Abstract
Tungsten (W) is a candidate for the plasma facing component material of fusion reactors. During fusion reactor operation, not only displacement damage but also transmutation elements such as rhenium (Re) and osmium (Os) are produced in W by neutron irradiation. To understand the irradiation response of W in a fusion reactor, irradiation effects on hardening, microstructure development and electric resistivity of pure W and W–Re–Os alloys are studied using fission reactor irradiation. In the low-dpa region (<0.4 dpa), irradiation hardening was suppressed by Re addition, but significant hardening appeared in W–26Re alloy after high-dpa (>1 dpa) irradiation. The hardening was caused by the irradiation-induced precipitation of WRe (σ–phase) and WRe3 (χ–phase). Os was more effective in the irradiation hardening than Re owing to the similar irradiation-induced precipitate formation even in low-dpa region. On the bases of these results, the alloy design of W for fusion reactor applications is suggested.
