Synergetic role of Ni and GOns to improve the microstructure and mechanical creep rate of Sn-5.0Sb-0.7Cu solder alloy

Abstract

Abstract The role of minor additions of Ni and GOns to Sn- 5 wt% Sb- 0.7 wt% Cu (SSC-507) has been explored. Findings of scanning electron microscopy (SEM), energy dispersive x-ray spectrometry (EDX), and x-ray diffractometry (XRD) display the new phases like (Cu,Ni)6Sn5 and the size decrement of β-Sn grains. A slight increase in the melting temperature was observed using differential scanning calorimetry (DSC) analysis due to adding Ni (ΔTm = 1.02 °C) and GOns (ΔTm = 0.75 °C). Interestingly, 0.1 wt% Ni addition reduced the under-cooling by ∼28%, whenever adding of 0.1 wt% GOns enhanced the under-cooling by ∼115%. The average size of β-Sn grains of SSC-507 plain solder was decreased from ∼150 to ∼70 μm due to adding of Ni and then GOns. The enhanced creep resistance of SSC-Ni-GOns alloy motivated the values of creep fracture and enhanced the stress exponent parameters (n) by ∼27%. The outcomes of tensile creep examination demonstrate that increasing levels of stress and testing temperatures raise the steady-state creep rates for all tested alloys. The average activation energy (E) for the three solders ranged from ∼46.5 kJ mol−1 to ∼54.3 kJ mol−1 which close to that of pipe-diffusion mechanism in Sn based solder alloy.