Nanostructural characteristics-mediated plastic behavior of Cu/Ag polycrystalline multilayered materials

Q Li and JY Zhang and J Sun and HY Tang and YG Zheng and HF Ye, PHYSICA SCRIPTA, 96, 015701 (2021).

DOI: 10.1088/1402-4896/abc382

For polycrystalline multilayers materials, the typical nanoscale structural characteristics contain grain, twin and hetero interface, which could make collective and remarkable influence on the mechanical property. In this work, taking Cu/Ag polycrystalline multilayers as an example, the coupling effects of grain boundary, twin boundary and hetero interface on the plastic deformation mechanisms are studied using molecular dynamics simulations. The simulation results show that the dominant plastic deformation mechanisms change from dislocation activities for common multilayer material to hetero interfaces sliding when the ratio of material layer thickness to grain size is small enough, leading to a marked decrease of strength. As for the twin boundary, its strengthening effect follows the conventional Hall-Petch relationship when the grain size is larger than the twin thickness. This twin-related strengthening effect becomes weak with the grain size decreases, indicating a competitive relationship between these two characteristic sizes. These findings will shed light on a more comprehensive understanding of size effects on the underlying mechanisms of plastic deformation of polycrystalline multilayers, which provide crucial guidance for the design of novel materials based on polycrystalline multilayers.

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