Solid/Solid State Interfacial Reactions in the Sn-9Zn/Cu-Based Alloys (C1990 HP, Alloy 25, and C194) Couples

We investigated the kinetics of the intermetallic compound (IMC) growth during the solid/solid state reaction at 125–175°C for 100–2000 h between Sn-9 wt.% Zn (SZ) with Cu-3.28 wt.%Ti (C1990 HP), Cu-2.0 wt.% Be (Alloy 25), and Cu-2.3 wt.% Fe (C194) alloys, respectively. The results revealed that both the CuZn 5 and Cu 5 Zn 8 phases were formed at early stage and the CuZn 5 phase was transformed to the Cu 5 Zn 8 phase when the aging temperature and time were increased in the SZ/C1990 HP couples. The CuZn 5 and Cu 5 Zn 8 phases were formed, and no phase transformation was observed in the SZ/Alloy 25 couples. In the SZ/C194 couples, only Cu 5 Zn 8 phase formed at early stage of aging. The Sn tunneling phenomena promoted Cu-Sn IMC formed at a higher temperature and longer aging time. The Cu 6 Sn 5 phase was formed around the Sn-rich matrix and consumed the Cu atom from the C194 substrate. A diffusion-controlled mechanism was responsible for IMC growth in all couples. The activation energy for overall IMCs was 51.1 kJ/mol on SZ/C1990 HP, 45.7 kJ/mol on SZ/Alloy 25 couples, and 87.0 kJ/mol on SZ/C194.