Speaker
Description
Tungsten (W) is the leading candidate for plasma-facing components in future magnetic confinement fusion reactors due to its high melting point, low fuel retention, excellent thermal conductivity, etc. However, the elevated operating temperatures, high neutron flux and plasma flux expected in devices such as ITER, BEST, and DEMO can accelerate recrystallization, leading to grain boundary embrittlement, a higher ductile-to-brittle transition temperature, and mechanical softening. Understanding how irradiation influences the intrinsic recrystallization behavior of tungsten has therefore become a central challenge in predicting material lifetime and designing microstructures with improved stability.
Existing experimental and modeling studies provide essential but limited insight into the kinetics of irradiation-affected recrystallization. Irradiation introduces point defects, voids, dislocation loops, and transmutation products that can simultaneously act as recrystallization drivers and inhibitors. On the one hand, defect accumulation increases stored energy and promotes diffusivity, lowering the onset temperature for recrystallization; on the other hand, the segregation of hydrogen isotopes, He, and other transmutation products may retard dislocation and grain boundary mobility. Current efforts reported in the literature span post-irradiation microstructural analyses and annealing experiments, ion-irradiation studies, phase-field modeling, cluster dynamics simulations, and extended Johnson–Mehl–Avrami–Kolmogorov (JMAK) kinetic frameworks. Yet, systematic comparisons remain challenging due to variation in irradiation conditions, flux, thermal histories, and initial microstructure.
In this work, we analyze available experimental and simulation datasets to identify consistent trends governing W recrystallization, with and without irradiation, and to outline potential pathways to enhance microstructure stability. By evaluating defect-induced energy storage, grain boundary mobility suppression, and the influence of alloying strategies, we establish a conceptual kinetic map that highlights the competing mechanisms controlling recrystallization onset and progression.