Effect of irradiation on mechanical properties of symmetrical grain boundaries in BCC tungsten: an atomistic study

The effect of displacement cascade on the mechanical properties of symmetrical grain boundaries in BCC tungsten has been studied by molecular dynamics method. At first, results show that the point defects induced by displacement cascade are absorbed by the grain boundary, in which the number of absorbed interstitials is more than that of vacancies. Then, displacement cascade can decrease both the ultimate strength in tensile simulation and the critical stress in shear simulation. The change of microstructure and mechanism during deformation has been investigated. During tensile deformation, vacancy clusters promote the formation of micro-cracks and interstitial clusters accelerate the nucleation of 1/2 < 111 > dislocation loops. In terms of shear loading, the migration of grain boundary could be significantly enhanced by displacement cascade.