Simultaneously Enhanced Mechanical Properties and Damping Capacities of ZK60 Mg Alloys Processed by Multi-Directional Forging

Abstract

In this study, the mechanical properties and damping capacities of cast Mg-5.5Zn-0.6Zr (weight percent, ZK60) alloys have been simultaneously improved by a facile multi-directional forging (MDF) processing, and the mechanisms of microstructure evolution and texture modification are systematically investigated. The activation of tension twinning occurs during the initial MDF stage, due to the coarse-grained structure of the as-cast alloy. With increasing MDF passes, the continuous dynamic recrystallization (CDRX) results in a fine equiaxed-grain structure. The typical non-basal texture is formed in the as-MDFed alloy for 6 passes, with the (0001) planes inclined 60°–70° to forged direction and 10°–20° to transverse direction, respectively. A good balance between the strength (~ 194.9 MPa) and ductility (~ 24.9%) has been achieved, which can be ascribed to the grain refinement, non-basal texture and fine precipitate particles. The damping capacity is remarkably improved after MDF processing, because the severe deformation increases the dislocation density, which effectively enlarges the sweep areas of mobile dislocations.