Interfacial bonding mechanism and adhesive transfer of brazed diamond with Ni-based filler alloy: First-principles and experimental perspective

Brazed diamond tools with active filler metals have attracted tremendous attention due to their high interfacial bonding strength, good formability and excellent mechanical performance. However, the intrinsic interfacial bonding mechanism and fracture behavior of metal/diamond remain unclear. Herein, we first investigate the effects of alloying elements Cr, B, and Si on the interfacial bonding strength and adhesive transfer of brazed diamond with Ni–Cr–B–Si filler alloy by first-principles calculations and experiments. The results show that the Cr exhibits a strong embedding ability at Ni/diamond interface relative to B and Si. Among them, the Cr effectively enhances the interfacial bonding strength due to the formation of strong Cr–C bonds and high work of separation of Ni/diamond interface, which is in good agreement with the well crystallized Cr–C carbides experimentally detected at Ni/diamond interface. The tensile simulation of Ni/diamond interface further verifies the strengthening effects of Cr on Ni/diamond interface since the fracture of diamond occurs prior to the debonding of Ni/diamond interface. The analysis of electronic structures indicates that the strong ionic bond interactions between Cr and C atoms at Ni/diamond interface intrinsically dominate the interfacial bonding properties of brazed diamond with Ni-based filler alloy.