CDIHIOSMEA Project

The study innovatively examined a nano oxide dispersion-strengthened (ODS) NiCoFe and NiCoFeCr medium-entropys alloy with nanosized grains to address the challenge of discovering structural materials for high-temperature irradiation applications, such as in advanced nuclear reactors. Dislocations were identified as the primary defect structures. Following irradiation (Ni2+, 580°C), the average dislocation length density increased from ∼2.6×1013m−2 to ∼6.1×1013 m−2, while the mean dislocation length decreased from 249 nm to 104 nm, contributing to a relative irradiation hardening of 25 %. The alloy exhibited no observable irradiation-induced voids. The ODS-NiCoFeCr alloy showed no detectable void formation following irradiation. The volume-averaged dislocation length density remained on the order of ~1014 m−2, and the mean dislocation length showed a slight increase from 89 to 97 nm, with irradiation. Thus, the findings demonstrate the high-temperature radiation resistance of the novel ODS-NiCoFe and ODS-NiCoFeCr alloys. Your Content Goes Here

One of the main objectives of the proposed work is to comprehensively characterize the defect structures in some of the oxide dispersion strengthened (ODS)– medium entropy alloys (MEAs) following high-temperature irradiation. The other objective will establish an effective correlation of the defect structures with irradiation- induced phenomena such as the hardening and swelling. Another crucial objective of the proposed work is to compare ODS-MEAs with single-crystal MEAs and ODS steel and establish the radiation-damage resistance of ODS-MEAs. Also, among the ODS-MEAs best radiation-tolerant material will be identified based on the characterization of defect structures.

The main outcomes of the experiments include comprehensive characterization of the crystal defects in the thin lamellae of various ODS-CSAs such as the ODS-NiCoFe, ODS-NiCoFeCr, and ODS-NiCoCr taken from irradiated regions. The investigations were performed along the irradiation depth to identify the variation of the defect characteristics with the variation in irradiation dose along the depth by using scanning/transmission electron microscopy (S/TEM)technique. In NiCoFe and ODS-NiCoFe, primary defect strucures were idetified to be dislocations, which contributed to irradiation hardening. In contrast, no observable irradiation voids were observed, indicating swelling resistance of the alloys. In case of ODS-NiCoFeCr, no observable irradiation-induced dislocatins and voids were observed, indicating hardening and swelling resistance of the alloy.