Modification of the hydriding kinetics of U-0.2wt.%V alloy using ion implantations

Abstract Uranium metal and U-0.2wt.%V alloy are very sensitive to hydrogen contamination. Prevention of hydride formation, a basic problem, can be approached by modifying the surface characteristics. Implantations of oxygen, nitrogen, carbon and sulphur ions have been tested as a function of dose from 2 × 10 16 to 2 × 10 18 ions cm −2 . The main results are an increase in the induction time, which is multiplied by factors of 20–80 depending on the implanted species, and a change in the nucleation and growth mechanism from instantaneous nucleation (3 × 10 5 nuclei cm −2 , 125 °C, P H2 = 5 kPa) to a pitting attack (from 300 to less than 10 pits cm −2 ) according to the species. Characteristics of the implanted shells have been determined by secondary ion mass spectrometry and X-ray diffraction.