Interfacial characteristics and elevated temperature wear behavior of WC_P-NiCrBSi/refractory steel composite

WC_P-NiCrBSi/refractory steel composite was fabricated by vacuum fusion sintering. The composite was constructed with rod-like WC_P-NiCrBSi array within refractory steel matrix. This composite material structure could realize well compromise between hardness and toughness. The microstructures of the composite interface and WC_P-NiCrBSi reinforcement were characterized using SEM, EDS and microhardness. The elevated temperature wear behavior of the composite was evaluated on ring-on-disc wear tester and compared with the unreinforced refractory steel. The results show that a metallurgical binding free from cracks and pores is produced between the refractory steel matrix and the WC_P-NiCrBSi reinforcement. γ-Ni solid solution layer adjacent to the WC_P-NiCrBSi reinforcement is formed by isothermal solidification and a large number of fine Fe-Cr-B precipitates are generated in the diffusion affected zone adjacent to the matrix due to mutual diffusion of elements. WC_P are evenly dispersed within the WC_P-NiCrBSi reinforcement and γ-Ni(Ni₃Si), Ni-B, Cr-B and multiple eutectic are formed during the solidification of NiCrBSi alloy. In the temperature range from room temperature to 600℃, the wear resistance of the WC_P-NiCrBSi/refractory composite is better than that of the unreinforced refractory steel. The wear resistance advantage of the composite at room temperature is maximum, and gradually decreases as the temperature increases. At room temperature, the wear mechanism of the composite is mild adhesive wear regime due to WC_P preventing metal to metal contact. WC_P-NiCrBSi/refractory steel the composite exhibits mild oxidation wear at 300℃ and 600℃ owing to the oxide film formation on the worn surface.