Effect of Temperature Gradient and Growth Velocity on Microstructure and Mechanical Properties on Zn–7Al–3Cu Ternary Eutectic Alloy

Abstract

In the present work, microstructure and mechanical properties of Zn–7Al–3Cu (wt%) ternary alloy are investigated depending on the temperature gradient and growth velocity. The alloy was prepared in the designated composition in a vacuum melting and casting furnace and then filled into the graphite sample moulds. The samples were directional solidified with various temperature gradients (6.7–10.7 K/mm) at a constant growth velocity (16.4 μm/s) and with various growth velocities (8.3–166.0 μm/s) at a constant temperature gradient (10.7 K/mm) in a Bridgman-type furnace. Microstructural images of solidified samples were taken with light microscope and scanning electron microscope. Eutectic spacings were measured from these images. Microhardness, ultimate tensile strength, yield strength and modulus elasticity values of each sample produced at various solidification parameters were also measured. The effect of temperature gradient and growth velocity on the eutectic spacing, microhardness, ultimate tensile strength, yield strength and modulus elasticity was determined using linear regression analysis. While the microhardness, ultimate tensile strength, yield strength and modulus elasticity values increased with increasing temperature gradient and growth velocity values or decreasing eutectic spacing, the elongation values decreased. Fractographic results show that the type of fracture is brittle.