Ion-beam mixing in energetic collision cascades: Thermal-spike model and experiments

A phenomenological model of ion-beam mixing during energetic collision casc ades is developed, based on the concept of a thermal spike, to correctly pr edict that the mixing rate Dr depends linearly on nuclear stopping power (i nstead of a power-law dependence), and is correlated with a heat of mixing (analogous to Darken's relation). Previous ion-beam mixing experiments from 25 different metallic bilayers agree well with the model's predictions: mi xing rates (Dt)/(ion-dose) similar to 1 nm(4), and an activation enthalpy o f approximately 1 eV for atomic diffusion in liquid-like cascades.