Effect of Cu on microstructure, mechanical properties, and texture evolution of ZK60 alloy fabricated by hot extrusion-shearing process
(1. School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China;
2. Key Laboratory of Magnesium Alloys and the Processing Technology of Liaoning Province, Shenyang 110870, China)
2. Key Laboratory of Magnesium Alloys and the Processing Technology of Liaoning Province, Shenyang 110870, China)
Abstract: As-cast Mg-6Zn-xCu-0.6Zr (x=0, 0.5, 1.0, wt.%) alloys were fabricated by permanent mold casting; then, the alloys were subjected to homogenization heat treatment and extrusion-shearing (ES) process. The microstructure and mechanical properties of the alloys were evaluated by OM, SEM/EDS, XRD, TEM, EBSD and tensile tests. The results show that the hard MgZnCu phase in Cu-added alloy can strengthen particle-stimulated nucleation (PSN) effect and hinder the migration of dynamic recrystallization (DRX) grain boundary at an elevated temperature during ES. The ZK60+0.5Cu alloy shows an optimal tensile strength–ductility combination (UTS of 396 MPa, YS of 313 MPa, and δ=20.3%) owing to strong grain boundary strengthening and improvement of Schmid factor for {0001} basal slip. The aggregation of microvoids around the MgZnCu phase mainly accounts for the lower tensile elongation of ZK60+1.0Cu alloy compared with ZK60 alloy.
Key words: Mg-Zn-Cu-Zr alloy; extrusion-shearing process; microstructure characterization; mechanical properties; texture evolution; strengthening mechanism