Hung, Han TangHan TangHungChang, Fu LingFu LingChangTsai, Chin HaoChin HaoTsaiLiao, Chia YiChia YiLiaoC. ROBERT KAO2023-10-252023-10-252023-09-011996-1944https://scholars.lib.ntu.edu.tw/handle/123456789/636521Indium is considered a candidate low-temperature solder because of its low melting temperature and excellent mechanical properties. However, the solid-state microstructure evolution of In with different substrates has rarely been studied due to the softness of In. To overcome this difficulty, cryogenic broad Ar+ beam ion polishing was used to produce an artifact-free Cu/In interface for observation. In this study, we accomplished phase identification and microstructure investigation at the Cu/In interface after long-term thermal aging. CuIn2 was observed to grow at the Cu/In interface and proved to be a stable phase in the Cu–In binary system. The peritectoid temperature of the Cu11In9 + In → CuIn2 reaction was confirmed to be between 100 and 120 °C. In addition, the growth rate of CuIn2 was discovered to be dominated by the curvature of the reactant Cu11In9/In phase and the temperature difference with the peritectoid temperature. Finally, a comprehensive microstructural evolution mechanism of the Cu/In solid-state interfacial reaction was proposed.enCuIn 2 | In | interfacial reaction | intermetallic compounds | low melting-point solderjournal article10.3390/ma16186263377635412-s2.0-85173013321https://api.elsevier.com/content/abstract/scopus_id/85173013321