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

Abstract

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 (k 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 2 Cu, S-Al 2 CuMg, and x-Al 7 Cu 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 k 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.

Microstructure of a Ti–50 wt% Ta alloy produced via laser powder bed fusion

“…4c. For conditions of growth where the ratio of G L ∕V is much smaller than the ratio of ΔT 0 ∕D L , the interface becomes columnar dendritic in shape [33,34], as shown in Fig. 4b.…”

Microstructure Growth Morphologies, Macrosegregation, and Microhardness in Bi–Sb Thermal Interface Alloys

“…The temperature-time data, which were recorded at a frequency of 5 Hz and stored in a Lynx datalogger, were used to calculate both the solidification cooling rate (Ṫ) and the growth rate (V L ) through well-known experimental techniques. [39][40][41] The resulting castings were sectioned along their vertical axis, grounded, and etched with a solution of aqua regia reagent (3HCl:1HNO 3 ) to reveal the corresponding macrostructure. Furthermore, metallographic specimens were extracted from different sections along the length of the castings to investigate the microstructure evolution from the cooled base to the top of the casting.…”

“…When the thermocouple closest to the chilled base measured a temperature of 10% above the alloy liquidus temperature, the electrical windings were disconnected, and the water flow was immediately initiated, thus permitting the onset of the directional solidification. The temperature–time data, which were recorded at a frequency of 5 Hz and stored in a Lynx datalogger, were used to calculate both the solidification cooling rate () and the growth rate ( V L ) through well‐known experimental techniques …”

Length scale of solidification microstructure tailoring corrosion resistance and microhardness in T6 heat treatment of an Al–Cu–Mg alloy

“…The experiments carried out with the investigated Al-Cu-Mg alloy, involving the preparation, thermal data during solidification, as well as macrostructural and microstructural characterisations are detailed in previous papers [12,14]. Table 1 shows of commercially pure Al and Cu as well as the Mg-7wt-%Al master alloy, which were used to prepare the investigated alloy are reported in Table 1.…”