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Surface roughness imparts tensile ductility to nanoscale metallic glasses

Adibi, Sara and Branicio, Paulo S. and Liontas, Rachel and Chen, David Z. and Greer, Julia R. and Srolovitz, David J. and Joshi, Shailendra P. (2015) Surface roughness imparts tensile ductility to nanoscale metallic glasses. Extreme Mechanics Letters, 5 . pp. 88-95. ISSN 2352-4316.

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Experiments show an intriguing brittle-to-ductile transition on size reduction on nanoscale metallic glasses (MGs). Here we demonstrate that such phenomena is linked to a fundamental characteristic size effect in the failure mode under tensile loading. Large-scale molecular dynamics simulations reveal that nanoscaled MGs with atomistically smooth surfaces exhibit catastrophic failure via sharp, localized shear band propagation. In contrast, nanosized specimens with surface imperfections exhibit a clear transition from shear banding to necking instability above a critical roughness ratio of  ξ ∼ 1/20, defined as the ratio between the average surface imperfection size and sample diameter. The observed brittle-to-ductile transition that emerges in nanosized MGs deformed at room temperature can be strongly attributed to this roughness argument. In addition, the results suggest that the suppression of brittle failure may be scale-free and be realizable on length scales much beyond those considered here, provided the threshold roughness ratio is exceeded. The fundamental critical roughness ratio demonstrated sheds light on the complex mechanical behavior of amorphous metals and has implications for the application of MGs in nano- and micro-devices.

Item Type:Article
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Greer, Julia R.0000-0002-9675-1508
Additional Information:© 2015 Elsevier Ltd. Received 3 July 2015, Revised 22 August 2015, Accepted 22 August 2015, Available online 28 August 2015.
Subject Keywords:Metallic glasses; Tensile ductility; Brittle-to-ductile transition; Size effect; Surface roughness; Molecular dynamics simulation
Record Number:CaltechAUTHORS:20170711-072842008
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Official Citation:Sara Adibi, Paulo S. Branicio, Rachel Liontas, David Z. Chen, Julia R. Greer, David J. Srolovitz, Shailendra P. Joshi, Surface roughness imparts tensile ductility to nanoscale metallic glasses, Extreme Mechanics Letters, Volume 5, 2015, Pages 88-95, ISSN 2352-4316, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78923
Deposited By: Tony Diaz
Deposited On:11 Jul 2017 22:02
Last Modified:03 Oct 2019 18:13

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