Effect of Y on interface characteristics and mechanical properties of brazed diamond with Ni Cr filler alloy

The purpose of this study is to reduce the thermal damage of brazed diamond and improve the mechanical properties of brazed diamond. Herein, composite filler alloys were fabricated by adding reinforced Y into NiCr filler alloy and the brazing diamond specimens were prepared by vacuum brazing using the composite filler alloys at a brazing temperature of 1050 °C for a dwelling time of 5 min. The graphitization degree of brazed diamond was analyzed by Raman spectroscopy, and the hardness and grinding performance of brazed diamond were measured. The results revealed that the introduction of Y reduced the possibility of cracking of the carbonized layer, refined the grain size and thickness of the carbonized layer, and effectively released the thermal stress of the brazed joint. In the brazing process, the filler alloys and diamond were combined chemically and metallurgically to form Cr3C2, Cr7C3 and SiC. In addition, when the addition amount of Y is 0.8 wt%, the exposure of diamond reaches 64.3 % of its own height, and mechanical performance tests confirmed that the hardness and grinding performance of diamond brazed using this filler alloy are higher than those of diamond brazed using pure NiCr alloy. The new NiY compound in the brazed joint is beneficial to reduce the thermal damage of brazed diamond.