Microstructural evolution during low-temperature TLP bonding of WC-6Co cemented carbide to AISI 1045 steel using multi-layer of Ni/Cu/In/Cu/Ni

Transient liquid phase (TLP) bonding of WC-6Co cemented carbide to 1045 steel was performed using a selected Ni/Cu/In/Cu/Ni multi-interlayer at low temperature of 650°C for three different holding times of 10, 20, and 30 min. The Cu and Ni layers were electro deposited on the joining surface of both substrates to prepare the interfaces for joining. Then, an indium film with thickness of 5 μm was settled between them as an interlayer to form the Cu-In solid solution via TLP process. For a bonding time of 10 min, isothermal solidification of copper solid solution was incomplete and double-phase microstructure of δ-(Cu) was formed, but it was observed that by prolonging the TLP holding time to 30 min, due to a rather completing of homogenization of the isothermally formed Cu-In solid solution in joint area, the maximum shear strength of 173 MPa was obtained.