Ductility and work hardening in nano-sized metallic glasses
In-situ nano-tensile experiments on 70 nm-diameter free-standing electroplated NiP metallic glass nanostructures reveal tensile true strains of ∼18%, an amount comparable to compositionally identical 100 nm-diameter focused ion beam samples and ∼3 times greater than 100 nm-diameter electroplated samples. Simultaneous in-situ observations and stress-strain data during post-elastic deformation reveal necking and work hardening, features uncharacteristic for metallic glasses. The evolution of free volume within molecular dynamics-simulated samples suggests a free surface-mediated relaxation mechanism in nano-sized metallic glasses.
© 2015 AIP Publishing LLC. Received 5 December 2014; accepted 28 January 2015; published online 9 February 2015. The authors acknowledge summer students Boyu Fan and Timothy Tsang for their help with electroplating. The authors gratefully acknowledge the financial support of the U.S. Department of Energy, Office of the Basic Energy Sciences, and NASA's Space Technology Research Grant Programs through JRG's Early Career grant. The authors also acknowledge support and infrastructure provided by the Kavli Nanoscience Institute (KNI) at Caltech. All computations were carried out on the SHC computers (Caltech Center for Advanced Computing Research) provided by the Department of Energy National Nuclear Security Administration PSAAP project at Caltech (DE-FC52-08NA28613) and by the NSF DMR-0520565 CSEM computer cluster. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469. Any opinion, findings, and conclusions or recommendations expressed in the material are those of the authors and do not necessarily reflect the views of the National Science Foundation.
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