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. (c) 2007 Elsevier B.V. All rights reserved.