THE CONTRIBUTION OF LATERAL MASS-FLOW EFFECTS TO THE COMPENSATION OF UNEQUAL DIFFUSION RATES IN THE GOLD-SILVER SYSTEM

The mass-flows occurring perpendicular to diffusion direction are discussed as a contribution to the compensation for excess-atom and vacancy flows caused by unequal diffusion rates in gold-silver couples. The lateral mass-flow rates have been derived from surface contour profiles that develop during interdiffusion. The excess-atom and vacancy flows have been determined by an evaluation of concentration penetration curves based on known thermodynamic and diffusion data. The measurements reveal that the relative contribution of lateral mass-flows to the compensation process increases with temperature and annealing time. Usually the contribution is in the percentage range but may become appreciable for smaller diameter diffusion couples.