Effect of Nb nanoparticles on microstructure and mechanical properties of Sn58Bi/Cu joint

Objective The aim was to investigate effect of content of Nb nanoparticles on microstructure and properties of Sn58Bi/Cu joints during aging process and improve microstructure and properties of SN58Bi/Cu joints. Methods SEM, EDS and XRD were used to observe effect of content of Nb nanoparticles on microstructure of Sn58Bi/Cu joints. Universal testing machine was used to analyze effect of Nb nanoparticles on shear strength of Sn58Bi/Cu joints. Results The results showed that Nb₃Sn nano-compounds were generated in the weld of Sn58Bi-Nb/Cu after the addition of Nb nanoparticles, which could slow down microstructure coarsening of the weld, reduce growth rate of interfacial intermetallic compound (IMC) layer, inhibit Bi phase segregation, reduce interfacial pores and cracks, and improve service performance of the joints during aging process. At the aging temperature of 120 ℃, when the addition (wt.%) of Nb nanoparticles was 0.9%, IMC layer growth rate of Sn58Bi-0.9Nb/Cu joints was 0.13 μm²/h, which was 45% lower than that of Sn58Bi/Cu joint under the same aging conditions. After aging for 15 d, shear strength of Sn58Bi-0.9Nb/Cu joints was 9.3 MPa, which was 84% higher than that of Sn58Bi/Cu joint under the same aging conditions. Conclusion According to the research, Sn58Bi-0.9Nb/Cu joints had higher shear strength.