Molecular dynamics simulation of WC/WC grain boundary sliding resistance in WC-Co cemented carbides at high temperature

Grain boundary sliding is thought to be an important deformation mechanism in WC-Co based cemented carbides at high temperature. It has been assumed that when the WC skeleton breaks up and grain boundaries are infiltrated by Co, sliding is facilitated. In this work, molecular dynamics simulations with classical interatomic potentials were used to perform simulations of grain boundary sliding at two model WC/WC grain boundaries. Shear stresses were calculated for different numbers of Co layers in the grain boundary at the constant sliding velocity 10 m/s for T = 500 K, 1000 K, 1500 K, and 2000 K. It was found that in all considered cases, about 6 layers of Co in the grain boundary were sufficient to significantly facilitate sliding. The shear stresses that were obtained are an order of magnitude lower with a Co film (≥ 6 layers) compared to the most stable configurations containing half a monolayer of Co for T ≤ 1500 K, and two orders of magnitude lower for a 12 monolayer thick film at T = 2000 K, which is above the melting temperature of Co (1768 K).