Effect of Cu[sbnd]Ce alloy addition on the microstructure and mechanical performance of brazed diamonds with Ni[sbnd]Cr alloy

Abstract

This study was aimed to reduce unwanted thermal damage to diamond grains during brazing. To achieve this goal, the diamonds were brazed using NiCr alloy with the addition of CuCe alloy (i.e. NiCr composite solder). Surface morphology and interfacial microstructure of the brazed samples using NiCr composite solder was characterized. The thermally induced residual stresses of brazed diamond grains were examined by Raman spectroscopy. The static pressure strength and impact toughness of the brazed diamond grains were examined. Constitutional phases of NiCr composite solder after brazing were detected. The results show that the thermal residual stresses values of the brazed diamond grains using NiCr composite solder, in which 2 wt% and 5 wt% CuCe alloy were used respectively, were decreased by 6.4% and 9.7% respectively, meanwhile, the static pressure strength values increased by 4.9% and 13.4% respectively as well as impact toughness values increased by 4.0% and 9.2% respectively, compared with that of the brazed diamond grains using NiCr alloy. Chromium carbides (Cr3C2 and Cr7C3) were obtained at the bonding interface between diamonds and composite solder. The constitutional phases containing Ce2Ni7, which could be beneficial to reduce the thermal damage, were formed in the solder alloy after brazing.