Anish Ranjan

Oxide dispersion-strengthened (ODS) alloys are a critical class of structural materials for extreme environments, owing to their unique combination of high-temperature strength, thermal stability, and radiation tolerance, enabled by a very high density of nanoscale oxide dispersoids. These features make ODS alloys attractive for advanced nuclear systems, aerospace applications, and other harsh-service conditions where conventional alloys rapidly degrade. Despite decades of development, key challenges remain in understanding how nanoscale oxides interact with matrix microstructures, alloy chemistry, and irradiation-induced defects to control macroscopic performance. This review provides a focused, mechanism-based synthesis of the microstructural features that govern the properties of ODS alloys. Emphasis is placed on grain structure evolution, dispersoid size and distribution, matrix–particle interfaces, and the role of alloying elements in stabilizing oxide nanoparticles and controlling phase composition. Distinctions between ferritic, ferritic–martensitic, and austenitic ODS systems are discussed where relevant, highlighting how microstructural differences influence strengthening mechanisms, creep resistance, and thermal stability. The relationships between microstructure and properties are critically examined, including room- and elevated-temperature mechanical behavior, and long-term thermal stability. Particular attention is given to how dispersoid characteristics and grain-boundary structures influence deformation mechanisms, grain-boundary migration, and dispersoid stability during prolonged service. A dedicated section addresses radiation effects in ODS alloys, synthesizing insights from ion- and neutron-irradiation studies. Key phenomena such as defect sink behavior, He and hydrogen trapping, irradiation-induced dispersoid evolution, and changes in mechanical performance are discussed, supported by evidence from advanced characterization techniques, including TEM and atom probe tomography. Challenges associated with simulating neutron damage and predicting long-term irradiation performance are also highlighted. By integrating microstructure, mechanical properties, and irradiation response, this review provides a coherent framework to guide the design and assessment of next-generation ODS alloys for extreme environments.