MgAlSn钎料钎焊AZ61镁合金的钎缝显微组织及力学性能

Brazed seam microstructure and mechanical properties of magnesium alloy AZ61 with MgAlSn filler metal

用一种MgAlSn镁合金钎料对变形镁合金AZ61执行了高频感应钎焊,研究了MgAlSn钎料的显微组织、钎焊接头的显微组织及力学性能。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、X射线能谱分析仪(EDS)等分析了钎料的显微组织和钎焊接头的界面显微组织及钎缝物相,测试了钎焊接头的强度。结果表明:在钎焊过程中钎料与镁合金母材发生界面冶金反应,在钎缝中钎料的原始显微组织形貌消失,由于合金化作用在钎缝中形成新的钎缝显微组织并形成新相α-Mg。钎焊对接接头的平均抗拉强度为45 MPa,搭接接头的平均抗剪强度为36 MPa。接头断口的主要断裂形式为沿晶脆性断裂,断裂位置主要产生于硬脆α-Mg+β-Mg_(17)Al_(12)处。

Wrought magnesium alloy AZ61 was joined by high- frequency induction brazing with MgAlSn filler metal.Microstructure of the filler metal,the interface microstructure and formation phases of brazed seam were investigated by X-ray diffraction instrument(XRD),scanning electron microscopy(SEM) and X- ray energy dispersive spectrometer(EDS).The mechanical properties of the brazed joint were tested.The results show that filler metal has interface metallurgy reaction with the base metal magnesium alloy AZ61.The original microstructure of the filler metal disappears after the brazing process.The experimental results show that α-Mg phase forms in the brazing region due to the intensive alloying in the brazing process.The tensile strength and shear strength of the brazed joints is 45 MPa and 36 MPa,respectively.The intergranular fracture initiates the hard and brittle phases of α-Mg +β-Mg_(17)Al_(12).