Radiation-induced mixing between metals of low solid solubility

We use molecular dynamics to study radiation-induced mixing between low solid solubility metals, focusing on the effect of liquid phase properties, by sequentially performing multiple 10 keV collision cascade simulations up to a total dose of ∼5 displacements per atom (dpa). We find mixing to be proportional to the square root of dose, independent of interface crystallography, and highly sensitive to liquid phase interdiffusivity. It occurs primarily by liquid phase interdiffusion in thermal spikes rather than by ballistic displacements. Partial de-mixing is also seen within thermal spikes, regardless of liquid phase solubility. We attribute it to segregation of impurities into the liquid core of the thermal spikes. We present an expression that relates mixing rates to liquid phase heats of mixing and self-diffusivities.United States. Dept. of Energy. Office of Basic Energy Sciences (Award Number 2008LANL1026