Sn–3.0Ag–0.5Cu nanocomposite solders reinforced by graphene nanosheets

Various weight percentages (0, 0.02, 0.04, 0.06, 0.08, and 0.1 wt%) of graphene nanosheets (GNSs) were incorporated to Sn–3.0Ag–0.5Cu (SAC) solder using the powder metallurgy route. The physical, thermomechanical, wetting, microstructural and mechanical properties were evaluated. Experimental results present that the density and the coefficient of thermal expansion of nanocomposite solders are lower than those of plain SAC solder, while the wettability of nanocomposite solders is improved with the increasing addition of GNSs. Besides, as expected, adding GNSs has slight influence on melting temperature of SAC solder, as the melting temperature of an alloy is its inherent physical property. Furthermore, because the load can be transferred from matrix to GNSs, as well as microstructural refinement (the size of β-Sn decreases and the area fraction of eutectic network increases) and an increase in dislocation density after adding GNSs, the microhardness and shear strength are also improved with the elevating weight percentages of GNSs.