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.