Determination of optimum ratio of Y₂O₃ : Ti for the ⁹Cr ODS F/M steels for fast breeder reactor clad tube applications

Designing a fast breeder reactor (FBR) demands novel engineering materials with excellent thermo-mechanical as well as irradiation resistant properties. Satisfying the stated criteria, modern ferritic steels are more promising as a reactor-core structural material than the conventional austenitic steels. In addition, ferritic (BCC) steels having excellent neutron irradiation resistance properties that make it the preferred material over FCC-based alloys. Although austenite steels have been serving world-wide as successful core structural materials since a long time, it does not have adequate high-temperature creep strength and void swelling resistance for the prolonged period of service, necessary to achieve higher burn-up of fuel. Therefore, the necessity to develop new advanced materials is critical and unavoidable to maximize the life of FBRs. Based on the structural characteristics of the dispersoid in the model alloy and ⁹Cr ODS steel following conclusions may be drawn such as Milling duration of 60 h resulted in amorphisation of the Y₂O₃ and Ti has no effect on this amorphisation. The amorphous Y₂O₃ is accommodated along the interface of the fragmented nanocrystalline Fe matrix. No chemical dissociation/decomposition of the Y₂O₃ takes place during mechanical milling and the Y-O bonds are intact in the Y₂O₃ molecule