Microstructure, mechanical performance and wear behaviour of MMC (WC-W-Ni/Fe) obtained by infiltration

Abstract

WC-W-Ni-Fe composites were fabricated by infiltrating WC-5 W-5Ni porous preforms with a Cu-10Ni-6Sn binder alloy at 1180 °C. The study focused on the effects of Fe addition on the microstructural evolution and tribological performance of the composites. The infiltration produced dense materials with a heterogeneous microstructure composed of WC and W₂C carbides distributed within a dual-phase metallic matrix consisting of a Cu-rich phase and a NiSn intermetallic compound. The partial dissolution of Fe particles into the binder, enhanced particle rearrangement during solid-state heating, and led to the formation of ring-shaped WC and W distributions. However, both Ni and Fe induced partial decarburization of the carbides and favoured the precipitation of brittle (Fe,Ni)₃W₃C η-phase, preferentially at binder/carbide interfaces and within thermally induced cracks. Tribological testing under dry sliding conditions revealed that Fe-containing composites exhibited improved wear resistance than Fe-free composites, despite the formation of η-phase. The enhancement was attributed to an increased binder ductility and the formation of fracture-induced debris that protected the surface during sliding.