Superplastic Creep of Metal Nanowires From Rate-Dependent Plasticity Transition

Tao, Weiwei; Cao, Penghui; Park, Harold S.

doi:10.1021/acsnano.8b02199

Title: Superplastic Creep of Metal Nanowires From Rate-Dependent Plasticity Transition

Abstract

Understanding the time-dependent mechanical behavior of nanomaterials such as nanowires is essential to predict their reliability in nanomechanical devices. This understanding is typically obtained using creep tests, which are the most fundamental loading mechanism by which the time dependent deformation of materials is characterized. However, due to existing challenges facing both experimentalists and theorists, the time dependent mechanical response of nanowires is not well-understood. Here, we use atomistic simulations that can access experimental time scales to examine the creep of single-crystal face-centered cubic metal (Cu, Ag, Pt) nanowires. Here, we report that both Cu and Ag nanowires show significantly increased ductility and superplasticity under low creep stresses, where the superplasticity is driven by a rate-dependent transition in defect nucleation from twinning to trailing partial dislocations at the micro- or millisecond time scale. The transition in the deformation mechanism also governs a corresponding transition in the stress-dependent creep time at the microsecond (Ag) and millisecond (Cu) time scales. Overall, this work demonstrates the necessity of accessing time scales that far exceed those seen in conventional atomistic modeling for accurate insights into the time-dependent mechanical behavior and properties of nanomaterials.

Authors:

Tao, Weiwei ^[1]; Cao, Penghui ^[2];

^[1]

Boston Univ., MA (United States). Dept. of Mechanical Engineering
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Nuclear Science and Engineering

Publication Date:: 2018-04-30

Research Org.:: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

Sponsoring Org.:: USDOE

OSTI Identifier:: 1435426

Grant/Contract Number:: NE0008450

Resource Type:: Accepted Manuscript

Journal Name:: ACS Nano

Additional Journal Information:: Journal Volume: 12; Journal Issue: 5; Journal ID: ISSN 1936-0851

Publisher:: American Chemical Society (ACS)

Country of Publication:: United States

Language:: English

Subject:: 77 NANOSCIENCE AND NANOTECHNOLOGY; nanowire; superplasticity; creep; rate-dependent deformation; self-learning metabasin escape algorithm

Citation Formats


                    Tao, Weiwei, Cao, Penghui, and Park, Harold S. Superplastic Creep of Metal Nanowires From Rate-Dependent Plasticity Transition.  United States: N. p., 2018. 
Web.  doi:10.1021/acsnano.8b02199.

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                    Tao, Weiwei, Cao, Penghui, & Park, Harold S. Superplastic Creep of Metal Nanowires From Rate-Dependent Plasticity Transition.  United States.  https://doi.org/10.1021/acsnano.8b02199

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                    Tao, Weiwei, Cao, Penghui, and Park, Harold S. Mon .  
"Superplastic Creep of Metal Nanowires From Rate-Dependent Plasticity Transition".  United States.  https://doi.org/10.1021/acsnano.8b02199.  https://www.osti.gov/servlets/purl/1435426.

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@article{osti_1435426,

  title        = {Superplastic Creep of Metal Nanowires From Rate-Dependent Plasticity Transition},

  author       = {Tao, Weiwei and Cao, Penghui and Park, Harold S.},

  abstractNote = {Understanding the time-dependent mechanical behavior of nanomaterials such as nanowires is essential to predict their reliability in nanomechanical devices. This understanding is typically obtained using creep tests, which are the most fundamental loading mechanism by which the time dependent deformation of materials is characterized. However, due to existing challenges facing both experimentalists and theorists, the time dependent mechanical response of nanowires is not well-understood. Here, we use atomistic simulations that can access experimental time scales to examine the creep of single-crystal face-centered cubic metal (Cu, Ag, Pt) nanowires. Here, we report that both Cu and Ag nanowires show significantly increased ductility and superplasticity under low creep stresses, where the superplasticity is driven by a rate-dependent transition in defect nucleation from twinning to trailing partial dislocations at the micro- or millisecond time scale. The transition in the deformation mechanism also governs a corresponding transition in the stress-dependent creep time at the microsecond (Ag) and millisecond (Cu) time scales. Overall, this work demonstrates the necessity of accessing time scales that far exceed those seen in conventional atomistic modeling for accurate insights into the time-dependent mechanical behavior and properties of nanomaterials.},

  doi          = {10.1021/acsnano.8b02199},

  journal      = {ACS Nano},

  number       = 5,

  volume       = 12,

  place        = {United States},

  year         = {2018},

  month        = {4}

}

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https://doi.org/10.1021/acsnano.8b02199

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Figures / Tables:

Figure 1.: Representative creep curve (strain ε vs time) for a Cu nanowire subject to a creep stress of 0.59σ_y at room temperature using the SLME approach.

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