Effect of Y content and equal channel angular pressing on the microstructure, texture and mechanical property of extruded Mg-Y alloys

Abstract

The microstructure, texture and mechanical property evolution of the extruded Mg- x Y ( x = 1, 5 wt.%) alloys during equal channel angular pressing (ECAP) were systematically investigated using an optical microscope, electron backscatter diffraction (EBSD) and uniaxial tensile test. The Mg-Y alloys exhibited a weakened basal texture before the ECAP, and the texture was further weakened with the max basal poles dispersed along ∼45° between the extrusion direction and the transverse direction after the ECAP. The Mg-5Y alloys always exhibited a finer grain size comparing to that of Mg-1Y for the same ECAP process. With a proper ECAP process, both the strength and elongation of Mg-5Y alloy could be improved simultaneously after the ECAP, i.e., the yield strength (273.9 ± 1.2 MPa), ultimate strength (306.4 ± 3.0 MPa), and elongation (23.9 ± 1.0%) were increased by 10%, 6%, and 72%, respectively, comparing to that before the ECAP. This was considered to be arose from the combined effects of grain refinement, significant improved microstructure homogeneity and solid solution hardening. In addition, it was found that Mg-Y alloy with better comprehensive properties could be obtained by the decreasing-temperature ECAP processes. The yield strength-grain size relationship could be well described by the Hall-Petch relation for all the ECAPed Mg-Y alloys, which was consistent with that the texture changes did not significantly affect the average Schmid factors of basal, prismatic and pyramidal slips for both Mg-Y alloys.