Intermetallic growth and Kirkendall effect manifestations in Cu/Sn and Au/Sn diffusion couples

Abstract

The Kirkendall-effect induced migration of inert markers during a diffusion-controlled growth of intermetallic compounds in the Cu/Sn and Au/Sn couples at 215 and 180°C were studied. It was shown that the behaviour of markers in the multiphase reaction zones can be rationalized in terms of the Kirkendall velocity construction. Observations on the microstructural features of the product intermetallic layers and the role of the Kirkendall effect in the morphogenesis of the interdiffusion systems are discussed. It was demonstrated that the velocity of markers in a product layer, the appearance of the Kirkendall plane(s), their location(s) and the morphological evolution of the reaction products can also be explained from a purely chemical point of view considering the diffusion-controlled interactions at the interphase interfaces. A representation of the reaction scheme and kinetics of intermetallic growth in each of the two systems is given.