为获得良好的镁铝异种金属焊接接头，采用钨极氩弧焊填加镁铝合金焊丝ER5183、ER5356的方法进行焊接，利用金相显微镜、扫描电镜对两种焊接接头的微观组织对比分析，利用电子探针、能谱仪研究接头的元素分布，利用显微硬度计对两种焊接接头的显微硬度对比分析。结果表明，采用ER5183、ER5356镁铝合金焊丝，接头未形成连续片状金属间化合物层，能够形成良好的焊接接头；采用ER5183焊丝获得焊缝比采用ER5356组织更为致密，脆硬的Mg-Al金属间化合物少；两种焊接接头镁侧熔合区主要组织为α-Mg固溶体+γ-Al12Mg17的共晶组织和晶界析出相γ-Al12Mg17组织；镁侧焊缝区主要为α-Mg固溶体+γ-Al12Mg17的固溶体组织。焊接接头以Mg、Al元素为主，在镁侧熔合区，Mg、Al质量分数保持稳定，镁侧焊缝区，Mg质量分数逐渐降低，Al质量分数逐渐升高，到铝侧焊缝区达到稳定值。适当控制焊丝中Mg的质量分数，使金属间化合物弥散分布，能够改善AZ31镁合金和7005铝合金的焊接性。

Mg/Al dissimilar alloys are successfully joined by gas tungsten arc welding using ER5183、ER5356 welding wire. Microstructure characteristics of the Mg/Al welded joint are analyzed by means of optical microscope and scanning electron microscope, the distribution of elements is studied by means of electron probe micro-analyzer and energy dispersive spectroscopy, microhardness of two joints are compared and analyzed by micro-sclerometer. No continuous intermetallic compound layer is observed in the joint. Joints with sound surface and free of defects are achieved. Grains of the weld seam using ER5183 wire are finer than that using ER5356 wire. There are much fewer Mg-Al brittle intermetallic compounds in the seam using ER5183 wire. The fusion zone in magnesium side is composed of α-Mg+γ-Al12Mg17 eutectic structure and boundary γ-A112Mg17 precipitations. The weld seam near magnesium is mainly composed of α-Mg+γ-A112Mg17 structure. Contents of Mg and Al elements keep stable in the fusion zone in magnesium side. Content of Mg in the weld seam keeps decreasing while content of Al increasing from the magnesium side to the center of the seam, and both reach to a stable value in the weld seam near aluminum. If the content of Mg in the wire is controlled in a proper value, intermetallic compounds would disperse in the weld seam and weldability of Mg AZ31/Al 7005 dissimilar metals could be improved.