Molecular dynamics studies of a model system were used to determine the role of thermomigration under the extreme conditions which were characteristic of a heat spike following a collision cascade. By studying heat spikes in liquid alloys, it was possible to isolate the Soret effect and determine the magnitude of the heat of transport. It was found that this effect could give rise to an increase or decrease in the solute content at the core of a cascade. In the particular case of the Au-Ni system (with complete solubility in the high-temperature solid phase and above), Ni as solute exhibited a tendency to move toward the hot core of the spike. The opposite was true with Au as the solute. This effect appeared in a system whose initial condition before irradiation was the equilibrium thermodynamic phase which was predicted by the phase diagram. Therefore, no solute motion was expected.

Thermomigration Produced by Collision Cascades in Solid Solutions. E.Lopasso, M.Caro, A.Caro: Physical Review B, 2001, 63[17], 174105 (6pp)