Molecular dynamics computer simulations of intermetallic compounds were carried out in order to investigate the kinetics of disordering and amorphization. These systems were chosen because reliable embedded-atom potentials were available for the constituents and their alloys, and because extensive experimental results were available. Previous simulations of collision cascades which resulted from 5keV Cu and Ni primary knock-on atoms had revealed a marked difference between the evolution of the short-range order and crystalline order parameters in all of the intermetallics. That is, complete loss of crystalline structure and only partial chemical disorder in the core of the cascade. The present work dealt with the simulation of the amorphization of NiAl by 5 and 15keV primary knock-on Ni atoms. The kinetic energy of atoms in the simulated material was removed at various time-scales so as to mimic strong or weak coupling between electrons and phonons. No evidence of amorphization was found at the end of the cascades that were created by 5keV recoils. However, 15keV primary knock-on studies showed that, in the no-coupling case, the system evolved into a highly disordered state. An amorphous region with about 100 non-lattice atoms was found in the case of weak coupling. Locally melted and recrystallized regions collapsed into small dislocation loops when medium coupling was assumed, and a highly ordered state resulted in the case of strong coupling.

M.Spaczer, A.Caro, M.Victoria, T.Diaz de la Rubia: Nuclear Instruments and Methods in Physics Research B, 1995, 102[1-4], 81-5