Prediction of Intermetallic Compound Formation Sequences in Pseudo Binary Diffusion Couples: Experimental Examinations for (Sn-<i>x</i>Zn)/Cu (<i>x</i> = 2, 5, 10, 15, 20 and 25 mass%) by a Kinetic Model with Thermodynamic Data Using MDR Diagram

Abstract

A kinetic model based on the principle of maximum degradation rate of the total system free energy, MDR law, using thermodynamic data is applied to (Sn-Zn)/Cu diffusion couples to predict intermetallic compound phases and their order to be formed. According to this model, only £-Cu 5 Zn 8 is predicted to appear when Zn content is less than 10 mass%, while both £-Cu 5 Zn 8 and ¾-CuZn 4 can exist with 10 mass%Zn or more, which was in a good agreement with EPMA and TEM observations of Cu plates dipped into Sn-Zn baths. Therefore, it is concluded that the phase prediction based on the MDR law can also be applied to pseudo binary diffusion systems.