Effect of severe plastic deformation on tensile properties and impact toughness of two-phase Zn-40Al alloy

Tensile properties and impact toughness of the severe plastically deformed Zn-40Al alloy were investigated. The material billets were subjected to equal-channel angular extrusion (ECAE). After processing, elongation to failure increased significantly with the increasing number of ECAE passes. ECAE also increased the strength levels after one pass, however, they were reduced with the higher number of passes. The observed softening of the alloy upon multiple ECAE passes was shown to be due to the deformation-induced homogenization and the continuous change in the composition of the constituting phases with the number of passes. In addition, the volume fraction of the hard phase decreased due to dissolution and/or breakage. The impact toughness of the alloy was improved by multi-pass ECAE due to the significant increase in ductility. These findings demonstrate that multi-pass ECAE effectively transforms brittle Zn-Al cast alloys into tougher materials with ductile fracture behavior. (c) 2008 Elsevier B.V. All rights reserved.