High temperature oxidation of bismuth-implanted iron

Bismuth implantation has been shown to reduce drastically the parabolic rate constant of iron oxidation, but only at temperatures below 600 deg C. This result is explained in terms of bismuth segregation blocking fast diffusion paths for transport of Fe ions through iron oxides, while bulk diffusion is unaffected. Complete oxidation inhibition was not observed, contrarily to boron or aluminium implantation. Difference in thermodynamic affinities for implants oxidation can account for this result. (author)