Superplastic Bonding of Electrodeposited Nanocrystalline Ni Alloys

Abstract

Superplastic bonding was performed using electrodeposited Ni and electrodeposited Ni-B to apply to low-temperature diffusion bonding of carbon steel. Electrodeposited Ni and Ni-B were bonded at 450℃ in air and at a strain rate of 1 × 10−4 s−1. The shear test measured the bond strength, and the maximum bond strength of 69 MPa was obtained. Since the obtained bonding strength at 450℃ is comparable to that obtained by diffusion bonding of carbon steel at 0.5Tm, it is possible to decrease the bonding temperature to 0.4Tm by applying this boning process. The bonding strength depended on the amount of strain and increased as the strain increased in the range of strain 0.2 to 0.4. The voids at the interface shrink by superplastic deformation with grain boundary sliding, and the bonded area increases. In the superplastic bonding of electrodeposited Ni alloys, superplastic deformation effectively shrinks voids with a radius of 1-2 µm.