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 (α-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 μm/s, by using a Bridgman-type furnace. The lamellar eutectic spacings (λ_E) were measured from transverse sections of the samples. The functional dependencies of lamellar spacings λ_E (${\lambda _{A{l_2}CuMg}}$ and ${\lambda _{A{l_2}Cu}}$ in μm), microhardness H _V (in kg/mm²), tensile strength σ_T (in MPa), and electrical resistivity ρ (in Ω m) on the growth rate V (in μm/s) were obtained as ${\lambda _{A{l_2}CuMg}} = 3.05{V^{ - 0.31}}$, ${\lambda _{A{l_2}Cu}} = 6.35{V^{ - 0.35}}$, ${H_V} = 308.3{\left( V \right)^{ - 0.33}}$; σ_T= 408.6(V)^0.14, and ρ = 28.82 × 10^–8(V)^0.11, respectively for the Al–Cu–Mg eutectic alloy. The bulk growth rates were determined as $\lambda _{A{l_2}CuMg}^2V = 93.2$ and $\lambda _{A{l_2}Cu}^2V = 195.76$ by using the measured values of ${\lambda _{A{l_2}CuMg}}$, ${\lambda _{A{l_2}Cu}}$ and V. A comparison of present results was also made with the previous similar experimental results.