AbstractActivation energies for impurity diffusion in solids are discussed. New approaches based on elasticity are outlined to predict values of activation energy from the atomic size, surface energy, and elastic modulus of the matrix and impurity. The activation energy for self-diffusion in the matrix must also be known. It is shown that reasonable agreement between the theoretical and experimental values of activation energy are obtained for copper, aluminium, nickel, and iron matrices. The elastic strain energy model is extended to facilitate predictions of vacancy–impurity binding energies. Again good agreement between experiment and theory is obtained, except in the case of aluminium matrices.MST/211