Effect of silver interlayer on microstructure and mechanical properties of diffusion-bonded Mg–Al joints

The diffusion-bonded Mg–Al joints with and without silver interlayer prepared by Magnetron Sputtering have been investigated. The addition of silver interlayers eliminated the formation of Mg–Al intermetallic compounds and improved the bonding strength of Mg–Al joints. Mg3Ag, MgAg and Ag-based solid solution were observed in the interface of Mg/Ag/Al joint. The microhardness value of the interface in Mg/Ag/Al joint with a maximum value 125 HV of Mg3Ag layer is much lower than that in Mg/Al joint with a maximum value 225 HV of Mg2Al3 layer. Fracture failure in Mg/Ag/Al joint occurred between Mg3Ag layer and MgAg layer. Transgranular fracture and plastic deformation observed on fracture surfaces of Mg/Ag/Al joint differ from cleavage fracture features of Mg/Al joint.

► Silver interlayer prepared by MS was firstly used in diffusion bonding of Mg/Al.
► The addition of silver interlayer avoided the formation of Mg–Al compounds.
► Mechanical properties of Mg–Al joint with silver interlayer were improved.
► Fracture behavior in Mg–Al joint with silver interlayer shows a great difference.