Microstructure, microhardness and wear resistance of VCp/Fe surface composites fabricated in situ

Abstract The vanadium carbide particles (VC p )/Fe surface composites were in situ fabricated by a technique combining infiltration casting with subsequent heat treatment. The effects of different heat treatment times on the phase evolution, microstructure, microhardness and wear resistance of the composite were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Vickers hardness tester and wear resistance testing instrument, respectively. The results show that only graphite, α-Fe and V 8 C 7 phases dominate in the composite after being heat treated at 1164 °C for 3 h. The amount of V 8 C 7 decreases gradually from the top surface of the composite to the matrix mainly composed of gray cast iron. The average microhardness of the VC p /Fe surface composites varies according to the different reaction zones as follows: 505 HV 0.1 (vanadium plate), 1096 HV 0.1 (composite region), and 235 HV 0.1 (iron matrix). The microhardness of the composite region is four times higher than that of the iron matrix and two times higher than that of the vanadium plate. This is attributed to the formation of vanadium carbide (V 2 C and V 8 C 7 ) crystallites as reinforcement phases within the iron matrix. The VC p /Fe surface composites exhibit a good wear resistance under two-body abrasive wear test.