Low-temperature superplasticity in a Cu-Zn-Sn alloy processed by severe plastic deformation

A copper alloy containing similar to 38% Zn and similar to 3% Sn was subjected to severe plastic deformation at a temperature of 400 degreesC using the procedure of equal-channel angular pressing (ECAP). The microstructures produced by ECAP were relatively heterogeneous with areas of both recrystallized and unrecrystallized grains. Within the recrystallized areas, the average grain size was similar to 1.5 mum. Tensile testing after ECAP revealed the occurrence of superplasticity with elongations up to similar to 900%. Superplastic ductilities were recorded at temperatures as low as 300 degreesC corresponding to an homologous temperature of similar to 0.51T(m), where T(m) is the absolute melting temperature of the alloy. These results demonstrate the potential for achieving low temperature superplasticity in this alloy through ECAP. As in conventional superplastic Cu-based alloys, specimens failed because of the development of internal cavities. (C) 2001 Elsevier Science B.V. All rights reserved.