Characterization of Al/Ni multilayers and their application in diffusion bonding of TiAl to TiC cermet

Abstract The Al/Ni multilayers were characterized and diffusion bonding of TiAl intermetallics to TiC cermets was carried out using the multilayers. The microstructure of Al/Ni multilayers and TiAl/TiC cermet joint was investigated. The layered structures consisting of a Ni3(AlTi) layer, a Ni2AlTi layer, a (Ni,Al,Ti) layer and a Ni diffusion layer were observed from the interlayer to the TiAl substrate. Only one AlNi3 layer formed at the multilayer/TiC cermet interface. The reaction behaviour of Al/Ni multilayers was characterized by means of differential scanning calorimeter (DSC) and X-ray diffraction. The initial exothermic peak of the DSC curve was formed due to the formation of Al3Ni and Al3Ni2 phases. The reaction sequence of the Al/Ni multilayers was Al3Ni → Al3Ni2 → AlNi → AlNi3 and the final products were AlNi and AlNi3 phases. The shear strength of the joint was tested and the experimental results suggested that the application of Al/Ni multilayers improved the joining quality.