Dissimilar Joining of Immiscible Fe-Mg using Solid Metal Dealloying

Joining of Mg alloy to steel has received wide attention for design of multi-materials. This letter describes joining of immiscible pure iron and pure magnesium (Fe-Mg), as a simplified model, performed by solid metal deal-loying (SMD) between Mg and Fe100_xNix interlayers that were preliminary joined to the Fe part by diffusion bonding. SMD formed an Fe-Mg bicontinuous composite with interconnected morphology at the Fe-Mg weld interface. The effect of Ni composition x in the interlayer on the weld strength was examined. Strong joints were obtained when 30 < x < 50 at.%, which caused Mg base-metal fracture due to a well-interconnected Fe-Mg structure. When too little (x < 30 at.%) or too much (x > 60 at.%) Ni was added, interfacial fracture occurred due to limited dealloying reaction and formation of an isolated Fe product surrounded by a large amount of brittle Mg2Ni.

Automated summary

This letter investigates the joining of immiscible pure iron and pure magnesium using solid metal deal-loying. The Fe-Mg bicontinuous composite was formed at the weld interface by diffusion bonding and SMD. The Ni composition in the interlayer greatly influenced the weld strength, with optimal results obtained at 30 < x < 50 at.%.