Microstructure evolution and mechanical properties of Mg-Gd-Nd-Zn-Zr alloy processed by equal channel angular pressing

A cast Mg-2.9Gd-1.5Nd-0.3Zn-0.3Zr alloy was processed by equal channel angular pressing at 375 °C for 1, 4 and 8 passes. Microstructure, texture and mechanical properties were investigated. The results indicate that the average grain size decreases from ∼50 μm at as-cast state to 1.23 μm during 8-pass ECAP. Homogeneity of microstructure improved obviously and new spherical β1 phase gradually precipitated from α-matrix with the increase of pass. Moreover, the random texture was converted to the strong (0002) basal texture. The ultimate tensile strength (UTS), yield strength (YS) and elongation increased in all passes, and the magnesium alloy obtained the excellent mechanical property at ECAP for 8 pass, for which the UTS, YS and elongation reached to 274.1 MPa, 231.6 MPa and 20.3%, respectively. The increase in strength and ductility was owing to cooperative effects of grain refinement, precipitation strengthening and texture evolution.