| Abstract Scope |
Driven by lead-free regulations, the eco-friendly Sn-Zn solder is a promising alternative to traditional Sn-Pb. Accordingly, this study investigates the liquid/solid interfacial reactions, growth kinetics, and mechanical properties in the Sn-9Zn/Fe-xNi couples (x-10, 30, Alloy 42, 60 at.% Ni) reacted at 270°C for 1 to 10 h. Ni content in the Fe-xNi profoundly influences intermetallic compound (IMC) evolution. Growth kinetics reveal that low- and high-Ni systems are fully interface-reaction controlled (n≅1). Conversely, medium-Ni systems undergo a stepwise transition from early-stage grain boundary diffusion (n≅0.3) to late-stage interface-reaction control (n≅1), driven primarily by microstructural evolution. Furthermore, ball shear tests indicate brittle fractures across all joints. Alloy 42 achieves the highest shear strength (83.11 MPa) due to a dense and uniform IMC layer, while the low-Ni system yields the lowest (65.53 MPa) due to stress concentration. |