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Citation: V. Borovikov, M.I. Mendelev, and A.H. King (2016), "Effects of stable and unstable stacking fault energy on dislocation nucleation in nano-crystalline metals", Modelling and Simulation in Materials Science and Engineering, 24(8), 85017. DOI: 10.1088/0965-0393/24/8/085017.
Abstract: Dislocation nucleation from grain boundaries (GB) can control plastic deformation in nano-crystalline metals under certain conditions, but little is known about what controls dislocation nucleation, because when data from different materials are compared, the variations of many interacting properties tend to obscure the effects of any single property. In this study, we seek clarification by applying a unique capability of semi-empirical potentials in molecular dynamics simulations: the potentials can be modified such that all significant material properties but one, are kept constant. Using a set of potentials developed to isolate the effects of stacking fault energy, we show that for a given grain boundary, loading orientation and strain rate, the yield stress depends linearly on both the stable and unstable stacking fault energies. The coefficients of proportionality depend on the GB structure and the value of the yield stress is related to the density of the E structural units in the GB. While the impact of the stable stacking fault energy is easy to understand, the unstable stacking fault energy requires more elucidation and we provide a framework for understanding how it affects the nucleation and propagation process.

Notes: Dr. Mendelev noted that this potential was developed in the same manner as 2009--Mendelev-M-I-Kramer-M-J-Ott-R-T-et-al--Cu-Zr, except that the original Cu potential was replaced by MCu31.eam.fs, which has more realistic stable and unstable stacking fault energies. This potential can be used to simulate the plastic deformation in the Cu-Zr amorphous alloys with embedded Cu particles.

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Notes: These files were sent by M.I. Mendelev (Ames Laboratory) on 27 Sept. 2017 and posted with his permission.
Citation: M.I. Mendelev, M.J. Kramer, R.T. Ott, D.J. Sordelet, D. Yagodin, and P. Popel (2009), "Development of suitable interatomic potentials for simulation of liquid and amorphous Cu-Zr alloys", Philosophical Magazine, 89(11), 967-987. DOI: 10.1080/14786430902832773.
Abstract: We present a new semi-empirical potential suitable for molecular dynamics simulations of liquid and amorphous Cu–Zr alloys. To provide input data for developing the potential, new experimental measurements of the structure factors for amorphous Cu64.5Zr35.5 alloy were performed. In this work, we propose a new method to include diffraction data in the potential development procedure, which also includes fitting to first-principles and liquid density and enthalpy of mixing data. To refine the new potential, we used first-principles and liquid enthalpy of mixing data published earlier combined with the densities of liquid Cu64.5Zr35.5 measured over a range of temperatures. We show that the potential predicts a liquid-to-glass transition temperature that agrees reasonably well with experimental data. Finally, we compare the new potential with two previously developed semi-empirical potentials for Cu–Zr alloys and examine their comparative and contrasting descriptions of structure and properties for Cu64.5Zr35.5 liquids and glasses.

Notes: Update 22 Apr. 2009: the reference was added. Update 14 Oct. 2010: the Cu part of this potential is available separately as 2008--Mendelev-M-I-Kramer-M-J-Becker-C-A-Asta-M--Cu.

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Notes: This file was supplied by Mikhail Mendelev on 28 Nov. 2008.
Citation: M.I. Mendelev, D.J. Sordelet, and M.J. Kramer (2007), "Using atomistic computer simulations to analyze x-ray diffraction data from metallic glasses", Journal of Applied Physics, 102(4), 43501. DOI: 10.1063/1.2769157.
Abstract: We propose a method of using atomistic computer simulations to obtain partial pair correlation functions from wide angle diffraction experiments with metallic liquids and their glasses. In this method, a model is first created using a semiempirical interatomic potential and then an additional atomic force is added to improve the agreement with experimental diffraction data. To illustrate this approach, the structure of an amorphous Cu64.5Zr35.5 alloy is highlighted, where we present the results for the semiempirical many-body potential and fitting to x-ray diffraction data. While only x-ray diffraction data were used in the present work, the method can be easily adapted to the case when there are also data from neutron diffraction or even in combination. Moreover, this method can be employed in the case of multicomponent systems when the data of several diffraction experiments can be combined.

Notes: Update 14 Oct. 2010: the Cu part of this potential is available separately as 2008--Mendelev-M-I-Kramer-M-J-Becker-C-A-Asta-M--Cu.

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Notes: This file was supplied by Mikhail Mendelev. Except for comments, this file is equivalent to "CuZr_mm.eam.fs" in the August 22, 2018 LAMMPS distribution.
Date Created: October 5, 2010 | Last updated: June 07, 2019