The effect of hydrostatic pressure on the shear deformation of Cu symmetric tilt interfaces

The effect of hydrostatic pressure on the shear deformation behavior of 10 Cu symmetric tilt interfaces has been investigated in the athermal deformation regime (10 K) using molecular dynamics simulations. Cu bicrystals were deformed under shear with a superimposed hydrostatic stress, until initial yield. For most interfaces, the shear strength increased with increasing compressive hydrostatic pressure. However, for the Sigma 9{221} and Sigma 5{210} interfaces, this trend was reversed. Neither the sign nor the magnitude of the pressure-induced elevation in shear strength was found to correlate with interface structure or particular deformation mechanism(s). The findings suggest that in general, metrics of interfacial excess volume and dilatation cannot reliably predict the pressure-sensitivity of shear strength; however, for interfaces containing the E structural unit, the annihilation of free volume appears to correlate well with the observed pressure-sensitivity.