Structure and stability of the interface between a strained crystal and a shearing liquid

The results are presented from nonequilibrium molecular dynamics simulations of the stationary nonequilibrium interface between a shearing liquid and its strained crystal. The penetration of the velocity field into the crystal is shown to increase with an increasing shear stress along the coexistence line. Slip and creep compensate within the interfacial region to produce an effective flow boundary well described, macroscopically, by a standard stick boundary condition. The shear flow within the interface is found to involve intermittent stick-slip motion, with the slip accompanied by disordering. A theoretical treatment of the interfacial stability is proposed, based on the competing rates of crystallization and erosion, and is found to provide a reasonable representation of the simulated stress-temperature phase diagram.