It was recalled that one of the low-temperature failure mechanisms in ductile metallic alloys was the growth of voids and their coalescence. An attempt was made here to obtain atomistic insights into the mechanisms which underpinned cavitation in the representative metal, aluminium. Often the pre-existing voids in metallic alloys such as Al had complex shapes (e.g. corrosion pits) and the deformation/damage mechanisms exhibited a rich size-dependent behaviour at various material length-scales. Attention was focussed here on these two issues via large-scale calculations for specimens with sizes ranging from 18000 to 1080000 atoms. In addition to the elucidation of the dislocation propagation based void growth mechanism, the observed length scale effect reflected in the effective stress–strain response, stress triaxiality and void fraction evolution was highlighted. As expected, the conventionally used Gurson model failed to capture the observed size-effects; thus calling for a mechanistic modification that incorporated the mechanisms observed in the current and earlier simulations. Finally, in the present multi-void simulations, it was found that the splitting of a big void into a distribution of small ones increased the load-carrying capacity of specimens. However, no obvious dependence of the void fraction evolution upon void coalescence was observed.

Atomistic Insights into Dislocation-Based Mechanisms of Void Growth and Coalescence. C.Mi, D.A.Buttry, P.Sharma, D.A.Kouris: Journal of the Mechanics and Physics of Solids, 2011, 59[9], 1858-71