Artifact-free microstructures of the Cu–In reaction by using cryogenic broad argon beam ion polishing

Abstract

Metallurgical systems containing substantial amounts of metallic indium have always been very challenging to investigate due to the difficulties involved with sample characterization caused by the substantial softness of indium. Such difficulties are overcome in this study, and artifact-free microstructures are successfully obtained for the first time by using cryogenic broad Ar beam ion polishing for the reactions between Cu and molten indium at 180 ℃. A two-phase layer consisting of Cu11In9 and In forms at the Cu/In interface. The growth of this layer follows parabolic kinetics, indicating that it is a diffusion-controlled process. Within the layer, Cu11In9 islands are larger near the In side than those near the Cu side, suggesting that coarsening of the Cu11In9 islands occurs. During the cooling process after the reaction, large faceted Cu11In9 islands heterogeneously precipitate over the two-phase layer. Simultaneously, nonfaceted Cu11In9 particles homogeneously precipitate within the In phase.