Effect of heat treatment on helium trapping in vanadium alloy at high ion implantation fluence

Helium was implanted into a V-4Ti alloy by using a 5 keV helium ion beam with a flux of 1014 He/cm2 s, and then helium retention was analyzed by a technique of thermal desorption spectroscopy (TDS). The influence of heat treatment on helium trapping was studied by pre-annealing of the samples before ion irradiation. The annealing temperature was 973, 1223 and 1373 K, respectively. Results indicated that pre-annealing treatments did not influence significantly the helium retention and release behavior in vanadium alloy on the present experimental conditions where the helium ion implantation fluence is in the region of 1017-1018 He/cm2, which shows a different tendency from the situation at a low fluence region (1013-1014 He/cm2). The reason could be due to different trap mechanisms of helium at different ion fluences