Plasma Facing Materials Based on Dispersion Strengthened Tungsten

Plasma facing materials in extreme environment of fusion reactors suffer high temperature corrosion, irradiation damage, and severe fuel retention. Tungsten is currently the main candidate for plasma materials because of its inherent low thermal expansion coefficient, low tritium storage capacity, high radiation resistance, and good corrosion resistance. However, the interaction between plasma and tungsten under deuterium-tritium reaction exhibits such defects as low temperature brittleness, low recrystallization temperature and high toughness-brittle transition temperature, such as pores, vacancies and fatigue cracks, which are difficult to meet the wall loading requirements of future nuclear fusion reactors. At present, the second phase dispersion strengthening has become one of the common methods to improve the performance of tungsten-based plasma facing materials. However, the existence of high heat load and high flux of particles put forward more stringent requirements for the comprehensive performance of dispersion strengthened tungsten-based materials. In recent years, the research on tungsten-based plasma-facing materials in fusion reactor has been mainly focused on three aspects: first, the effect of adding oxide (Y2O3, La2O3, Al2O3, ZrO2) or carbide (TiC, TaC, ZrC) second-phase particles on the microstructure and mechanical properties of tungsten-based materials; second, the hydrogen retention characteristics of dispersion strengthened tungsten based materials; third, the irradiation damage behavior under the action of different particle flows.The research on the mechanical properties of plasma tungsten based materials mainly includes grain size, tensile and compressive strength, recrystallization temperature, toughness brittleness transition temperature and microhardness. The material preparation process and strengthening phase particle content are the two main aspects affecting the mechanical properties of dispersion strengthened tungsten based materials. At present, the preparation methods of particle strengthening phase mainly include powder metallurgy, mechanical alloying, hydrothermal synthesis and wet chemical method, and the relative density and mechanical properties of tungsten based materials prepared by combining with different sintering methods are very different. The uneven dispersion of strengthening phase particles at grain boundaries and in grains, and the irradiation effect of the high-beam particles on the dispersion-strengthened tungsten-based material causes displacement damage, bubbles, fluff in the microstructure and morphology, micro-cracks and other defects will increase the probability of the material capturing hydrogen isotopes. In addition, the fusion reactor plasma irradiation will also cause embrittlement and hardening of the tungsten material, significantly reducing the thermal shock resistance of the material. This paper reviews the effects of carbide or oxide content on the microstructure and mechanical properties of tungsten based plasma-facing materials prepared by different processes, as well as the latest research progress on hydrogen retention characteristics and irradiation damage in dispersion strengthened tungsten based materials at home and abroad, analyzes the key basic problems of dispersion-strengthened tungsten based plasma-facing materials in recent years, and prospects the main development trends of dispersion-strengthened tungsten based materials in the future, which is expected to provide an important reference for the development of tungsten based materials with excellent resistance to high thermal load and irradiation damage. © 2022, Chongqing Wujiu Periodicals Press. All rights reserved.