Abstract: The effect of rotational-die equal channel angular pressing (RD-ECAP) temperature and deformation route on the microstructure and mechanical properties of pre-extruded Mg-5Gd-3Y-1Zn-0.5Zr (wt%) alloys were investigated. The results indicate that the RD-ECAP updates both the α-Mg texture and long-period stack-ing ordered (LPSO) arrangement in the pre-extruded alloy, while the α-Mg texture is more sensitive to the change of deformation route. The LPSO streamlines modify the anisotropy of mechanical properties of the ECAP alloys via exerting different reinforcing effects and modifying the crack propagation. The lower ECAP temperature of 350 ℃ rather than 400 ℃ promotes dynamic precipitation which deteriorates the following ageing-hardening response but conduces to refining the α-Mg grains and preventing a sharp drop in elongation after peak ageing. The 350A peak-aged alloy exhibits the optimal mechanical proper-ties with the average tensile yield strength (TYS) of 311 MPa (STYS = 3.7, S indicates standard deviation) and elongation of 7.6 % (SEL = 0.7). Its higher strength should mainly be attributed to the finer grain size, and its quasi-isotropic performance should be inherited from the ECAP state induced by the rational arrangement of LPSO phases.

Key words: Mg alloys, Long-period stacking ordered, Equal channel angular pressing, Microstructure, Mechanical property, Anisotropy