Refractory materials for energy applications

The most extensively used refractory metals are tungsten, tantalum, niobium, rhenium, unalloyed molybdenum and its principal alloy, TZM. All of them are characterised by their extremely high melting point above 2000 °C (2273 K) and high hardness at room temperature. They are used in demanding applications that require high-temperature strength and corrosion resistance, for example, wire filaments, casting moulds and chemical reaction vessels in corrosive environments. This contribution is focused on tungsten and new tungsten materials. The intrinsic problems of these materials, that is, their brittleness (even at elevated temperatures), thermal load capacity, heat conductivity, recrystallization, irradiation damage and specific defect processes, such as helium bubbles, swelling, new kinds of surface reactions, crack formation, brittle-to-ductile transition and tritium retention, require the development and assessment of new tungsten materials, and also new fabrication routes and processes.