期刊
ACTA MATERIALIA
卷 185, 期 -, 页码 181-192出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2019.11.049
关键词
Multilayers; Twin boundaries; Stacking faults; Phase transformation; Molecular dynamic simulations
资金
- NSF [DMR 1642759]
- NSFDMR [1508484]
- DOE-OBES [DE-SC0016337]
- U.S. Office of Naval Research [N00014-17-1-2087]
- Core facility for Advanced Computing and Data Science at the University of Houston
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [1508484] Funding Source: National Science Foundation
Deformation mechanisms governing the strength of nanostructured metallic multilayers have been studied extensively. In general, size effect is the most effective way to tailor the mechanical strength of multilayers. Here we report that three Cu/Co multilayer systems with identical layer thickness but different types of layer interfaces exhibit drastically different mechanical behavior. In situ micropillar compression tests inside a scanning electron microscope show that coherent FCC (100) and (110) Cu/Co multilayer systems have low yield strength of about 600 MPa, and prominent shear instability. In contrast, the incoherent Cu/ HCP Co multilayers show much greater yield strength, exceeding 2.4 GPa, and significant plasticity manifested by a cap on the deformed pillar. Molecular dynamics simulations reveal an unexpected interplay among pre-existing twin boundaries in Cu, stacking faults in HCP Co, and incoherent layer interfaces, which leads to partial dislocation dominated high strength and outstanding plasticity. This study provides fresh insights for the design of strong, deformable nanocomposites by using a defect network consisting of twin boundaries, stacking faults and layer interfaces. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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