Enabling Research on oxide dispersion strengthened (ODS) ferritic steels (CfP-WP15-ENR-01/UL-01)

The deuterium-tritium fueled Tokamak reactor is regarded worldwide as the most viable candidate for fusion energy generation. At the same time, the greatest challenge is extremely high temperature of the plasma. So the critical issue is materials performance, especially the components facing the hot plasma. Only a few materials can suite the requirements:  advanced ferritic/martensitic steels, vanadium-based alloys, SiC-fiber reinforced ceramic SiC composites and W alloys. 

In this project, we focus on oxide dispersion strengthened (ODS) ferritic steels, which have a great potential to be used for high-temperature applications with increase of the operational temperature to 650°C and higher. The production of ODS steels is based on the powder metallurgy method based on mechanical alloying (MA) of the steel powder with Y2O3 for several tens of hours and consequent consolidation by hot isostatic pressing (HIP) at temperature around 1000-1200°C and pressure ~100 MPa. 

Oxide nanoparticles impose increase of strength, radiation resistance, and creep resistance at high operation temperatures. The best candidate for oxide nanoparticles up till now is Y2O3, which is stable oxide with high melting temperature.  The nanoparticle structure in the steel is complex, it consists of Y-Ti-O complex with various Y:Ti proportions, often surrounded by Cr shell. Mechanical properties and radiation resistance of ODS steels are strongly affected by a size and distribution of oxide nano-particles, however, the mechanism of oxide particle formation is still unclear. 

In this project, combining experimental (XANES) and theoretical (first principles band structure calculations) methods, we are going to address at what stage of the fabrication process ODS particles are nucleated. This information will shed light on the atomic scale mechanisms of ODS particle formation allowing to find the ways of optimization of fabrication process and material properties for specific applications. 

Responsible persons: Yu. Purans and E.Kotomin