期刊
ACTA MATERIALIA
卷 60, 期 9, 页码 3985-3993出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2012.03.018
关键词
Nanowire; Deformation twinning; In situ tension test; Scanning electron microscopy (SEM); Atomistic simulation
资金
- NSF [NSF-DMR 1056293]
- University of Pennsylvania
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [1056293] Funding Source: National Science Foundation
We have performed in situ scanning electron microscopy tensile experiments and molecular dynamics (MD) simulations on nominally defect-free single-crystalline Au nanowhiskers. The room temperature experiments reveal strengths on the order of the ideal strength and plastic strains of up to 12%, a direct result of deformation twinning that governs plastic flow. The in situ and post mortem electron microscopy observations can be divided into two broad classes of deformation morphologies that correlate with distinct stress strain responses. MD simulations show that the mechanism of twin growth can change from layer-by-layer propagation to parallel and accelerated formation of coalescing nanotwins. The transition between mechanisms is caused by the bending moment resulting from the augmented stress state due to the initial twin and the boundary conditions when a twin grows beyond an embryonic state. These distinct manifestations of deformation twinning suggest that nanoscale material behavior can be tailored for high tensile ductility in addition to ultra-high strength. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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