Neutron irradiation-enhanced grain growth in tungsten and tungsten alloys

To understand the microstructural stability of candidate plasma-facing materials under fusion-relevantenvironments, neutron irradiation of W and W-3%Re alloys with and without K and La dopants was performed in the mixed-spectrum High Flux Isotope Reactor at nominal temperatures of similar to 850 degrees C and similar to 1100 degrees C to calculated doses between 0.42 and 0.47 dpa. To the best of our knowledge, this study presents the first experimental evidence of radiation-enhanced recrystallization in W and undoped W-Re alloys at similar to 850 degrees C,conditions where thermal annealing does not cause any grain growth in a similar timescale. Potassium- orlanthanum-doped tungsten alloys showed more resistance to radiation-enhanced grain growth. We explain the acceleration of grain growth by analyzing the self-diffusion constant under atomic displacement environments.The microstructural observations of the studied W variants suggest that La doping is more effective than K doping for mitigating recrystallization. This study also found that radiation-enhanced re-crystallization is an important consideration when designing and applying W to plasma-facing components in future nuclear fusion reactors. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study provides experimental evidence of radiation-enhanced recrystallization in tungsten and undoped tungsten-rhenium alloys under fusion-relevant environments. It is found that potassium or lanthanum doping in tungsten alloys improves resistance to radiation-enhanced grain growth. The study also highlights the importance of considering radiation-enhanced recrystallization in the design and application of tungsten plasma-facing components in future nuclear fusion reactors.