Cast to wrought: A multidimensional analysis on microstructure, corrosion resistance, and electrochemical behaviour of WE43 magnesium alloy

his study explores the anisotropic behaviour and heat treatment influence the microstructure, mechanical and corrosion properties of WE43 magnesium alloy in both its as-cast and hot-rolled forms. The alloy’s phase structure and chemical composition were analyzed using X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). To investigate the anisotropic properties of rolled WE43 plate, it was sectioned along three orthogonal orientations: normal direction (ND), rolling direction (RD), and transverse direction (TD). These, along with the as-cast samples, underwent heat treatment at 450°C. Among all samples, the RD section exhibited higher hardness value (97 ± 3.8 HV) and a finer microstructure, with an average grain size of 8.67 ± 1.2 µm, significantly smaller than the as-cast alloy (25.6 ± 2.8 µm). Corrosion behaviour was examined through gravimetric techniques, electrochemical impedance measurements, and polarization studies in NaCl (3.5 %) solution. The RD sample showed lowest corrosion rate (0.05 mm/year), minimal weight loss (0.3 %), and a low corrosion current density (148.5 ± 8 μA cm²). It also displayed enhanced electrochemical stability, characterized by higher charge transfer resistance (12,700 Ω·cm²) and film resistance (15,000 Ω·cm²). Improved corrosion resistance was attributed to the formation of a protective surface layer consisting of Mg(OH)₂, ZrO₂, Gd₂O₃, Y₂O₃, and Nd₂O₃. Overall, heat treatment significantly improved the mechanical and corrosion performance of as-cast alloy, while its effect on the rolled alloy was relatively minor. With its refined microstructure and strong corrosion resistance, the rolled WE43 alloy stands out as a promising candidate for use in environments exposed to chlorides.

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