The formation and growth of intermetallic compounds during interdiffusion of Al/Cu bimetals

Abstract

The diffusion couple technology was used to study the formation and growth of intermetallic compounds (IMCs) of Al/Cu bimetals at the temperature range of 480-540 oC for 5-20 h. The interfacial microstructure formed during interdiffusion and the growth kinetics of IMCs are determined. The results show that four different kinds of IMCs (Al2Cu, AlCu, Al2Cu3 and Al4Cu9) were formed at the Al/Cu interface, which is related to the interfacial diffusion reaction and the migration of phase interfaces. The growth of IMCs is mainly controlled by volume diffusion, and follows a parabolic growth kinetics, i.e. L = kt 1/2. Based on the effective heat of formation model and Gibbs free energy change calculation, the Al2Cu is predicted to form first and the formation sequence of the four IMCs is Al2Cu, Al4Cu9, AlCu and Al2Cu3.