Additional active metal Nb in Cu–Ni system filler metal for brazing of TiC cermet/steel

•A Nb containing CuNiMn filler metal was devised for the joining of TiC cermet/steel.•Nb was thermodynamically favorable in promoting the TiC/filler interfacial reaction.•Robust metallurgical bonding was achieved by forming Nb2C/Nb6C5/αTi transition zone.•Maximum shear strength of 92.5 MPa was approached.

A Nb containing Cu–Ni–Mn brazing filler was developed for the joining of TiC cermet to steel. Interfacial microstructural investigations of the brazed joint and associated thermodynamic analysis of TiC and niobium carbides were carried out. It was found that Nb was thermodynamically favorable in promoting the decomposition of the TiC, and thus facilitated the TiC/filler interfacial reaction. A transition zone (~5 μm) consisting of Nb2C/Nb6C5/αTi was formed at the filler/TiC interface, indicating a robust metallurgical bonding was achieved. Maximum shear strength of 92.5 MPa was approached, which indicated that the Cu–Ni–Mn–Nb was highly promising for the joining of TiC to steel.