Microstructural, mechanical, and electrical characterization of directionally solidified Al-Cu-Mg eutectic alloy

Abstract

The composition of an Al-Cu-Mg ternary eutectic alloy was chosen to be Al-30 wt% Cu-6 wt % Mg to have the Al2Cu and Al2CuMg solid phases within an aluminum matrix (alpha-Al) after its solidification from the melt. The alloy Al-30 wt % Cu-6 wt % Mg was directionally solidified at a constant temperature gradient (G = 8.55 K/mm) with different growth rates V, from 9.43 to 173.3 mu m/s, by using a Bridgman-type furnace. The lamellar eutectic spacings (lambda(E)) were measured from transverse sections of the samples. The functional dependencies of lamellar spacings lambda(E) ( lambda(Al2CuMg) and lambda(Al2Cu), in mu m), microhardness H-V (in kg/mm(2)), tensile strength sigma(T) (in MPa), and electrical resistivity rho (in Omega m) on the growth rate V (in mu m/s) were obtained as lambda(Al2CuMg)=3.05V(-0.31), lambda(Al2Cu)=6.35(-0.35),H-v = 308.3(V)(0.03) sigma(T)= 408.6(V)(0.14), and rho = 28.82 x 10(-8)(V)(0.11), respectively for the Al-Cu-Mg eutectic alloy. The bulk growth rates were determined as lambda(2)(Al2CuMg) V= 93.2 and lambda(2)(Al2Cu) V=195.76 mu m(3)/s by using the measured values of lambda(Al2CuMg), lambda(Al2Cu) and V. A comparison of present results was also made with the previous similar experimental results.