Laser shock experiments, carried out using an energy density of 61MJ/m2, revealed void initiation and growth after stress application times of about 10ns. It was shown that void growth could not be achieved by vacancy diffusion under these conditions; even in the presence of shock heating. An alternative dislocation-emission based mechanism was proposed for the void growth. The shear stresses were highest at 45° to the void surface, and decayed with increasing distance from the surface. Two mechanisms were proposed which accounted for the generation of the geometrically necessary dislocations (prismatic and shear loops) required for void growth. A criterion was proposed for the emission of a dislocation from the surface of a void under remote tension. This was analogous to the Rice-Thomson criterion for crack blunting by dislocation emission from the crack tip. The critical stress was calculated for the emission of a single dislocation, and a dislocation pair, for any initial void size. It was shown that the critical stress for dislocation emission decreased with increasing void size. Dislocations with a wide core were more easily emitted than were dislocations with a narrow core.

Void Growth by Dislocation Emission. V.A.Lubarda, M.S.Schneider, D.H.Kalantar, B.A.Remington, M.A.Meyers: Acta Materialia, 2004, 52[6], 1397-408