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Atomistic simulation of tantalum nanoindentation: Effects of indenter diameter, penetration velocity, and interatomic potentials on defect mechanisms and evolution

Ruestes, C. J. and Stukowski, A. and Tang, Y. and Tramontina, D. R. and Erhart, P. and Remington, B. A. and Urbassek, H. M. and Meyers, M. A. and Bringa, E. M. (2014):
Atomistic simulation of tantalum nanoindentation: Effects of indenter diameter, penetration velocity, and interatomic potentials on defect mechanisms and evolution.
In: Materials Science and Engineering: A, Elsevier Science Publishing, pp. 390-403, 613, ISSN 09215093,
[Online-Edition: http://dx.doi.org/10.1016/j.msea.2014.07.001],
[Article]

Abstract

Nanoindentation simulations are a helpful complement to experiments. There is a dearth of nanoindentation simulations for bcc metals, partly due to the lack of computationally efficient and reliable interatomic potentials at large strains. We carry out indentation simulations for bcc tantalum using three different interatomic potentials and present the defect mechanisms responsible for the creation and expansion of the plastic deformation zone: twins are initially formed, giving rise to shear loop expansion and the formation of sequential prismatic loops. The calculated elastic constants as function of pressure as well as stacking fault energy surfaces explain the significant differences found in the defect structures generated for the three potentials investigated in this study. The simulations enable the quantification of total dislocation length and twinning fraction. The indenter velocity is varied and, as expected, the penetration depth for the first pop-in (defect emission) event shows a strain rate sensitivity m in the range of 0.037-0.055. The effect of indenter diameter on the first pop-in is discussed. A new intrinsic length-scale model is presented based on the profile of the residual indentation and geometrically necessary dislocation theory.

Item Type: Article
Erschienen: 2014
Creators: Ruestes, C. J. and Stukowski, A. and Tang, Y. and Tramontina, D. R. and Erhart, P. and Remington, B. A. and Urbassek, H. M. and Meyers, M. A. and Bringa, E. M.
Title: Atomistic simulation of tantalum nanoindentation: Effects of indenter diameter, penetration velocity, and interatomic potentials on defect mechanisms and evolution
Language: English
Abstract:

Nanoindentation simulations are a helpful complement to experiments. There is a dearth of nanoindentation simulations for bcc metals, partly due to the lack of computationally efficient and reliable interatomic potentials at large strains. We carry out indentation simulations for bcc tantalum using three different interatomic potentials and present the defect mechanisms responsible for the creation and expansion of the plastic deformation zone: twins are initially formed, giving rise to shear loop expansion and the formation of sequential prismatic loops. The calculated elastic constants as function of pressure as well as stacking fault energy surfaces explain the significant differences found in the defect structures generated for the three potentials investigated in this study. The simulations enable the quantification of total dislocation length and twinning fraction. The indenter velocity is varied and, as expected, the penetration depth for the first pop-in (defect emission) event shows a strain rate sensitivity m in the range of 0.037-0.055. The effect of indenter diameter on the first pop-in is discussed. A new intrinsic length-scale model is presented based on the profile of the residual indentation and geometrically necessary dislocation theory.

Journal or Publication Title: Materials Science and Engineering: A
Volume: 613
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: MD simulation, Tantalum, Nanoindentation, Plasticity, Twinning
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 02 Mar 2015 09:52
Official URL: http://dx.doi.org/10.1016/j.msea.2014.07.001
Identification Number: doi:10.1016/j.msea.2014.07.001
Funders: C.J.R. and E.M.B. thank support from PICT-PRH-0092 and a SeCTyP grant, as well as valuable discussions with Professor R. Ravelo. , P.E. acknowledges funding from the Swedish Research Council in the form of a Young Researcher grant, the European Research Council via a Marie Curie Career Integration Grant, and the Area of Advance Materials Science at Chalmers., H.M.U. acknowledges funding by the Deutsche Forschungsgemeinschaft via the Sonderforschungsbereich 926., Our appreciation is extended to the UCOP (Grant 09-LR-06-118456-MEXM).
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