  Precipitates in Nickel-based superalloys form during heat treatment on a time
scale inaccessible to direct molecular dynamics simulation, but could be
studied using kinetic Monte Carlo (KMC). This requires reliable values for the
barrier energies separating distinct configurations over the trajectory of the
system. In this study, we validate vacancy migration barriers found with the
Activation-Relaxation Technique nouveau (ARTn) method in partially ordered
Ni$_{75}$Al$_{25}$ with a monovacancy using published potentials for the atomic
interactions against first-principles methods. In a first step, we confirm that
the ARTn barrier energies agree with those determined with the nudged elastic
band (NEB) method. As the number of atoms used in those calculations is too
great for direct ab initio calculations, we then cut the cell size to 255
atoms, thus controlling finite size effects. We then use the plane-wave density
functional theory (DFT) code CASTEP and its inbuilt NEB method in the smaller
cells. This provides us with a continuous validation chain from first
principles to kinetic Monte Carlo simulations with interatomic potentials. We
then evaluate the barrier energies of five further interatomic potentials with
NEB, demonstrating that none yields these with sufficient reliability for KMC
simulations, with some of them failing completely. This is a first step towards
quantifying the errors incurred in KMC simulations of precipitate formation and
evolution.
