Investigation of the Stability of CuIn2in Cu-In Phase Diagram

In this study, the stability of the CuIn2 at low temperature and its peritectoid temperature were determined by diffusion couple and phase equilibria experiments. Diffusion couple samples are first fabricated by electroplating In on the Cu substrate and then underwent aging at 100 and 120 °C to observe the formation of intermetallic compounds. In diffusion couple experiment, both CuIn2 and Cu11In9 were discovered at the interface after 100 °C aging. However, only Cu11In9 remained after 120 °C aging. In phase equilibria experiment, 3Cu-97In alloy was found to equilibrate as In + CuIn2 at 100 °C and In + Cu11In9 at 120 °C, which is consistent with the result of diffusion couple. The peritectoid temperature of Cu11In9 +In → CuIn2 reaction is determined to be 110 ± 10 °C. Finally, a revised Cu-In phase diagram calculated by the optimized thermodynamic parameters was given.