Microstructure Evolution and Mechanical Properties of Mg-1.5Zn-0.2Ca-0.2Ce Alloy Processed by Accumulated Extrusion Bonding

The microstructure and mechanical properties of Mg-1.5Zn-0.2Ca-0.2Ce alloy sheets processed via accumulated extrusion bonding (AEB) at 523 K were examined in this study. To investigate the microstructure evolution, samples corresponding to various process stages were taken from six locations parallel to the extrusion direction. Many twin boundaries were observed at the initial extrusion stage, and subsequently dynamic recrystallization (DRX) (especially ‘twin-assisted’ DRX and continuous DRX) was activated. With increasing strain, the matrix grains were gradually transformed into new DRXed grains, and the grains were significantly refined to 0.55 μm, whereas the grains grew to 3.1 μm outside the die. After the AEB process, the sheet exhibited almost the same texture as that of the as-received sheet with basal poles tilted to the extrusion direction by ~ ± 30°. The tensile test results revealed that, compared with the as-received sheet, the yield strength of AEBed sheets was improved as much as 50 MPa, resulting mainly from the grain refinement.