Effect of heat treatment on the bio-corrosion properties and wear resistance of antibacterial Co-29Cr-6Mo-xCu alloys.

Co-Cr-Mo alloys have been widely used in hip implants due to their good corrosion resistance and good wear resistance. However, complaint is still raising due to infection and inflammation. The addition of Cu has been proven to be an effective way to develop a new kind of Co-based alloy with good antibacterial properties. In this paper, the effect of heat treatment on the corrosion property, the tribology property and the antibacterial property of Cu containing Co-based alloys were investigated in detail. The microstructure observation showed that the as-cast alloys mainly consisted of a dendritic matrix with carbide dispersion at grain boundaries and a fine Cu-rich phase in the matrix and at the carbide/matrix interface. The carbide precipitates and the distribution of Cu phases affected significantly the friction coefficient and wear resistance of Co-xCu alloy. Annealing at 1060 °C/24 h promoted the precipitation of carbide and in turn increased the hardness and wear resistance markedly. Heat treatments, including annealing, solid solution and ageing treatment, enhanced the corrosion resistance of Co-xCu alloy without reduction in antibacterial properties. However, the addition of Cu increased the corrosion resistance and antibacterial properties but reduced the wear resistance especially at high Cu content.