Reaction-assisted diffusion bonding of Ti6Al4V alloys with Ti/Ni nanostructured multilayers

The Ti and Ni alternating layers were deposited onto the base materials by magnetron sputtering. Ti/Ni multilayers with different stoichiometries of Ti and Ni were investigated. The joining processes were performed at 800 °C for 60 min under pressure of 5-15 MPa. The microstructures of the interface and the mechanical performances were assessed. Reliable joints can be obtained successfully with all three multilayers with different Ti/Ni ratios. A higher pressure and higher Ni content in the multilayers contributed to a higher shear strength. The highest shear strength of 160 MPa was achieved for the joint under 15 MPa using Ti/Ni multilayers with the stoichiometry ratio of Ti/Ni of 1:3, the hardness of the joint was 6.9 GPa. The intermediate phases appeared to be combinations of hard intermetallics frequently occurred in the Ti-Ni binary system.