate of the cascade region prevent a complete loss of chemical short-range order from occurring. After the cascade energy dissipates, the Bragg-Williams long-range-order parameter in the central region is found to have a value near zero. The shape of the interface between the cascade-induced disordered region and the surrounding ordered lattice is shown to depend on the ordering energy of the irradiated compound.