Electrochemical Characterization of a Novel Mg70Al18Zn6Ca4Y2 Low Entropy Alloy in Different Aqueous Environments

In the present investigation, design and development of a novel Mg-based multicomponent low entropy alloy (Mg LEA-Mg₇₀Al₁₈Zn₆Ca₄Y₂) was carried out using Disintegrated Melt Deposition (DMD) technique. Various electrochemical techniques such as potentiodynamic polarization test (PDP) and electrochemical impedance spectroscopy (EIS) are used to investigate the electrochemical behaviour of the present Mg-LEA alloy at different molar concentrations in acidic (HCl), neutral (NaCl) and alkaline (NaOH, at different pH levels) solutions. The results show that, this alloy easily gets corroded with the increase of Cl⁻ ion concentration due to the breakdown of the Mg(OH)₂ passive layer in both acidic and neutral solutions. However, in the case of alkaline solution, the corrosion resistance of the alloy increases due to the formation of a stable Mg(OH)₂ layer along with AlMg₂Zn and Al₂Y phases, which is more stable than αMg. The ranking of Mg-LEA alloy’s corrosion rate is as HCl> NaCl> NaOH. The impedance measurements have correlated well with polarizations results and the data obtained according to the equivalent circuit provide insights between electrode and electrolyte interface. Through SEM analysis, pitting corrosion was observed in Mg-LEA alloy in acidic and neutral solutions and their chemical compositions were obtained using energy-dispersive X-ray spectroscopy (EDS).