挤压变形对Mg-2.5Nd-0.5Zn-0.5Zr合金微观组织和力学性能的影响

The microstructure and mechanical properties of Mg-2.5Nd-0.5Zn-0.5Zr alloy prepared with different extrusion ratios were studied by means of scanning electron microscopy, transmission electron microscopy, X-ray diffraction and tensile test. The results show that the initial material is approximately equiaxed grain with average grain size of 23.8 μm. A large number of divorced eutectic Mg₁₂Nd phases are precipitated along the grain boundary, and the eutectic phases present a continuous network distribution at the grain boundary. After extrusion, the microstructure is obviously refined, and the average grain sizes of E1 (extrusion ratio of 7.65) and E2 (extrusion ratio of 12.56) alloy are 8.1 and 6.3 μm, respectively.The mechanical properties are improved remarkably, and the tensile strength, yield strength and elongation of E1 alloy are 231 MPa, 152 MPa and 18.9%, respectively. The tensile strength, yield strength and elongation of E2 alloy are 257 MPa, 213 MPa and 22.4%, respectively. The anisotropy index of E2 alloy sheet is significantly lower than that of E1 alloy. The results show that the anisotropy of Mg-2.5Nd-0.5Zn-0.5Zr alloy sheet can be effectively alleviated by increasing extrusion ratio.