Modelling and Simulation in Materials Science and Engineering

Generalized stacking fault energies for embedded atom FCC metals

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Atomistic calculations for the 〈112〉-generalized stacking fault (GSF) energy curve are performed for various embedded atom models of FCC metals. Models include those by Voter and Chen; Angelo, Moody and Baskes; Oh and Johnson; Mishin and Farkas; and Ercolessi and Adams. The resulting curves show similar characteristics but vary in their agreement with the experimental estimates of the intrinsic stacking fault energy, γsf, and with density functional theory (DFT) calculations of the GSF curve. These curves are used to obtain estimates of the unstable stacking fault energy, γus, a quantity used in a criterion for dislocation nucleation. Curves for nickel and copper models show the theoretically expected skewed sinusoidal shape; however, several of the aluminium models produce an irregularly shaped GSF curve. Copper and aluminium values for γus are underestimates of calculations from DFT, although some of the nickel models produce a value matching one of the available DFT results. Values for γsf are either fitted to, or underestimate, the measured results. For use in simulations, the authors recommend using the Voter and Chen potential for copper, and either the Angelo, Moody and Baskes potential or the Voter and Chen potential for nickel. None of the potentials model aluminium well, indicating the need for a more-advanced empirical potential.