Effects of temperature change on microstructural evolution in vanadium alloys under ion irradiation up to high damage levels

Recently, it has been pointed out that temperature change under irradiation strongly affects the microstructural evolution of materials. From an engineering point of view, it is very important to investigate the effects of temperature change under irradiation up to high damage levels. Ion irradiations were conducted in the High Fluence Irradiation Facility (HIT) up to 25 dpa. Both upward and downward temperature changes were performed with temperature combinations of 350/500 and 500/350 °C. Under irradiation with an upward temperature change, the microstructure in vanadium after the temperature change has been found to approach the microstructure of material irradiated at constant temperature with increasing damage level. On the other hand, significant effects of temperature change appeared in V–4Cr–4Ti–0.1Si at high damage level. Under irradiation with a downward temperature change, coarsening of defects was observed just after the downward temperature change. The microstructure approached the microstructure of the material irradiated at constant temperature with increasing damage level.