Molecular Dynamics Simulation of High-Temperature Creep Behavior of Nickel Polycrystalline Nanopillars
Institute for Materials Testing, Materials Science and Strength of Materials, University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart, Germany
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Academic Editors: Tomasz Sadowski, Liviu Marsavina and Nikolaos Michailidis
Molecules 2021, 26(9), 2606; https://doi.org/10.3390/molecules26092606
Received: 8 March 2021
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Revised: 26 April 2021
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Accepted: 26 April 2021
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Published: 29 April 2021
(This article belongs to the Special Issue Metallic and Composite Materials and Structures)
As Nickel (Ni) is the base of important Ni-based superalloys for high-temperature applications, it is important to determine the creep behavior of its nano-polycrystals. The nano-tensile properties and creep behavior of nickel polycrystalline nanopillars are investigated employing molecular dynamics simulations under different temperatures, stresses, and grain sizes. The mechanisms behind the creep behavior are analyzed in detail by calculating the stress exponents, grain boundary exponents, and activation energies. The novel results in this work are summarized in a deformation mechanism map and are in good agreement with Ashby’s experimental results for pure Ni. Through the deformation diagram, dislocation creep dominates the creep process when applying a high stress, while grain boundary sliding prevails at lower stress levels. These two mechanisms could also be coupled together for a low-stress but a high-temperature creep simulation. In this work, the dislocation creep is clearly observed and discussed in detail. Through analyzing the activation energies, vacancy diffusion begins to play an important role in enhancing the grain boundary creep in the creep process when the temperature is above 1000 K.
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Keywords:
polycrystalline nanopillars; molecular dynamics method; creep mechanisms; dislocation creep; grain boundary sliding; deformation map
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MDPI and ACS Style
Xu, X.; Binkele, P.; Verestek, W.; Schmauder, S. Molecular Dynamics Simulation of High-Temperature Creep Behavior of Nickel Polycrystalline Nanopillars. Molecules 2021, 26, 2606. https://doi.org/10.3390/molecules26092606
AMA Style
Xu X, Binkele P, Verestek W, Schmauder S. Molecular Dynamics Simulation of High-Temperature Creep Behavior of Nickel Polycrystalline Nanopillars. Molecules. 2021; 26(9):2606. https://doi.org/10.3390/molecules26092606
Chicago/Turabian StyleXu, Xiang, Peter Binkele, Wolfgang Verestek, and Siegfried Schmauder. 2021. "Molecular Dynamics Simulation of High-Temperature Creep Behavior of Nickel Polycrystalline Nanopillars" Molecules 26, no. 9: 2606. https://doi.org/10.3390/molecules26092606
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