A modified embedded atom method potential for the titanium-oxygen system

WJ Joost and S Ankem and MM Kuklja, MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, 23, 015006 (2015).

DOI: 10.1088/0965-0393/23/1/015006

Small concentrations of impurity atoms can affect the behavior of metal alloys in many ways of interest to the science and engineering community. In some cases, such as for oxygen (O) interstitials and twins or dislocations in titanium (Ti) alloys, these interactions can be difficult to study experimentally due to the small time and length scales of the governing mechanisms. Theory and atomic-scale modeling offers a path toward understanding materials at very high resolution using a variety of techniques ranging from ab initio methods such as density functional theory (DFT) to empirical potential methods such as the Modified Embedded Atom Method (MEAM). In this study we present the first published MEAM potential for the Ti-O system; the potential is fit to experimental measurements and DFT calculations for the lattice constants, elastic constants and thermodynamic characteristics of several Ti-O structures withOconcentration between 0 and 50 at%. We validate the effectiveness of the new potential by successfully reproducing properties such as lattice constants, elastic constants and diffusion energy barriers for other structures. In doing so, we have calculated and report properties for two new stable structures of TiO: a CsCl structure and a zinc blende structure. We also report the first theoretical study on the effects of O concentration on the elastic constants of hexagonal close packed Ti without the confounding effects of changing supercell size. Overall, this new potential will enable interrogation of Ti and O interactions at time and length scales below those available experimentally and above the range accessible by DFT.

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