Y对Mg-Nd-Zn-Zr铸造镁合金组织和性能的影响

摘要

Effects of Y on microstructure and mechanical properties of Mg-Nd-Zn-Zr cast alloys were investigated by the optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and mechanical properties test. The results show that the mainly composition of as-cast Mg-Nd-Zn-Zr-xY (x=0, 0.6%, 1.2%, 1.8%, mass fraction) involves a-Mg and Mg12(NdaZn1-a) phase and the Y elements dissolved in them; the microstructure of the solution-treated alloys involves a-Mg, remnant Mg12(NdaZn1-a) phase and cuboid-shaped Mg24RE5 compound; after peak-aged, there areβ' andβ" phases precipitating with average sizes of 10 nm which obviously strengthen the matrix; the yield strength and ultimate tensile strength of the alloys are increased with the increasing content of Y, the maximum values reach 271 Mpa and 161 Mpa, respectively, which are evidently higher than that of the standard Mg-Nd-Zn-Zr alloy.%采用光学显微镜、扫描电镜、透射电镜和X线衍射仪等分析研究Y对Mg-Nd-Zn-Zr铸造镁合金组织和性能的影响,并测试其室温力学性能.研究结果表明:Mg-Nd-Zn-Zr-xY(x=0,0.6％,1.2％,1.8％,质量分数)合金铸态组织主要由α-Mg和Mg12(NdaZn1-a)相组成,Y元素主要固溶在α-Mg和Mg12(NdaZn1-a)相中；合金经530℃/14h固溶处理后组织由α-Mg、残余的少量Mg12(NdaZn1-a)相以及方块状Mg24RE5相组成；固溶态合金经200℃/12h时效处理后有大量尺寸为10nm左右的β'和β”析出相生成,能有效地强化基体；随Y质量分数增加,合金室温抗拉强度和屈服强度逐渐上升,最高分别达到271 MPa和161 MPa,较基础Mg-Nd-Zn-Zr合金有较大幅度提高.