More accurate local approximations to vacancy formation and diffusion activation enthalpies, and the simulation methods needed to implement them, were introduced. The accuracy of the approximations was assessed by comparison with full atomistic studies for the case of vacancies around a Lomer dislocation in Al. The results showed that the local and linear approximations to the vacancy formation enthalpy and diffusion activation enthalpy were accurate to within 0.05eV outside of a radius of about 13Å (local) and 17Å (linear) from the center of the dislocation core or, more generally, for a strain gradient of up to 6 x 106 and 3 x 106/m, respectively. The results provided a basis for the development of multi-scale models of diffusion under highly non-uniform stresses.

Modelling Diffusion in Crystals under High Internal Stress Gradients. D.L.Olmsted, R.Phillips, W.A.Curtin: Modelling and Simulation in Materials Science and Engineering, 2004, 12[5], 781-97