Seria: NOMATEN Hybrid Seminar

Prelegent i afiliacja: Dr. Duc Nguyen-Manh; Materials Division, United Kingdom Atomic Energy Authority

Data: March 19, 2024

Miejsce: NOMATEN seminar room / https://meet.goto.com/NCBJmeetings/nomaten-seminar

Streszczenie: 

Microstructural stability of multi-component systems under extreme environment represents one of most challenging issues not only in multi-scale materials modelling but also for developing reliable and advanced engineering components for nuclear material applications. Recently, compositionally complex alloys (CCAs) are designed as novel radiation-resistant materials for future fusion power plants while bcc-W based alloys including SMART (Selfpassivating Metallic Alloys with Reduced Thermal-oxidation) materials are developed at EUROfusion as a safety measure for plasma facing components in case of loss of coolant accident (LOCA). In addition, the microstructural evolution of the single-phase fcc-based CCAs under irradiation suggests that Fe-Cr-Ni-Mn high-entropy alloys are the promising material with potentially good corrosion resistance for nuclear fission systems.

To address these challenges, a new formulation of constrained thermodynamic formalism has been developed to model multi-component alloy system under irradiation for which point defects are being considered as the additional elements in the system [1]. The formalism is represented within matrix formulation via many-body cluster correlation functions which in turn can be computed efficiently from Monte-Carlo simulations in a combination with first principle-based cluster-expansion Hamiltonian. Applying the theory to bcc W-Ta-Cr-V-Hf systems [2], it is predicted that there is a strong enhancement of radiation induced stability in these quinary alloys as well as outstanding radiation resistance in the quaternary W-Ta-Cr-V system, For the latter case, the predictive modelling is an excellent agreement with observation of radiation-induced precipitates observed within Atom Probe Tomography analysis for the specific W38Ta36Cr15V11 alloy composition and irradiated temperature[3]. The similar modelling approach has been recently applied to study the composition stability at finite temperature for the magnetic fcc-based CCAs Fe-Cr-Ni-Mn [4] with a strong swelling resistance as well as for SMART self-passivating alloys W-Cr-Y=Zr as structural materials in DEMO fusion reactors [5]. Finally, I will address some new results from atomistic modelling in predicting microstructure for Tritium retention and permeation in W and its oxides that have an important implication in predicting the important issue of detritiation for the maintenance of fusion engineering material components under waste-treating environment or in accident scenarios.