Interfacial Reactions Between Sn-Zn Alloys and Ni Substrates

Interfacial reactions between Sn-Zn alloys and Ni substrates after annealing at 463 K have been studied. Only one intermetallic compound (IMC), gamma-Ni5Zn21, was observed at the Sn-Zn/Ni interfaces, although other IMC(s) in the Ni-Sn and Ni-Zn system can stably exist at this temperature. Taking into account nucleation along with diffusion kinetics, formation of the reaction product has been reasonably modeled. In addition, growth kinetics for the reaction layer has been quantified. The results indicate that the growth rate of the gamma-Ni5Zn21 layer increases with Zn content, and that the layer growth obeys a parabolic law with annealing time, implying a diffusion-controlled mechanism.