The Effect of Strain on the Stabilization of Oxygen-Enriched Nanoclusters in Fe-Based Alloys...

First-principles theory has been developed to understand the unique material state underlying the ultra stability of O-enriched (with Ti and Y solute additions) nanoclusters (NCs) observed in Fe. We show that an essential condition for stabilizing these NCs is a higher O binding energy on the interface (E_S) than in the interior (E_B) of the NCs. The difference between E_B and E_S is due to the effect of strain, originating from the solute-solute repulsion and the presence of O in the form of O-vacancy pair. The strain is also important in controlling the size of NCs which are predicted to exist only within a narrow O concentration range.