The Effects of Nanostructure upon the Dynamic Ductile Fracture of High Purity Copper

Dynamic fracture is a fundamentally important physical process. However, the effect of material nanostructure, including both lattice and grain structure, and their respective defects, on such events is not well understood. Ductile fracture is widely accepted to proceed through the nucleation, growth and coalescence of voids to form a failure plane. The formation of voids at grain boundaries is established, and impurities and secondary phase particles are often found at the centre of these voids suggesting their involvement in the nucleation process. In a pure metal, where impurities are absent, the void nucleation process is unclear, although theories suggest the importance of dislocations and their substructures. Dislocation parameters are underpinned by the plasticity behaviour of the relevant material, which is often highly strain rate dependent, and in the case of copper, is also history dependent.