Effect of equal-channel angular extrusion on the mechanical and tribological properties of as-cast Zn–40Al–2Cu–2Si alloy

Abstract

As-cast Zn–40Al–2Cu–2Si alloy was processed using equal-channel angular extrusion/pressing (ECAE/P) at 230 °C for four passes following route-B C. After processing, the room temperature mechanical properties (strength, ductility and impact toughness) and dry sliding wear and friction characteristics of the alloy were investigated. After four-pass ECAE, the tensile elongation to fracture of the alloy increased from 0.8% to 14.4% without a considerable decrease in its strength values. The impact toughness also increased and the as-cast brittle alloy was transformed into a ductile and tougher alloy after processing. Such enhancements are attributed to the breakage of large dendrites and fragmentation of copper-rich-phase and Si particles into finer structures, and deformation-induced homogenization of the microstructure during multi-pass ECAE. Wear resistance of ECAE-processed Zn–40Al–2Cu–2Si alloy was notably improved especially at longer sliding distances and under higher applied pressures compared to the as-cast alloy. It was also found that the ECAE processing decreased the friction coefficient of the alloy.