Pitting and Dealloying of Solute-Rich Al-Cu-Mg-based Amorphous Alloys: Effect of Alloying with Minor Concentrations of Nickel

Abstract

The effect of Ni as a minor alloying element on the anodic dissolution behavior of solute rich Al-Cu-Mg-based amorphous alloys ((Al 75 Cu 17 Mg 8 ) 97 Ni 3 and Al 70 Cu 18 Mg 12 ) was studied. A small addition of Ni enhances both the pitting potential in 0.6 M NaCl, and resistance to dealloying 1 M HCl, and 5 M HCl þ 5 M LiCl solutions. A crystalline, Cu-rich nanoporous structure forms in pits as a result of selective dissolution of Al and Mg in both alloys, with the finest structure present in the Ni containing alloy. The increase in potential drop during pit stabilization due to the greater Ohmic resistance through the finer porous layer is one of the reasons that the pitting potential is ennobled. Ni in solid solution also hinders anodic dissolution in artificial pits which is speculatively linked to an increase the energy barrier for the dissolution of Al around Ni by forming stronger bonds. The Ni alloying also reduces the probability of finding Al-Al bonds. These result in a reduction in the dissolution kinetics which in turn ennobles the pit stabilization potential. Technological implications for corrosion resistant conventional Al-Cu-Mg alloy design and alternatively a new route to the creation of nanoporous Cu are discussed.

Tailored products of dealloying as-sintered Al–Cu alloys in sodium hydroxide solutions

“…Qin et al adopted Al-Cu-Hf amorphous alloys as precursors and mixed Cu/Cu 2 O/CuO were synthesized through dealloying in acid solutions. 20,21 Aburada et al 22 also produced hybrid Cu/Cu 2 O by dealloying an amorphous Al-Cu-Mg alloy in HCl solution. In addition, porous CuO nanoplates were also nally fabricated by dealloying an amorphous Al-Cu alloy lm and during that period a Cu 2 O intermediate was found.…”

Utilization of chemical stability diagrams for improved understanding of electrochemical systems: evolution of solution chemistry towards equilibrium

“…36 Alternatively, the authors proposed that the large volume fraction of Li-rich zones in the alloy results in preferential oxidation of Li compared to Mg. 36 The difference in Nernst potentials of Li and Mg may enable more oxidation of Li compared to Mg, as is commonly seen for alloys comprised of components with substantially different Nernst potentials. 6,13,[40][41][42] In the case of a congruently corroding binary alloy, the anodic charge was equally distributed between each element according to the composition ratio of the alloy. The procedure developed in Case Study I applicable to congruent dissolution of a corroding A-B alloy represented by a given…”

Anodic Dissolution Behavior of Al-Y Alloy in LiCl-KCl Eutectic and Its Passivation Inhibited Aided by LiF

“…Only some studies on the anodic dissolution of Al-based alloys in aqueous solution. 19,20 In addition, the passivation of aluminum was found in anodic dissolution of Al-containing alloy. Wang et al 21 explored the anodic dissolution of two typical γ-TiAl alloys in NaNO 3 solution by cyclic voltammetry and polarization technique.…”