Strain rate-dependent tensile response of glassy silicon nanowires studied by accelerated atomistic simulations

YM Zhang and PH Cao and BH Deng and LP Huang and YF Shi, JOURNAL OF APPLIED PHYSICS, 130, 085105 (2021).

DOI: 10.1063/5.0060136

Mechanical properties of glassy nanowires have been intensively investigated recently by both nanomechanical experiments and atomic- level simulations. Unfortunately, there exists a huge gap in the strain rate of the nanomechanical tests between experiments and simulations, which makes it difficult to compare results even for the same material system. Using accelerated atomistic simulations based on a self-learning metabasin escape algorithm, here, we report the tensile mechanical properties of amorphous Stillinger-Weber silicon nanowires with different intrinsic ductility under strain rates ranging from 10(10) to 10(-1)s(-1). It is found that both brittle and ductile glassy silicon nanowires display weakened strength with a decreasing strain rate, in agreement with the cooperative shear model. Moreover, as the strain rate decreases, the amount of plasticity remains unchanged for the brittle nanowires, yet it decreases for the ductile ones. Such deteriorated plasticity in ductile glassy nanowires is caused by enhanced strain localization at low strain rates. Lastly, we show that via the distance matrix of nonaffine displacement, a more hierarchical potential energy landscape is responsible for the higher strain localization propensity in ductile silicon glassy nanowires. Published under an exclusive license by AIP Publishing.

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