Zn对铸态Mg-Y-Nd-Zr合金组织和力学性能的影响
摘要
Effects of Zn on microstructure and mechanical properties of Mg-Y-Nd-Zr as-cast alloys were investigated by the optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffractometry(XRD) and the mechanical properties test. The results show that the grain size of Mg-Y-Nd-Zr-<i>x</i>Zn(<i>x</i>=0.0%, 0.5%, 1.0%, 1.5%,mass fraction)alloys is greatly refined with the increase of Zn content, which is refined from (57±0.8)μm to (30±0.3)μm. The volume fraction of eutectic structure at grain boundary increases gradually. Mg<sub>12</sub>Nd phase and Mg<sub>24</sub>Y<sub>5</sub> phase exist mainly in Mg-Y-Nd-Zr as-cast alloy. With the addition of 0.5%Zn, Mg<sub>12</sub>YZn phase appears at the grain boundary. With the increase of Zn, the volume fraction of Mg<sub>12</sub>YZn phase and the mechanical properties of the alloys increases gradually. The alloy containing 1.0%Zn exhibits the optimal mechanical properties, the ultimate tensile strength, yield strength and elongation are (208±5.9), (159±3.9)MPa and (7.5±0.2)%, respectively; comparing with the alloy without the addition of Zn, the ultimate tensile strength, yield strength and elongation increase by 18, 42MPa and 1.2%.