Al基钎料钎焊镁合金AZ31B接头的显微组织及力学性能

为了连接变形镁合金AZ31B,以Al基钎料对变形镁合金AZ31B进行高频感应钎焊。采用扫描电镜、X射线衍射仪、X射线能谱等分析钎焊接头的显微组织及钎缝物相,测试钎焊接头的力学性能及显微硬度。结果表明:在钎焊过程中熔融的Al基钎料与固态的AZ31B母材发生强烈的合金化作用,原始钎料中均一的Mg32(Al,Zn)49相在钎焊后完全消失,同时在钎缝中生成α-Mg、β-Mg17(Al,Zn)12相。钎焊搭接接头的平均抗剪强度达到44MPa,对接接头的平均抗拉强度达到71MPa。接头的断裂形式为沿晶脆性断裂,断裂产生在β-Mg17(Al,Zn)12硬脆相处。

Microstructure and Mechanical Properties of AZ31B Magnesium Alloy Brazed Joint Using Al Matrix Filler Metal

In order to join wrought magnesium alloy AZ31B plates,an Al matrix filler metal was developed to join them by means of high-frequency induction brazing. The microstructure and phase constitution of the brazed joint were investigated by scanning electron microscopy,X-ray diffraction and X-ray energy dispersive spectroscopy. The mechanical properties and microhardness of the brazed joint were also tested. The results show that the single Mg32(Al,Zn)49 phase in the original filler metal is consumed after the soldering process;moreover,α-Mg solid solution and β-Mg17(Al,Zn)12 phase are formed in brazing region due to the intensive alloying between the molten filler metal and the base metal in the process of brazing. The average tensile strength of the butted joint is 71 MPa and the average shearing strength of the overlapped joint is 44 MPa. The fracture surface of the brazed joint exhibits an intergranular fracture feature and the crack originates from the hard β-Mg17(Al,Zn)12 phase.