Chemical diffusion coefficients in solid Mg-rich lithium-magnesium alloys

The concentration galvanic cell method was used in measurements of the equi librium electromotive forces and in the galvanostatic experiments of the in terdiffusion coefficient in the solid Mg-rich Li-Mg alloys at 578 K, 783 K and 860 K. It has been found that the calculated excess Gibbs free energies of Li show negative deviations from the ideal solutions and that the minim al values do not exceed -11 kJ/mol. The measured chemical diffusion coeffic ients were described by the D a r k e n ' s relation, and the self-diffusio n coefficient of Li was calculated. Next, the A r r h e n i u s equation wa s worked out. The obtained value of the activation energy is equal to 69.09 kJ/mol. It is close to that predicted from the empirical relation describi ng the dependence of the activation energy on the melting temperature of me tal.