Tailoring Microstructural and Electrical Properties of Hypoeutectic Sn-Cu Through Ni Doping

The present study aims to understand the effect of Ni (0.05 and 0.1wt.%) on the microstructural variations and electrical resistivity of Sn-0.7wt.%Cu-xNi alloys by weight, considering the following study conditions: (i) high cooling rates with refined microstructure and (ii) low cooling rates with thicker microstructures, metal/mold interface of 5 mm and 90 mm, respectively. Structural characterization was carried out using x-ray diffraction and scanning electron microscopy to support the electrical report. The four-point probe method was used to determine the electrical resistivity of the studied alloys. The structural analyses confirmed fibrous-type Cu₆Sn₅ and (Cu,Ni)₆Sn₅ intermetallics. Lower values of electrical resistivity were associated with higher fractions of the β-Sn phase, regardless of the growth morphology of the solid-liquid interface. A decrease in the electrical resistivity was observed with the addition of Ni on the Sn-Cu-Ni alloys, a consequence of the refined microstructures, i.e., those having a higher Sn phase fraction.