Effect of Nd element on the microstructure and mechanical performance of brazed diamonds with Ni–Cr filler metal

To achieve the brazed diamond tools with low thermal damage, the diamonds were brazed using Ni–Cr base filler metals containing up to 1.5 weight percent Nd. The microstructure of Ni–Cr base filler metals and the surface morphology and interfacial microstructure of brazed samples were characterized. The results show that by the addition of Nd, the microstructure of filler metals is obviously refined and becomes uniform. Meanwhile, Nd doping effectively reduces the graphitization degree and thermal residual stress of brazed diamonds. In addition, a variety of carbides (such as Cr₃C₂, Cr₇C₃, and SiC) which have low hot cracking tendencies are formed through occurring chemical/metallurgical reactions. The microstructural NdNi₄B particles contribute to reducing the thermal damage of the brazed diamonds after brazing. At a doping level of 1.0 wt.% of rare-earth Nd, the maximum residual stress of brazed diamond was reduced by 20% and the material removal increased by 45.1%.