中文摘要：

模板采用冷金属过渡（CMT）焊接工艺，以ER4043铝硅焊丝作为焊缝填充金属对AZ31镁合金和6061铝合金进行对接，焊接过程稳定，焊缝成型良好。利用光学显微镜、扫描电镜、能谱和X射线衍射等表征方法，对接头的组织、成分和相组成等进行了分析。结果表明：填充金属与铝母材界面结合良好，与镁母材联生结晶，晶粒长大形成均匀分布的柱状晶，为a镁基固溶体和γ（Mg17Al12）的共晶组织，镁侧熔合区生成TMgl7Al12、Mg2A13、Mg2Si金属间化合物。力学性能测试表明：镁侧熔合区的显微硬度值较高，该处生成了脆硬的金属间化合物；断裂均发生在镁侧熔合区，属于脆性断裂。断裂的主要原因是镁侧熔合区生成了大量的Mg2Si、Mgl7Al12和Mg2Al3金属间化合物。

英文摘要：

AZ31B magnesium alloy and 6061 aluminum alloy were joined in stable welding process by cold metal transfer welding with ER4043 as filler metal. The microstructure, morphology and phase composition of the welded joints were studied by OM, SEM, EDX and XRD. The results show that weld metal and aluminum substrate are combined with a good interface, while weld metal and Mg substrate are combined with a epitaxial solidification area where the intermetallic compounds of Mg2Al3, MgjTAl12 and Mg2Si are generated. The micro-hardness distribution shows a decreasing trend from Mg side to Al side in the weld. The joint is brittle fractured in the fusion zone of Mg side, where plenty of Mg2Si, Mg2Al3 and Mg17Al12 are distributed continuously.