Effect of nano-vanadium nitride on microstructure and properties of sintered Fe-Cu-based diamond composites

Abstract With FeCu30 pre-alloy powder as the main component of the bond, a new type of nano‑vanadium nitride (VN) additive with different concentrations was introduced into Fe-Cu-based diamond composites to investigate the effect of nano-VN on the microstructure and properties of Fe-Cu-based diamond composites. The hardness, relative density, bending strength and wear loss weight of the fabricated specimens were tested, and then the fracture surfaces and worn surfaces of those specimens were analyzed using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results show that the Fe-Cu-based diamond composites with nano-VN addition exhibited an improvement in the mechanical properties, plasticity and wear resistance, which can be attributed to the dispersion strengthening and grain refinement caused by nano-VN. And the nano-VN can also activate sintering, which can significantly improve the wettability of the binder to diamonds, resulting in more binder elements wetting and diffusion on the diamond surface during the sintering process. Besides, the diamond composites showed the best properties with the addition of 2% nano-VN. That is, the bending strength and the HRB hardness of the diamond composites increased by 25% and 20%, respectively, and the wear resistance of the matrix and holding force coefficient of the matrix to diamond were improved significantly. But an excessive amount of nano-VN was detrimental to the mechanical properties of Fe-Cu-based diamond composites.