Influence of surface energy and thermal effects on cavitation instabilities in metallic glasses

Abstract

To reveal the void dominated fracture mechanism, cavitation instabilities in metallic glasses are studied through analytical and numerical approaches, with particular attention on surface energy and thermal effects. The critical pressure for unbounded growth of voids is determined, which increases apparently as surface energy is taken into account. A dimensionless number Iγ which is a ratio of the energy required to form new void surface and the energy dissipated by plastic deformation is proposed. It is found that the surface energy significantly impedes void growth at the early stage of void growth when Iγ is large. Besides, to address the thermal effects, another dimensionless number Ith, which reflects the competition of momentum diffusion and thermal diffusion, is presented. Results of numerical simulations show that the thermal effects first promote and finally impede the void growth at the late stage of void growth when Ith ≤ 1. Further study on combined influence of inertia, surface energy and thermal effects reveals the factors which are dominant as the process develops.