Role of refractory metal alloys in fusion reactor applications

The role of the refractory metal alloys in relation to their possible application for future thermonuclear fusion reactor systems is considered. Assessment of the availability and properties of the refractory metals indicates that alloys of vanadium, niobium and molybdenum are most likely to play a major role in reactor systems. The operating environment of a fusion reactor and the materials constraints that are imposed by radiation damage effects and plasma-wall interactions are considered briefly. The metallurgical aspects of the refractory metals and their alloys are then reviewed with a subsequent assessment of the existing database on the effects of neutron and ion irradiation on physical and mechanical properties. Consideration is also given to the effect of specific environments on alloy properties and to the industrial base and availability of refractory metal alloys. The review concludes with a brief summary in which it is proposed that alloys based on vanadium offer the best potential for long-term fusion reactor applications for reasons of low induced radioactivity and good structural stability under irradiation. It is further concluded that the current database for vanadium alloys is inadequate in respect of fusion reactor design, safety and environmental requirements and that extensive research will be necessary if the potential of these alloys is to be realized. (Auth.)