PROPERTIES OF V-4CR-4TI FOR APPLICATION AS FUSION-REACTOR STRUCTURAL COMPONENTS

Vanadium-based alloys are promising candidate materials for applicatio n in fusion reactor first-wall and blanket structures because they off er several important advantages, i.e. inherently low irradiation-induc ed activity, good mechanical properties, good compatibility with lithi um, high thermal conductivity and good resistance to irradiation-induc ed swelling and damage. As part of a program to screen candidate alloy s and develop an optimized vandanium-base alloy, extensive investigati ons of various V-Ti, V-Cr-Ti and V-Ti-Si alloys have been conducted af ter irradiation in lithium in fission reactors. From these investigati ons, V-4wt.%Cr-4wt.%Ti was indentified as the most promising alloy. Th e alloy exhibited attractive mechanical and physical properties that a re prerequisites for first-wall and blanket structures, i.e. high tens ile strength, high ductility, good creep properties, high impact energ y, low ductile-brittle transition temperature before and after irradia tion, excellent resistance to irradiation-induced swelling and microst ructural instability and good resistance to corrosion in lithium. In p articular, the alloy is virtually immune to irradiation-induced embrit tlement, a remarkable property compared with other candidate materials being investigated in the fusion-reactor-materials community. The eff ects of helium, charged dynamically in simulation of realistic fusion reactor conditions, on tensile, ductile-brittle transition and swellin g properties were insignificant. The thermal creep behavior of the all oy was significantly superior to that of austenitic and ferritic/marte nsitic steels.