Effect of void morphology on void facilitated plasticity in irradiated Cu/Nb metallic nanolayered composites

Z Yan and ZR Liu and XF Kong and BN Yao and Q An and SM Jiang and RF Zhang and IJ Beyerlein and SJ Zheng, JOURNAL OF NUCLEAR MATERIALS, 558, 153380 (2022).

DOI: 10.1016/j.jnucmat.2021.153380

Voids are common radiation-induced defects in nuclear materials and produce detrimental effects on me-chanical properties. The influence of a pre-existing void on mechanical behavior has been investigated in single crystals, but the effects of void located at bimetal interfaces on the dislocation nucleation mecha-nisms and associated mechanical performance have not been fully studied. Using Cu/Nb metallic nanolay- ered composites (MNCs) as a model system, with atomic-scale simulations, we report on the influence of a pre-existing void at the Cu/Nb interface on dislocation nucleation and deformation behavior. Compared with the void-free system, the size, location and shape of the voids can influence dislocation behavior sig-nificantly, such as the initial nucleation site, the critical nucleation stress, and the preferred slip system. As the size of the faceted void increases from 3 to 4 nm, the dominant mechanism of dislocation nucle-ation changes from a misfit dislocation-assisted localized shear to a void edge-assisted Frank-Read- like mechanism. Also, the location of the faceted void can change the coupled strain field between the void and the misfit dislocation, ultimately affecting the preferred slip system selection. In contrast, the spher-ical void cannot effectively activate the Frank-Read-like dislocation source due to the absence of edges. This work reveals the effects of void morphology on dislocation behavior, and provides an explanation for co-dominated plasticity of bimetal interface and void. (c) 2021 Elsevier B.V. All rights reserved.

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