An experimental study on the alignment of cavities in a superplastic commercial copper alloy

A detailed study of cavitation was conducted in a commercial copper alloy deformed superplastically at a strain rate of 1.3 × 10^-3 s^-1. Cavities are observed to form in stringers parallel to the tensile axis due to cavity nucleation around aligned stringers of large cobalt-rich particles present in the as-received alloy. The increase in the number density of cavities and the range of cavity sizes observed indicates that cavities nucleate continuously during superplastic deformation. At large elongations, the interlinkage of cavities in a direction perpendicular to the tensile axis tends to mask the alignment of cavity stringers. It is demonstrated that the present results can rationalize satisfactorily the previous observations of cavity alignment in the superplastic copper alloy. Formerly with the Department of Materials Science, University of Southern California, Los Angeles, CA