It was recalled that the evolution of He-defect complexes, especially in the early stages, was not clearly understood; due mainly to the complexity of the He behaviour in the presence of a large number of interstitial impurities (C, N, O, etc.) in V. Thermal He desorption spectrometry was used here to examine the nature and behaviour of the He-defect complexes. The observed desorption peaks were assumed to be associated with vacancy-type defects. In V, most of vacancies were decorated with interstitial impurities, and implanted He produced HenVnX-type defects (X = C, N, O). Desorption peaks at 570, 690 and 940K were attributed to HenOV, HenOV2 and HenOV4, respectively. The prominence of these peaks increased with O concentration. However, some peaks which were independent of impurity concentration were deduced to involve impurity-free defect clusters such as HenVn.

Effects of Interstitial Impurity on Behavior of Helium-Defect Complexes in Vanadium Studied by THDS. N.Nita, K.Miyawaki, H.Matsui: Journal of Nuclear Materials, 2007, 367-370[1], 505-10

Figure 5

Diffusion of T in V-4Cr-4Ti