Evaluation of interface thermal transport of Cu-Graphene nanocomposite under cascade overlaps and its effects on irradiation-induced defects

M Amini and B Azadegan and H Akbarzadeh and R Gharaei, JOURNAL OF NUCLEAR MATERIALS, 567, 153839 (2022).

DOI: 10.1016/j.jnucmat.2022.153839

The materials used in neutron irradiation experiments are typically irradiated up to high doses. Thus, the density of defects in these materials is so high that subsequent collision cascades are overlapping with previously cascade-induced defects. The Cu-Graphene nanocomposite (NC) has been proposed as a high irradiation tolerance material. Its interface region can act as an effective sink to point defects. The interfacial thermal resistance (ITR) and interfacial thermal conductance (ITC) of NC are calculated using non-equilibrium molecular dynamics (NEMD) simulations. Single cascade and cascade overlaps induced by 6 keV primary knocked-on atoms (PKAs) in NC are studied using molecular dynamics (MD) simulations. Results show that Graphene loses its morphology during irradiation. Thus, these phenomena may be the main reason for the reduction and rise of ITC and ITR after the first cascade relative to those of un-irradiated NC, respectively. We found that with increasing the number of cascade overlaps the number of irradiation- induced defects in the upper bulk (bulku) region that cascade ends up in this region of NC increases, but the values of ITR and ITC exhibit a slight fluctuation. By evaluating the effects of increasing the ambient temperature and number of cascades on ITC, and defects in the bulk u region, we found that the suspended carbon chains in Graphene break by irradiation, and the damaged area of Graphene gradually aggravates with increasing the system temperature. Also, at higher temperatures, the number of defects in the bulku region for the cases two and three cascades increases with increasing temperature. These results imply that the damage of Graphene does not destroy the role of the interface region in healing the irradiation-induced defects in the lower bulk (bulkl) region at different temperatures, but can affect thermal transport properties and consequently, change the number of defects in the bulk u region of NC. (C) 2022 Elsevier B.V. All rights reserved.

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