Exploring the trace rare earth Sm on the microstructure and mechanical performance of brazed diamonds by Ni–Cr filler alloy

Abstract

In this study, the properties of Ni-based filler alloy are improved by adding rare earth Sm to them and brazing them at a temperature of 1080 °C. Relevant tests are carried out on filler alloy and brazed joints by means of electron microscopy (SEM), energy spectroscopy (EDS) and X-ray diffractometry (XRD). The results show that the addition of rare earth Sm can refine the grain of the filler alloy, improve the hardness of the filler alloy and reduce the thermal damage of the diamond after welding. The addition of rare earth Sm affects the diffusion of Cr, which reacts with the diamond at the interface to form Cr3C2 and Cr7C3, and the formation of these two carbides improves the bonding strength between the filler alloy and the diamond. When the addition of rare earth Sm is 1.5 wt%, the melting point of the filler alloy is the lowest, the grain refinement is the best, the hardness is the highest, and the thermal damage of the brazed sample is the lowest. In addition, the filler alloy of 1.5 wt%Sm has the greatest effect on the diffusion of the Cr element, the bonding strength between the filler alloy and diamond is the highest, and the mechanical properties of the brazed specimens are the best.

Keywords

• Brazed diamond
• Nickel-chromium filler alloy
• Thermal damage
• Microstructure
• Mechanical properties