Critical issues and current status of vanadium alloys for fusion energy applications

Vanadium alloys are widely regarded as possessing desirable mechanical and physical properties for application as structural materials in fusion power systems. The bulk of the recent research on vanadium is focussed on ternar ies containing 4-5% Cr and 4-10% Ti. The aim of this paper is to review sig nificant results generated by the international research and development co mmunity on this alloy system and to highlight the critical issues that must be resolved before ahoy development can proceed to the next stage. Recent progress on understanding the physical metallurgy, fabrication and joining behavior, and compatibility with hydrogen and oxygen containing environment s of unirradiated vanadium alloys is discussed. The effect of low-temperatu re neutron irradiation on mechanical properties and their relationship to t he observed microstructure are briefly summarized. Current efforts to chara cterize the high-temperature mechanical properties, develop constitutive eq uations describing flow and fracture, and understand and mitigate the effec ts of non-metallic impurities on properties are presented. (C) 2000 Elsevie r Science B.V. All rights reserved.