Solid-fluid transitions at high sliding rates at Al/Al interfaces

Large scale NonEquilibrium Molecular Dynamics (NEMD) simulations (1.4 $10^{6}$ atoms) for single crystal Al have shown a transition as a function of sliding velocity from a defective solid phase to a fluid phase beyond a critical velocity, $v_{c}$, which depends very nearly linearly with the homologous temperature $T/T_{m}$ where $T_{m}$ is the melting temperature and $T$ is the sample temperature far from the interface. Above $v_{c}$, a Couette flow pattern develops with a slope which is independent of velocity. We discuss the properties of this transition and the power law dependence of the frictional force with velocity observed in this regime.