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采用真空扩散焊在不同焊接温度下对AZ31B镁合金和6061铝合金进行连接。利用光学显微镜(OM)、扫描电镜(SEM)和能谱(EDX)观察Mg/Al异种金属接头的显微组织。结果表明:随着焊接温度的升高,扩散区各层的厚度增加,且组织发生明显变化。440°C时扩散层由Mg2Al3层和Mg17Al12层组成;460和480°C时由Mg2Al3层、Mg17Al12层和Mg17Al12与镁基固溶体的共晶层组成。随着加热温度的升高,高硬度区域显著增多,区域内不同位置的硬度存在明显差别。当焊接温度为440°C时接头的最大抗拉强度为37MPa,脆性断裂发生在Mg17Al12层。
Vacuum diffusion welding is used to connect AZ31B magnesium alloy and 6061 aluminum alloy at different welding temperatures. The microstructure of Mg / Al dissimilar metal joints was observed by optical microscope (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX). The results show that with the increase of the soldering temperature, the thickness of each layer in the diffusion zone increases and the microstructure changes obviously. The diffusion layer consists of Mg2Al3 layer and Mg17Al12 layer at 440 ° C, and consists of eutectic layer of Mg2Al3 layer, Mg17Al12 layer and Mg17Al12 and Mg-based solid solution at 460 and 480 ° C. With the increase of heating temperature, the areas with high hardness increased significantly, and the hardness at different positions in the area differed significantly. When the welding temperature is 440 ° C, the maximum tensile strength of the joint is 37 MPa, and the brittle fracture occurs on the Mg17Al12 layer.