Comparative study of MgTi and AlV alloys: Corrosion kinetics,impedance response and surface degradation in H 2 SO 4 and NaCl solutions

Abstract

This study comparatively evaluates the corrosion behaviour of binary magnesium–titanium (MgTi) and aluminium–vanadium (AlV) alloys recovered from automotive scrap in dilute H₂SO₄ (0.000625–0.1 M), NaCl (0.5–4.5 wt%) and mixed H₂SO₄/NaCl environments. Corrosion performance was assessed using gravimetric weight-loss, potentiodynamic and cyclic polarisation, open-circuit potential monitoring, electrochemical impedance spectroscopy (EIS) and post-exposure optical microscopy. AlV alloy exhibited markedly superior corrosion resistance in all tested media, forming a compact, self-healing oxide film that conferred high polarisation resistance and partial passivation capability. In contrast, MgTi alloy underwent rapid active dissolution, displaying very high corrosion rates, low impedance, unstable open-circuit potentials and severe surface degradation dominated by pitting and general attack. The presence of vanadium in the aluminium matrix was responsible for the stable passive layer, whereas the MgTi system formed only porous and non-protective corrosion products. The results demonstrate that, among the two lightweight binary alloys examined, AlV possesses significantly greater resistance to acidic, chloride-containing and mixed corrosive environments, making it considerably more suitable for structural applications where exposure to de-icing salts, acidic condensation or marine atmospheres is anticipated. MgTi, however, requires additional protective measures (coatings, inhibitors or further alloying) for practical use in aggressive service conditions.