Interfacial structure of the joints between magnesium alloy and mild steel with nickel as interlayer by hybrid laser-TIG welding

The joint interface of Mg alloy to steel with Ni interlayer was investigated. Comparing with that without any interlayer, the joint shear strength was improved significantly. The characterization of interfaces in the joint with Ni interlayer was analyzed and discussed. The results show that the formation of intermetallic compound Mg2Ni and solid solution of Ni in Fe at the interface altered the bonding mode of joints which contributed to the increase of the tensile shear strength in contrast to the direct joining of Mg alloy to steel. Owing to the addition of Ni interlayer, the conclusion is that the bonding mode of Mg alloy to steel from mechanical bonding to semi-metallurgical joining.