Oxidation in Iron–Copper and Iron–Phosphorous Binary Alloys: Relating Alloying and Metal-Oxide Crystallography with Oxidation Resistance.

This study showed significant improvements in resistance to oxidation of iron (Fe) with copper (Cu: 0–3.4 weight %) or phosphorous (P: 0–0.12 weight %) alloying. All these binary alloys had bcc ferrite structure and maintained (i) a homo-epitaxy with the oxide (magnetite–Fe₃O₄) phase below 843 K and (ii) a pseudo-epitaxy with pro-eutectoid magnetite > 843 K. The epitaxial growth, in particular, introduced dislocations, residual stress, and misfit strain in the 'thin' (a few hundred nanometer) oxide film. These were stronger for oxides on near ND||<111> Fe grains, but reduced noticeably with an increase in Cu or P content. The reduced epitaxial strain, residual stress and associated dislocations, appeared to correlate with the improved oxidation resistance—relating alloying and metal-oxide crystallography to oxidation resistance in dilute Fe–Cu and Fe–P binary alloys. [ABSTRACT FROM AUTHOR]