Microstructural, mechanical and electrical characterization of directionally solidified Al–Si–Mg eutectic alloy

Abstract

Al–12.95wt.% Si–4.96wt.% Mg alloy was directionally solidified upward at a constant temperature gradient (G=9.39K/mm) with different growth rates (V=8.64–165.20μm/s) by using a Bridgman type directional solidification furnace. The ternary eutectic alloy consists of irregular Si plates and Mg2Si Chinese’s script within an aluminum matrix. The dependencies of lamellar spacings (λSi and λMg2Si), microhardness, tensile strength and electrical resistivity on growth rates were obtained as HV=119.9 (V)0.07, σt=222.84 (V)0.20 and ρ=32.31×10−8 (V)0.13, respectively for Al–Si–Mg eutectic alloy. The bulk growth rates were determined as λSi2V=847.69 and λMg2Si2V=597.5μm3/s by using the measured values of λSi, λMg2Si and V. A comparison of present results was also made with the previous similar experimental results.