Dependence of microstructure, microhardness, tensile strength and electrical resistivity on growth rates for directionally solidified Zn-Al-Sb eutectic alloy

Abstract

Zn-5.3 wt.% Al-0.8 wt.% Sb alloy was directionally solidified upward at a constant temperature gradient (G = 2.39 K mm(-1)) with a wide range of growth rates (V) (9.70-2013.40 mu m s(-1)) by using a Bridgman type directional solidification furnace. The average values of eutectic spacing (lambda), microhardness (HVT), ultimate tensile strength (sigma(UTS)) and electrical resistivity (rho) were measured from transverse sections of the directionally solidified samples. The dependency of lambda, HVT, sigma(UTS) and rho on V were experimentally obtained by using linear regression analysis for low, high and all growth rates. The bulk growth rates were also determined by using the measured values of lambda and V for low, high and all growth rates. The results obtained in the present work were compared with the Jackson-Hunt eutectic theory and similar experimental results in the literature. Also, the specific heat difference (Delta C-P) and enthalpy of fusion (Delta H) for the Zn-Al-Sb alloy were determined by means of differential scanning calorimetry.