Influence of carbides and microstructure of CoCrMo alloys on their metallic dissolution resistance

• Corrosion of CoCrMo alloys with different %C and thermal treatments was analysed.
• Passive dissolution rate was controlled by the composition and microstructure.
• Lower %C and thermal treatments improve the corrosion resistance of the alloy.

CoCrMo alloys are passive and biocompatible materials widely used as joint replacements due to their good mechanical properties and corrosion resistance. Electrochemical behaviour of thermal treated CoCrMo alloys with different carbon content in their bulk alloy composition has been analysed. Both the amount of carbides in the CoCrMo alloys and the chemical composition of the simulated body fluid affect the electrochemical properties of these biomedical alloys, thus passive dissolution rate was influenced by the mentioned parameters. Lower percentage of carbon in the chemical composition of the bulk alloy and thermal treatments favour the homogenization of the surface (less amount of carbides), thus increasing the availability of Cr to form the oxide film and improving the corrosion resistance of the alloy.