Analytical interatomic bond-order potential for simulations of oxygen defects in iron.

We present an analytical bond-order potential for the Fe-O system, capable of reproducing the basic properties of wüstite as well as the energetics of oxygen impurities in [Formula: see text]-iron. The potential predicts binding energies of various small oxygen-vacancy clusters in [Formula: see text]-iron in good agreement with density functional theory results, and is therefore suitable for simulations of oxygen-based defects in iron. We apply the potential in simulations of the stability and structure of Fe/FeO interfaces and FeO precipitates in iron, and observe that the shape of FeO precipitates can change due to formation of well-defined Fe/FeO interfaces. The interface with crystalline Fe also ensures that the precipitates never become fully amorphous, no matter how small they are.

Atomistic simulations of stainless steels: a many-body potential for the Fe-Cr-C system.

Stainless steels found in real-world applications usually have some C content in the base Fe-Cr alloy, resulting in hard and dislocation-pinning carbides-Fe3C (cementite) and Cr23C6-being present in the finished steel product. The higher complexity of the steel microstructure has implications, for example, for the elastic properties and the evolution of defects such as Frenkel pairs and dislocations. This makes it necessary to re-evaluate the effects of basic radiation phenomena and not simply to rely on results obtained from purely metallic Fe-Cr alloys. In this report, an analytical interatomic potential parameterization in the Abell-Brenner-Tersoff form for the entire Fe-Cr-C system is presented to enable such calculations. The potential reproduces, for example, the lattice parameter(s), formation energies and elastic properties of the principal Fe and Cr carbides (Fe3C, Fe5C2, Fe7C3, Cr3C2, Cr7C3, Cr23C6), the Fe-Cr mixing energy curve, formation energies of simple C point defects in Fe and Cr, and the martensite lattice anisotropy, with fair to excellent agreement with empirical results. Tests of the predictive power of the potential show, for example, that Fe-Cr nanowires and bulk samples become elastically stiffer with increasing Cr and C concentrations. High-concentration nanowires also fracture at shorter relative elongations than wires made of pure Fe. Also, tests with Fe3C inclusions show that these act as obstacles for edge dislocations moving through otherwise pure Fe.

A Be-W interatomic potential.

In this work, an interatomic potential for the beryllium-tungsten system is derived. It is the final piece of a potential puzzle, now containing all possible interactions between the fusion reactor materials beryllium, tungsten and carbon as well as the plasma hydrogen isotopes. The potential is suitable for plasma-wall interaction simulations and can describe the intermetallic Be(2)W and Be(12)W phases. The interaction energy between a Be surface and a W atom, and vice versa, agrees qualitatively with ab initio calculations. The potential can also reasonably describe Be(x)W(y) molecules with x, y = 1, 2, 3, 4.