Mg-Nd-Gd-Zn-Zr-xY合金的组织及力学性能

Microstructure and Mechanical Properties of Mg-Nd-Gd-Zn-Zr-xY Alloy

采用气体保护熔炼Mg-Nd-Gd-Zn-Zr-xY镁合金(x=0,1.4,2.2,3.4,质量分数,%)。通过光学显微镜(OM)、扫描电镜(SEM)、能谱分析(EDS)等手段研究了Y元素对合金的铸态组织、元素分布及热处理后力学性能的影响,并对其拉伸断口进行分析。结果发现,向Mg-2.7Nd-1.5Gd-0.4Zn-0.5Zr合金中加入3.38%的Y后,合金的平均晶粒尺寸由56μm减小至48μm,表明Y元素对合金组织有一定的细化效果。此外,Y含量增加,合金晶界附近元素富集区域面积增大,合金热处理后的抗拉强度、屈服强度及硬度随Y含量增加而上升,伸长率在Y含量为1.4%时达到最高,然后随着Y含量进一步升高而降低。当Y含量为2.2%时,合金综合力学性能较高,其抗拉强度为327MPa,屈服强度为184MPa,伸长率为5.5%。

Mg-Nd-Gd-Zn-Zr-xY(x=0,1.4,2.2,3.4,%,mass fraction)alloy was melted and prepared by gas protection.The effects of yttrium addition on the as-cast microstructure,element distribution and mechanical properties of the alloy after heat treatment were analyzed by optical microscopy(OM),scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS).The results reveal that average grain size of Mg-2.7Nd-1.5Gd-0.4Zn-0.5Zr alloy is decreased from 56μm to 48μm with 3.38%yttrium addition,which indicates that yttrium can refine the microstructure of the alloy to some extent.The tensile strength,yield strength and hardness of the alloy can be improved along with the increase of yttrium after heat treatment as a result of the increase of enrichment element area at grain boundary.When yttrium addition reaches 1.4%,the elongation of the alloy reaches the maximum value.With the Y addition of 2.2%,the comprehensive mechanical properties of the alloy present desirable,where the tensile strength,yield strength and elongation of the alloy reach 327 MPa,184 MPa and 5.5%,respectively.