For tungsten in divertor parts of future fusion reactors, a fine-grained microstructure is preferred to reduce its brittle-to-ductile transition temperature and minimize cracking due to cyclic thermal and mechanical loading. Our ongoing study on warm- and cold-rolled tungsten sheets with different degrees of deformation explores the potential of potassium-doping (K-doping) to stabilize the microstructure at high operation temperatures. Successful production of technically pure and K-doped tungsten sheets rolled equivalently up to very high logarithmic strains of 4.6 was proven accompanied by in-depth analysis of the evolution of microstructure and mechanical properties after the different rolling steps in past publications. The current investigation on the same material batch analyses and discusses the distribution of K-bubbles with increasing rolling strain, their chemical composition by means of advanced nano-scaled EDX analysis, and their influence on microstructural changes of tungsten due to recovery, recrystallization and grain growth in different temperature regimes between 600 °C and 2400 °C.
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