Shock-induced deformation faults in 70/30 copper-zinc alloy

Abstract

The microstructure and mechanical strength of shock-deformed 70/30 copper-zinc alloy have been investigated by electron microscopy and hardness testing. Essentially three types of defect structures were produced in the alloy when subjected to shock compressive waves in a pressure range of 50-400 kb. These included dislocations, stacking faults and twin-type structures. The dislocation structures consist of bundles of parallel dislocations plus a limited number of stacking faults which have been activated on {111} planes. The absence of a dislocation cell structure appears to be a consequence of the low stacking fault energy of 70/30 copper-zinc alloy. At high pressures imperfect fault bands occur in the matrix which have a predominant twin orientation. The observed increase in residual hardness is attributable to the shock-induced dislocation and twin-fault densities. The magnitudes of such increases in strength were found to be consistent with recent theory of flow stress and work hardening.