Interfacial Reactions in Sn/Fe-xNi Couples

The interfacial reactions between Sn and several Fe-xNi alloys were investigated in this study. Two different FeSn₂ phase types formed at the Sn/Fe-40.8 at.%Ni (Sn/alloy 42) interface. When the Ni content of the Fe-Ni alloy was less than 80 at.%, only the FeSn₂ phase with layer structure could be formed at the interface. When the Ni content was increased to 80 at.% to 90 at.%, both FeSn₂ and Ni₃Sn₄ phases formed in the Sn/Fe-xNi couples. When the Ni content was larger than 95 at.%, only the Ni₃Sn₄ phase was formed at the interface. A fast reaction rate and the thickest intermetallic compound (IMC) layer could be observed in the Sn/Fe-90 at.%Ni couple. The reaction paths of each reaction couple at 270°C were as follows: L/FeSn₂/Fe-40.8 at.%Ni (alloy 42), L/FeSn₂/Ni₃Sn₄/Fe-80 at.% Ni, and L/Ni₃Sn₄/Fe-95 at.%Ni, respectively.