The characteristics of two-phase Al-Cu and Zn-Al alloys processed by high-pressure torsion

Experiments were conducted on two different two-phase alloys, the Al-33% Cu eutectic and the Zn-22% Al eutectoid. These alloys were processed by high-pressure torsion (HPT) and then measurements were taken to determine the distributions of hardness values across the disk diameters and tensile tests were conducted to examine the potential for achieving superplastic elongations. Both alloys showed grain refinement through the HPT processing but the Al-Cu alloy exhibited a conventional work-hardening with torsional straining whereas the Zn-Al alloy exhibited a work-softening due to the loss of Zn-rich precipitates under the high imposed pressure. Excellent superplastic elongations were achieved in both alloys when pulled in tension at elevated temperatures with a maximum elongation of 1800% in the Zn-Al alloy