Name the corrosion resistant metals

Most of the corrosion resistant metals or alloys used for implants have a layer of oxides on their surface. The thin (approximately 5 nm) layer on the surface of titanium is amorphous, becoming crystalline if further oxidation and thickening occurs. Ti-6Al-4V has similar thickness, mixed oxide amorphous films in which the composition depends on the treatment (e.g., V is only visible in surface spectra of passivated Ti alloy specimens, whereas in non passivated specimens the surface layer is Al rich), in addition to the main elements, impurities typically present include Ca, P, Si, Cl, S, Na and F.