Improvement of mechanical properties of Sn–58Bi alloy with multi-walled carbon nanotubes

Carbon nanotubes (CNTs) reinforced Sn–58Bi composites were successfully fabricated through ball-milling method and low temperature melting process. The influence of multi-walled carbon nanotubes (MWCNTs) on the mechanical strength and ductility of Sn–58Bi lead-free alloy was studied. The mechanical test results show that the bending strength of Sn–58Bi–0.03CNTs (mass fraction, %) composite is increased by 10.5% than that of the Sn–58Bi alloy, which can be attributed to the reduction of Sn-rich segregation and the grain refinement. The toughness of Sn–58Bi–0.03CNTs composite is increased by 48.9% than that of the matrix materials. It is indicated that the influence of CNTs on the strength of Sn–58Bi–xCNTs composite is insignificant. In addition, the fracture mechanism of CNTs reinforced Sn–Bi composite was analyzed. The corresponding fracture surface comparison between the Sn–58Bi–0.03CNTs composite and the monolithic Sn–58Bi alloy was made to identify the influence of CNTs on the fracture behavior and the reinforcing effect of CNTs.