Interfacial instabilities and structure during high velocity sliding

Interfacial sliding under high pressure loading at high velocities (0 $<$ v $<$ 1 km/s) results in a variety of mesosc ale phenomena at extreme strain rates. For ductile metal interfacial pairs, these include nano- and mesoscale dynami c strucutral transitions, local melting and amorphization, material mixing, and localization of plastic deformation. We illustrate these phenomena with large scale NonEquilibrium Molecular Dynamics (NEMD) simulations for Cu/Ag, Ta/Al, and Al/Al interfaces. These suggest universal behavior in sliding velocity for the frictional force and a scaling form for the frictional force vs. velocity at high velocities which will be discussed.