A metallographic and quantitative analysis of the influence of stacking fault energy on shock-hardening in Cu and Cu-Al alloys

This paper deals with the mechanical behavior of Cu and solid-solution Cu-A l alloys that were shock-deformed to 10 and 35 GPa. All the shock-deformed materials showed shock-strengthening that was greater at higher shock press ure and decreased with decreasing stacking fault energy (SFE) at both shock pressures. In the literature. shock-strengthening has been qualitatively a scribed to a greater dislocation density and the formation of deformation t wins without addressing the question as to why shock-strengthening is lower in low SFE materials. This question is addressed in the present work by qu antifying the twin contribution to the total post-shock strength. The twin contribution was found to increase with decreasing SFE suggesting that the contribution of dislocations concurrently decreases. The stored energy of a s-shock deformed materials was measured and found to decrease with decreasi ng SFE implying a lower net stored dislocation density in the lower SFE all oys. It is suggested that a lower net stored dislocation density in low SFE alloys results in the observed lower shock strengthening. (C) 2001 Acta Ma terialia Inc. Published by Elsevier Science Ltd. All rights reserved.