Dissimilar joining of Ti-6Al-4 V with ZK60 and AZ31 by eutectic-melting-induced liquid metal dealloying

• Dissimilar commercial alloys joined for the first time via dealloying. • Ti and Mg alloys joined via bicontinuous structure without intermetallic layers. • Dealloying based joining enabled dissimilar joint with 3% ductility. • Minor alloying elements can inhibit dealloying-based joining process. Ti-6Al-4V and Mg alloys (ZK60 and AZ31) were successfully joined using a dealloying-based method. The interfacial microstructure and mechanical properties of joints were characterized by scanning electron microscopy, scanning-transmission electron microscopy, energy-dispersive X-ray analysis, indentation testing, and tensile testing. When ZK60 was butt-joined to a Ti-Cu interlayer pre-diffusion bonded to the Ti alloy and heated under pressure, eutectic-melting-induced liquid metal dealloying (EMI-LMD) occurred at the interface. This process led to the formation of a bicontinuous Ti/Mg microstructure, resulting in robust mechanical joining between the dissimilar alloys. Specific minor elements in the Mg alloy significantly influenced the occurrence of dealloying. Dealloying did not occur between the Ti-Cu interlayer and AZ31 due to the formation of an Al-rich diffusion barrier. To address this issue, dealloying-based joining was achieved by inserting ZK60 between the Ti-Cu interlayer and AZ31. EMI-LMD induced a concentration gradient of minor elements in the Mg alloy, which affected the joint properties. This study is the first to demonstrate that the EMI-LMD joining method can be applied to joining dissimilar commercial alloys.