Characterization of a Directionally Solidified Sn–Pb–Sb Ternary Eutectic Alloy

A Sn–40.5wt%Pb–2.6wt%Sb ternary eutectic alloy was prepared using a vacuum melting furnace and a casting furnace. The samples were directionally solidified at a constant growth rate (V = 16.5 μm/s) under different temperature gradients (G = 1.05–3.88 K/mm) and at a constant temperature gradient (G = 3.88 K/mm) under different growth rates (V = 8.3–498 μm/s). The effects of G and V on lamellar spacing (λ), microhardness (HV), and ultimate tensile strength (σ) were determined. The lamellar spacing and microhardness were measured from both longitudinal and transverse sections of the sample. The relationships between solidification parameters (G, V), microstructure parameters (λ _L, λ _T), and mechanical properties (HV, σ) were determined from linear regression analysis. It was found that the microhardness and tensile strength increase with increasing G and V as well as with decreasing λ.