An atomistic study of void growth in single crystalline copper

This paper relates to the simulation of void growth in face centre cubic (fcc) single crystals on the atomic level (10−9 m). An atomistic model is used to capture the large amount of irregularities such as vacancies and void-like vacancy clusters which exist in even the purest real material. The embedded atom method (EAM) is used to describe the atomic interaction and so the material behaviour in a realistic manner. The potential energy of the entire system is minimised to find the equilibrium configuration of any deformed state. Stress–strain curves are plotted for various initial void configurations and crystal orientations under uniaxial tension. The resulting curves show good qualitative agreement with that expected from experiment but predict stress levels close to the theoretical strength of the material. Crack propagation and dislocation glide were seen to occur along the theoretically predicted directions. Comparison is made with crystal plasticity calculations for similar geometries. Again, while the development of the voids in terms of shape and size agree well, the stress levels predicted are an order of magnitude higher than in the crystal plasticity model. Atomistic models contain an inherent failure criterion while such a criterion must be coded into a continuum system without any guarantee of accuracy. In the future, it might be possible to use the failure strain of the atomistic models as a more straightforward guide to determining failure in a continuum model.