Effects of Ce and La elements on interfacial bonding, thermal damage and mechanical performance of brazed diamonds with NiCr filler alloy

Abstract Ni-based filler alloys have become a prevalent choice for brazed diamond tools due to their strong mechanical strength and good wettability to diamond. However, the decrease of diamond strength resulting from thermal damage during brazing process limits the application of Ni-based brazed diamond tools. Herein, the effects of Ce and La elements on interfacial bonding, thermal damage and mechanical performance of brazed diamonds with Ni Cr filler alloy are systematically investigated. The results show that the Ce and La atoms tend to segregate in the interface region close to diamond and promote Cr C bonding. Meanwhile, the Ce and La doped in the interface region can isolate diamond from Ni slab, thereby weakening catalytic effect of Ni on diamond graphitization. According to work of separation Wsep and interface energies γint, the Ce and La are proved to enhance the interfacial bonding strength and thermodynamic stability between diamond and Ni Cr filler alloy. The molecular dynamics simulations further verify inhibition of Ce and La on graphitization of diamond since the damage of diamond structure is restrained in doped interfaces. Moreover, the brazed diamonds with Ce-doped filler alloy exhibit superior mechanical performance, which can be attributed to the reduction in thermal damage of brazed diamonds.