Abstract
In this study, the strength-ductility trade-off and stress relaxation (SR) behavior of Sn–5Sb-0.3Cu (SSC503) alloy reinforced with (0, 0.05and 0.1 wt%) multi-walled carbon nanotubes (MWCNT) have been investigated under different pre-strains and initial stress levels. The results show that the pre-deformation can extend the duration of initial SR stage and significantly promote the stress reduction rate. The SSC503–0.05MWCNT composite alloy exhibits the optimum increase in SR resistance, yield strength (σy), ductility, and creep threshold stresses with the values of 75.8%, 17.3%, 77.9% and 10.6%, respectively. The scanning transmission electron microscopy (STEM) images and electron probe microanalyzer (EPMA) revealed that the distribution of MWCNT in SSC503 alloy was concentration dependent. 0.05MWCNT concentration induced a dendritic/cellular transition of β-Sn grains and restrained the growth of β-Sn, Cu6Sn5, SnSb, Sn3Sb2 and Cu2Sb IMC compositions, whereas 0.1MWCNT led to the partial agglomeration of MWCNT into β-Sn grain surfaces. MWCNTs are adsorbed at the surface-active atoms of Sb metalloid to form Sb-coated MWCNTs (Sb/C) in situ, which act as a bridge between MWCNT and Cu6Sn5 particles. The modified composites represent a vital technological progress for utilization in high temperature solder applications.
The effects of MWCNTs on the stress relaxation resistance and evading the strength-ductility trade-off in Sn–5Sb-0.3Cu solder alloy have been studied. Sb atoms enhanced the formation of Sb/C particles, which act as a bridge between MWCNT and Cu6Sn5 particles. The modified composites with 0.05MWCNT concentration increased the SR resistance, yield strength (σy), ductility, and creep threshold stresses to the optimum values. [Display omitted]
•The effects of MWCNTs on the mechanical properties of SSC503 alloys were studied.•Sb atoms enhance the formation of Sb-coated MWCNTs (Sb/C).•The Sb/C act as a bridge between MWCNTs and Cu6Sn5 particles as well as β-Sn matrix.•The distribution of MWCNT in SSC503 alloy was concentration dependent.•The optimum increase in SR resistance, σy, UTS, El% was found in SSC503–0.05MWCNT.