Properties of V4Cr4Ti for application as fusion reactor structural components

Vanadium-based alloys are promising candidate materials for application in fusion reactor first-wall and blanket structures because they offer several important advantages, i.e. inherently low irradiation-induced activity, good mechanical properties, good compatibility with lithium, high thermal conductivity and good resistance to irradiation- induced swelling and damage. As part of a program to screen candidate alloys and develop an optimized vandanium-base alloy, extensive investigations of various VTi, VCrTi and VTiSi alloys have been conducted after irradiation in lithium in fission reactors. From these investigations, V4wt.%Cr4wt.%Ti was indentified as the most promising alloy. The alloy exhibited attractive mechanical and physical properties that are prerequisites for first-wall and blanket structures, i.e. high tensile strength, high ductility, good creep properties, high impact energy, low ductile—brittle transition temperature before and after irradiation, excellent resistance to irradiation-induced swelling and microstructural instability and good resistance to corrosion in lithium. In particular, the alloy is virtually immune to irradiation-induced embrittlement, a remarkable property compared with other candidate materials being investigated in the fusion—reactor—materials community. The effects of helium, charged dynamically in simulation of realistic fusion reactor conditions, on tensile, ductile—brittle transition and swelling properties were insignificant. The thermal creep behavior of the alloy was significantly superior to that of austenitic and ferritic/martensitic steels.