Abstract
A systematic study has been carried out for Nb-Ti wires to investigate the effects of neutron irradiation on Jc's of Nb-Ti wires with a variety of metallurgical structures. The samples used in the present study are Nb-47.8at%Ti (named #A) and Nb-59.8at%Ti (named #B), which are aged at 380°C for 0-104min and irradiated up to 1.3×1018n/cm2 (En>0.1MeV). The Jc's of #A and of #B aged up to 50min are increased by the irradiation. But the Jc's of #B aged longer than 100min are decreased. In these longer aged samples of #B, the presence of Ti enriched precipitates such as alpha and omega phase is estimated from the data of Tc. The Tc's of #A and of #B aged up to 100min are changed little by the irradiation, but the decrease of Tc is observed in #B aged longer than 500min. This decrease indicates that the Ti concentration in the matrix may be increased in terms of radiation induced breakup of the precipitates, and thus causes the reduction in Jc by the irradiation. It is concluded that the superconducting Nb-Ti wire with precipitation enhanced Jc does not appear very resistant to neutron irradiation. Careful consideratiion should be, therefore, stressed in the choice of superconducting wire in its application to fusion reactor magnets.
