Sn对铸态Mg-5Gd-3Y-0.5Zr合金组织和力学性能的影响

Effect of Sn on Microstructure and Mechanical Properties of As-cast Mg-5Gd-3Y-0.5Zr Alloy

采用X射线衍射仪、光学显微镜、扫描电镜、能谱仪和电子拉伸试验机,研究了不同Sn含量对Mg-5Gd-3Y-0.5Zr合金显微组织、力学性能以及拉伸断口形貌的影响。结果表明,铸态Mg-5Gd-3Y-0.5Zr合金主要由基体α-Mg、Mg_(5)Gd和Mg_(24)Y_(5)相组成,Sn的添加能够细化合金组织,在合金中生成新相Sn_(3)Y_(5),促进合金中第二相的析出。Mg-5Gd-3Y-0.5Zr-0.5Sn合金中第二相呈现出分布均匀的颗粒状,Mg-5Gd-3Y-0.5Zr-1.0Sn合金中部分区域出现了长条状第二相,Mg-5Gd-3Y-0.5Zr-1.5Sn合金中部分区域出现了方块状第二相。在本文研究范围内,随着Sn含量的增加,合金的抗拉强度、伸长率以及布氏硬度都呈现出先上升后下降的趋势。Sn含量为0.5%时,铸态合金综合性能最好,此时合金的抗拉强度、伸长率以及布氏硬度分别为177 MPa、6.87%和57.47 HBW,与无Sn合金相比分别提高了5.36%、12.25%和11.96%。

The effects of Sn content on the microstructure,mechanical properties and tensile fracture morphology of Mg-5Gd-3Y-0.5Zr alloy were studied by X-ray diffraction,optical microscopy,scanning electron microscopy,energy dispersive spectrometer and electronic tensile testing machine.The results show that the as-cast Mg-5Gd-3Y-0.5Zr alloy is mainly composed ofα-Mg matrix,Mg_(5)Gd and Mg_(24)Y_(5).The addition of Sn can refine the microstructure,generate new phase Sn_(3)Y_(5),promote the precipitation of the second phase in the alloy.The second phase in Mg-5Gd-3Y-0.5Zr-0.5Sn alloy shows uniform granular distribution.Elongated second phase appears in the middle region of Mg-5Gd-3Y-0.5Zr-1.0Sn alloy and block-like second phase appears in the middle region of Mg-5Gd-3Y-0.5Zr-1.5Sn alloy.Within the scope of this study,with the increase of Sn content,the tensile strength,elongation and Brinell hardness show a trend of first increasing and then decreasing.When Sn content is 0.5%(mass fraction),the comprehensive properties of as-cast alloys are the best,and the tensile strength,elongation and Brinell hardness of the alloy are 177 MPa,6.87%and 57.47 HBW,with increases of 5.36%,12.25% and 11.96%,respectively,compared with the alloy without Sn alloy.