Horizontally Solidified Al–3 wt%Cu–(0.5 wt%Mg) Alloys: Tailoring Thermal Parameters,Microstructure, Microhardness,and Corrosion Behavior

In the present experimental investigation, Al–3 wt%Cu and Al–3 wt%Cu–0.5 wt%Mg alloys castings are produced by a horizontal solidification technique with a view to examining the interrelationship among growth rate(G_R), cooling rate(C_R), secondary dendrite arm spacing(λ_2), Vickers microhardness(HV), and corrosion behavior in a 0.5 M NaCl solution.The intermetallic phases of the as-solidified microstructures, that is, h-Al_2Cu, S–Al_2CuMg, and x-Al_7Cu_2 Fe, are subjected to a comprehensive characterization by using calculations provided by computational thermodynamics software, optical microscopy, and scanning electron microscopy/energy-dispersive spectroscopy. Moreover, electrochemical impedance spectroscopy and potentiodynamic polarization tests have been applied to analyze the corrosion performance of samples of both alloys castings. Hall–Petch-type equations are proposed to represent the HV dependence on λ_2. It is shown that the addition of Mg to the Al–Cu alloy has led to a considerable increase in HV; however, the Al–Cu binary alloy is shown to have lower corrosion current density(i_(corr)) as well as higher polarization resistance as compared to the corresponding results of the Al–Cu–Mg ternary alloy.

Horizontally Solidified Al-3 wt%Cu-(0.5 wt%Mg) Alloys: Tailoring Thermal Parameters,Microstructure, Microhardness,and Corrosion Behavior

In the present experimental investigation, Al-3 wt%Cu and Al-3 wt%Cu-0.5 wt%Mg alloys castings are produced by a horizontal solidification technique with a view to examining the interrelationship among growth rate (G_R), cooling rate (C_R), secondary dendrite arm spacing (λ₂), Vickers microhardness (HV), and corrosion behavior in a 0.5 M NaCl solution. The intermetallic phases of the as-solidified microstructures, that is, θ-Al₂Cu, S-Al₂CuMg, and ω-Al₇Cu₂Fe, are subjected to a comprehensive characterization by using calculations provided by computational thermodynamics software, optical microscopy, and scanning electron microscopy/energy-dispersive spectroscopy. Moreover, electrochemical impedance spectroscopy and potentiodynamic polarization tests have been applied to analyze the corrosion performance of samples of both alloys castings. Hall-Petch-type equations are proposed to represent the HV dependence on λ₂. It is shown that the addition of Mg to the Al-Cu alloy has led to a considerable increase in HV; however, the Al-Cu binary alloy is shown to have lower corrosion current density (i_corr) as well as higher polarization resistance as compared to the corresponding results of the Al-Cu-Mg ternary alloy.