Low temperature ductility loss and microstructural evolution of vanadium-titanium-chromium-silicon type alloy after helium ion implantation

Vanadium alloy as candidate structural material would be used at temperatur es ranging above 600 degrees C. However, the components might be exposed to low temperature and low neutron flux irradiation during transient operatio n such as start-up and shutdown period of the reactor. Helium generation al so has a possibility to affect the irradiation behavior of the alloy at the low-temperature. Helium effect on loss of ductility at low-temperature neu tron irradiation for vanadium alloy was pointed out from the results of ten sile tests using various combinations of helium charging and neutron irradi ation. it is possible so far that pre-implantation at ambient temperature i ncreases radiation hardening of the vanadium alloy after irradiation at 400 degrees C. From the viewpoint of low-temperature and low-flux irradiation behavior of vanadium alloy, to clarify the helium effect on microstructure evolution, especially small complexes of interstitial impurity and irradiat ion defect is needed.