Effect of Thermal Gradient on Interfacial Microstructure and Mechanical Properties of WC Particle-Reinforced Steel Matrix Composites

Interface is the focus of composite material research. The interfacial structure of composites is affected by many factors, including particle size, additional elements, and preparation technology. This paper aims to investigate how heat affects the interfacial microstructure and mechanical properties of tungsten carbide particle-reinforced steel matrix composites. In this study, tungsten carbide particles were sealed as porous preforms, and the composites were prepared by casting infiltration method, with molten high-chromium steel filling the preforms. The heat gain of the composite gradually decreased in the infiltration direction from the substrate to the composite surface. The interfacial microstructure and properties of the composites were characterized by scanning electron microscopy, transmission electron microscopy, x-ray diffraction, microhardness test and three-point bending fatigue test. The results revealed that the & alpha;-W2C phase decomposed before the h-WC phase, and the M3W3C carbide increased with the dissolution of tungsten carbide particles. & alpha;-W2C and h-WC were completely decomposed in the high-heating joint surface area, and the interface boundary is clearly visible. With the decrease in heat, h-WC could not be completely decomposed, and a large number of gray rod-like phases of h-WC appeared in the interface. The bonding strength of the composite gradually decreased, and the average Vickers hardness of the interface decreased from 1376 to 855 HV while plasticity increased.

Automated summary

This study investigated the effect of heat on the interfacial microstructure and mechanical properties of tungsten carbide particle-reinforced steel matrix composites. The results showed that with the decrease in heat, the interfacial microstructure changed, the bonding strength decreased, the hardness decreased, but the plasticity increased.