Influence of single-wall carbon nanotube addition on the microstructural and tensile properties of Sn–Pb solder alloy

Single-wall carbon nanotubes (SWCNTs) functionalized 63Sn–37Pb solders was synthesized. Composite solders up to 1 wt.% reinforcement of SWCNTs were prepared. The composite specimens were characterized by X-ray diffraction (XRD), Field-emission scanning electron microscope (FE-SEM). Melting characteristics of the SWCNT based solders were determined by differential scanning calorimetry. Microstructures of the composite solders were examined by FE-SEM at higher magnification for the observation of the CNT distribution. Mechanical properties of the composite specimens were compared with those of the pure 63Sn–37Pb solder specimens and found that the ultimate tensile strength increased by 30% with the 0.3 wt.% addition of CNTs. Hardness values of the CNT based composites have shown higher Vickers hardness compared to un-reinforced counterparts. The enhanced mechanical properties are resulting from the possible load-transfer mechanisms of the CNTs, which is discussed in detail. The fractrographic examination conducted by FE-SEM indicated the existence of ductile features in the form of dimples in all the composite solders with different weight proportions; it is evident from the micrographs that much reduced ductility is observed in the specimens reinforced with the higher wt.% of CNTs.