Effect of the saturation conditions and structure on the retention of helium in structural materials

Abstract

A comparison between the kinetics of helium desorption upon linear heating of samples saturated using various regimes is performed, and the effect of dislocations on the retention of helium in materials is estimated. In order to investigate the effect of the conditions of saturation of materials with helium on its retention, samples of austenitic stainless steel 0Kh16N15M3B saturated using various methods were studied, namely, helium irradiation in a cyclotron, in a magnetic mass-separation setup, inside IRT-2000 and BOR-60 reactors, and using the so-called “tritium trick” technique. The investigations show that when saturation of the samples with helium is accompanied by the introduction of radiation defects (in wide limits of helium concentrations and radiation damage), the kinetics of helium evolution from samples of this type is adequate to the kinetics of its evolution from samples irradiated in a reactor. The investigation of the kinetics of helium evolution from the samples of 0Kh16N15M3B steel both after a preliminary deformation and in the process of deformation showed that, in the process of heating, the helium atoms can migrate along dislocation pipes, resulting in a significant effect on the release of helium and its redistribution in the volume of the material. The activation energy for helium pipe diffusion in austenitic steel 0Kh16N15M3B is about 0.7 eV. Mobile dislocations favor the ejection of helium onto the surface of the material, to grain boundaries, interphase interfaces, etc.