Effect of surface deformation on biocompatibility of biomedical alloys

In this study, biocompatibility of Co-29Cr-5Mo (CCM), 316L steel (316L) and Ti-6Al-4V (TC4) alloys after surface plastic deformation under the condition comparable to the human ankle activities were investigated in details. Biocompatibility of all alloys decreases after surface deformation, while it is most significantly observed in CCM alloy. The different responses of biocompatibility are related to the corresponding microstructure evolution during surface deformation: martensitic phase transformation, dislocation slipping and mechanical twinning in CCM alloy result in the extremely localized microstructure, giving rise to the obviously decreased corrosion resistance or biocompatibility; quite homogenous microstructure after surface deformation leads to the slightly decreased corrosion resistance or biocompatibility in both 316L and TC4 alloys, since the surface deformation is dominated by slipping in 316L and by both slipping and a few mechanical twinning in TC4.