Investigation of microstructure and mechanical properties of ZK60 magnesium alloy achieved by extrusion-shearing process

Abstract

The microstructure characterization, mechanical properties and texture evolution of a ZK60 alloy achieved via the extrusion-shearing (ES) process were systematically studied with the help of optical microscopy (OM), X-ray diffractometry (XRD), scanning electron microscope (SEM) and electron back-scattered diffraction (EBSD). The results showed that the grain size was refined to ∼1.7 μm and the microstructure became more uniform. The tensile yield strength and ultimate tensile strength at room temperature of the ES-processed alloy reached 263 MPa and 321 MPa, respectively, which were 35.6% and 10.7% higher than that of the as-annealed alloy. Grain refinement, precipitate strengthening, and dislocation strengthening are the main factors for the improvement in strength. After the ES process, the elongation of ZK60 alloy increased from 16.6% to 23.7%, which is attributed to the activation of the basal slip system and texture modification. Moreover, the tension-compression yield asymmetry of the ZK60 alloy was significantly improved after extrusion, thus indicating that the extrusion-shearing process suggested in this work has great potential for the large-scale application of magnesium alloys.

Keywords

• ZK60 alloy
• Extrusion-shearing
• Microstructure
• Mechanical properties
• Tension-compression yield asymmetry