UCLA

Nuclear fusion energy is a promising future energy source. However, there are still many challenges that are under studying. One big difficulty comes from material engineering: the requirement to develop a material with superior properties including high hardness, high melting temperature, high strength, high resistance to corrosion, creep, radiation, and low He retention. Among all the choices of materials, tungsten is the prime candidate for plasma-facing material in magnetic fusion energy devices due to its high strength and excellent high temperature properties. However, under irradiation, the hardness of tungsten strongly increases and the toughness is largely reduced, which is called irradiation hardening. The hardening is caused by the formation of Re precipitates, which is induced by radiation. In this work, we studied the micro-structural evolution of W and W-Re alloy under irradiation; For this purpose, we applied a bottom-up approach. We started our research on development of an atomic model. Specifically, we extended an Ising model for binary system to including interstitial. The model was verified against several published works. We then studied alloy evolution of W-Re system using various Monte Carlo simulation techniques. The thermodynamics as well as kinetic evolution of W-Re alloy were studied. Finally, we moved onto the continuum scale and study the cluster distribution and irradiation hardening using stochastic dynamics simulations. The cluster dynamics in three creator environments: DEMO, HFIR, and JOYO were simulated and the results were compared with experimental data.