A study was made of the energetics of vacancy formation and diffusion in face-centered cubic cobalt using periodic density functional theory, with and without including surface intrinsic error corrections. The aggregation of vacancies was found to be energetically favourable. The computed vacancy formation energies, with (without) corrections, were 2.34 (1.71)eV for an isolated vacancy and 2.28–1.92 (1.65–1.29)eV/vacancy for 2 to 6 coalesced vacancies. The corrected (uncorrected) diffusion barrier for an isolated vacancy was 1.19 (0.98)eV. It was found that vacancy formation energies were over-predicted for Co, Fe and Ni when surface intrinsic error corrections were made. A study was also made of substitutional W diffusion in Co. Two sequential vacancy-mediated W diffusion mechanisms in Co were identified. Corrected (uncorrected) energy barriers for the steps in these mechanisms lay in the range 1.09–1.44 (0.88–1.23)eV.

First Principles Study of Vacancy and Tungsten Diffusion in FCC Cobalt. M.R.LaBrosse, L.Chen, J.K.Johnson: Modelling and Simulation in Materials Science and Engineering, 2010, 18[1], 015008