Investigation of interfacial reactions in the Sn/Fe-xNi couple

The solid/liquid interfacial reactions between Sn and several Fe-Ni alloys at 270°C were investigated. The results indicated that when the Ni content was less than 40.7 at.% in the Fe-Ni alloys, only the the FeSn₂ phase with needle shape was formed at the interface. If the content of Ni in substrates is 60 at.%, the bulk shape of the FeSn₂ phase was formed at the interface. When the content of Ni in substrates is 80 at.%, the FeSn₂ phase was formed first, and then it was transferred to FeSn₂ and Ni₃Sn₄ phases as the reflowing time was longer than 4 h. If the Ni content in Fe-Ni alloy was 90 at.%, both FeSn₂ and Ni₃Sn₄ phases were formed; when the aging time was increased to 4 h, only the Ni₃Sn₄ phase was observed at the interface. The Ni₃Sn₄ phase was formed in the Sn/Ni couple.