Microstructural characterisation of a plasma carburised low carbon Co–Cr alloy

One of the major concerns over long term metal on metal articulations is the carcinogenic effect of metal particles. How to improve the surface hardness and wear resistance of Co–Cr–Mo alloys and thus extend the life span of the metal on metal joint prostheses is a timely task from both a scientific and clinical viewpoint. The present investigation indicated that plasma carburising a Co–Cr alloy between 400 and 600°C can produce a hardened layer on the surface which can significantly improve its wear resistance. Detailed structural, composition and microstructural characterisation have advanced the scientific understanding of the hardening effect. This is the first report that S phase can be formed in Co–Cr alloys during low temperature plasma carburising.