Determination of mechanical, electrical and thermal properties of the Sn―Bi―Zn ternary alloy

• Published in: Journal of non-crystalline solids 2011-07, Vol.357 (15), p.2876-2881
• Main Authors: Çadırlı, Emin, Böyük, Uğur, Kaya, Hasan, Maraşlı, Necmettin
• Format: Article
• Language: English
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Directional solidification; Elasticity. Plasticity; Electrical resistivity; Enthalpy; Eutectic alloys; Eutectic temperature; Exact sciences and technology; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microhardness; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Solders; Solidification; Temperature gradient; Tensile stress; Thermal properties; Tin base alloys; Zinc base alloys
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2011.03.025

The development of lead-free solders has emerged as one of the key issues in the electronics packaging industries. Sn―Zn―Bi eutectic alloy has been considered as one of the lead-free solder materials that can replace the toxic Pb―Sn eutectic solder without increasing soldering temperature. This study investigates the effect of temperature gradient and growth rate on the mechanical, electrical and thermal properties of the Sn―Zn―Bi eutectic alloy. Sn-23wt.% Bi-5wt.% Zn alloy was directionally solidified upward with different growth rates (V=8.3–478.6μm/s) at a constant temperature gradient (G=3.99K/mm) and with different temperature gradients (G=1.78–3.99K/mm) at a constant growth rate (V=8.3μm/s) in the Bridgman-type growth apparatus. The microhardness (HV), tensile stress (σt) and compressive stress (σc) were measured from directionally solidified samples. The dependency of the HV, σt and σc for directionally solidified Sn-23wt.% Bi-5wt.% Zn alloy on the solidification parameters (G, V) were investigated and the relationships between them were obtained by using regression analysis. According to present results, HV, σt and σc of directionally solidified Sn-23wt.% Bi-5wt.% Zn alloy increase with increasing G and V. Variations of electrical resistivity (ρ) for cast samples with the temperature in the range of 300–420K were also measured by using a standard dc four-point probe technique. The enthalpy of fusion (ΔH) and specific heat (Cp) for same alloy was also determined by means of differential scanning calorimeter (DSC) from heating trace during the transformation from eutectic liquid to eutectic solid. ► The relationships among HV , V and G can be given as,HV=kG0.16andHV=kV0.06 ► The values of the tensile and compressive stresses increase with increasing the values of G and V. ► The resistivity increased from 22.1×10−8 to 30.0×10−8Ω m by increasing temperature.