Stability of B1-type oxides in BCC iron by density functional theory calculations

The residence time of the fuel subassembly and hence the achievable fuel burn up is limited by either the void swelling of the wrapper or creep strength of clad. Since fuel cycle cost is strongly linked with burn up, selection of materials resistant to void swelling and irradiation creep is very important. Austenitic stainless steels could not be employed for doses above 120 dpa as their void swelling is detrimental. Temper embrittlement in ferritic steels, associated with segregation of impurities to grain boundaries and consequent weakening, poses a serious limitation in its successful employment at low temperatures. Oxide dispersion strengthened (ODS) steels is an alternative with the advantage of ferritic martensitic steel with respect to high swelling resistance and the potential to push operating temperature to 923 K and beyond from creep strength consideration. The main conclusions from this work are that oxides, namely YO, CdO, SnO, MgO, ScO, ZrO, SiO, AlO, MnO, TaO and ZnO with endothermic formation energy in the iron matrix combined with better bulk moduli, have the potential to improve the properties of ODS steels. B1-type MO oxides retain/improve the bulk modulus of iron matrix better compared to A₂B₂O₇ pyrochlores. AlO, CrO, MoO, TaO, WO and ReO dispersions are predicted to enhance the bulk moduli of the iron matrix and remain structurally intact though they are not observed experimentally. This indicates that the iron matrix confine these oxides to remain intact