Microstructure analysis of W-coated diamond brazing with Ni-Cr active filler

Under vacuum condition of 1 030 ℃ for 20 min, W-coated diamond was heated and brazed with Ni-Cr alloy powder. X-ray diffraction (XRD) was used to analyze the phase changes of W-coated diamond before and after heating. Scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were used to analyze the interface microstructure, the new phase, the morphology and that the element distribution. The results show that the coating phases of W-coated diamond change from W₂C and W before heating to a large amount of WC and a small amount of W₂C after heating, and that the coating does not fall off. After the W-coated diamond is brazed, there forms a small amount of NiW phase formed in the coating and the filler metal, the columnar Cr₇C₃ at the interface of W-coated diamond/Ni-Cr alloy, and the Cr-based intermetallic compound at the interface of steel substrate/Ni-Cr alloy.