Influence of Cr inclusion on the microstructural evolutions and tensile properties of Sn-5 wt% Sb solder alloy

The current study has been conducted to examine the impact of minor additions of Cr to Sn-5wt% Sb alloy. The novelty of this research work stems from this being the first study to correlate the tensile properties to the microstructure of high-temperature Sn-5wt% Sb solder alloy reinforced with different Cr contents. Sn-5Sb-xCr solders with Cr concentrations varying from 0 to 0.7 weight percent have been fabricated. The microstructural evolutions of the Sn-5Sb-xCr alloys have been examined using optical microscope field emission scanning electron microscope (FE-SEM) fitted with an energy dispersive X-ray spectroscope and X-ray diffraction (XRD) line profile analysis. The microstructure of binary alloy consists primarily of β-Sn matrix and SbSn intermetallic compounds. The SbSn intermetallic compounds, Sn-rich phase, and β-Sn matrix are shown to characterize the microstructure of Cr-containing alloys. The average grain size of β-Sn grains decreases from 69.53 to 21.19 µm with increasing the weight percentage of Cr from 0 to 0.7 wt%, respectively. The tensile experiments were carried out at several strain rates ( \(\dot{\varepsilon }\) $\dot{\epsilon }$ ) ranging from 1.02 × 10⁻⁴ to 1.96 × 10^–3 s⁻¹ in the deformation temperature range 298–373 K. The experimental results demonstrate that an increase in the strain rate ( \(\dot{\varepsilon }\) $\dot{\epsilon }$ ) increases the yield stress (σ_Y) and ultimate tensile stress (σ_UTS) of the studied materials, while an increase in the deformation temperature decreases them. The stress exponent values ranged from 3.07 to 12.68 for all tested solder alloys. All solders had an apparent activation energy (Q) that measured between 63.54 kJ mol⁻¹ and 77.34 kJ mol⁻¹, which is comparable to the dislocation climb mechanism.