Diffusion and marker experiments for the newly discovered CuIn2 compound

Abstract

Herein, CuIn2 is not identified as a stable phase in the CuIn binary phase diagram. However, several studies have reported the existence of CuIn2 at low temperatures. In this study, an electroplating process was used to examine the solid-state interfacial reactions between indium and copper. An indium layer with a thickness of 50 μm was electroplated onto a 1 mm thick Cu substrate at 25 °C, and the resultant Cu/In diffusion couples were subjected to aging processes at 60 °C, 80 °C, 100 °C, and 120 °C for up to 1000 h. These findings indicate that both CuIn2 and Cu11In9 phases were formed at 60 °C, 80 °C, and 100 °C, whereas only the Cu11In9 phase was detected at 120 °C. The growth kinetics of the Cu/In intermetallic compounds adhered to a parabolic law, implying that the reactions were governed by diffusion-controlled mechanisms. The utilization of a Ta diffusion marker in the experiments revealed that indium acts as the predominant diffusing species within the CuIn2 intermetallic compound.