Hybrid diffusive-displacive helium outgassing in Cu/Nb multilayer composites

R Gao and MM Jin and QJ Li and KP So and LF Zhang and XP Wang and QF Fang and C Sun and L Shao and J Li, SCRIPTA MATERIALIA, 194, 113706 (2021).

DOI: 10.1016/j.scriptamat.2020.113706

Gas generation degrades material properties in nuclear applications. The construction of self-assembled bubble channels was proposed to help release gas to the surface. In this study, thermal desorption spectroscopy, in-situ TEM heating and molecular dynamics simulations were carried out to assess the out gassing feasibility in helium- irradiated Cu/Nb multilayers with low structural damage. We found that the formation of outgassing networks has a hybrid diffusive-displacive nature, with diffusive bubble coalescence and crack-induced displacive fracture. The latter could destroy the integrity of the multilayer structure. This suggests that the outgassing strategy making use of self-assembled cavity networks should be carefully designed to avoid large-scale structural failure. (c) 2020 Published by Elsevier Ltd on behalf of Acta Materialia Inc.

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