Effects of feature sizes on Cu/CoCrFeNi polycrystalline metallic multilayers
Tao Fu, Chuanying Li, Xule Li, Hao Hu, Xianghe Peng
Abstract
: The mechanical properties of metal nanolaminates are strongly affected by feature size (the thickness of individual layer, h , and in-plane grain size, d ), as well as their interplay. In this work, we comparatively investigated the effects of h and d on the mechanical properties of Cu/CoCrFeNi nanolayered polycrystalline metal multilayers (NPMMs) under uniaxial compression using molecular dynamics simulations. The results showed that reducing h significantly increases the flow stress of NPMMs. In contrast, the effect of decreasing d on flow stress depends on h : for smaller (1∼2 nm) and larger (5∼10 nm) h , the flow stress increases and then decreases with decreasing d ; while for moderate h (2∼5 nm), d has an insignificant effect on the flow stress. This indicates a pronounced coupling effect between d and h . Furthermore, the exploration of the deformation mechanisms of the coherent twin Cu/CoCrFeNi NPMMs and the coupling effect also showed that: for larger and smaller h , grain boundaries exhibit a strong hindering effect on dislocation motion; while for moderate h , such hindering effect is weak. Based on the confined layer slip theory, interface barrier strength model, Hall-Petch and Inverse Hall-Petch models, a theoretical model was suggested for quantitatively describing the flow stress of coherent twin Cu/CoCrFeNi NPMMs with different d and h . The results presented would be of great significance for the development of Cu/HEA nanolaminates.