Effect of Nd on the corrosion behaviour of AM50 and AZ91D magnesium alloys in 3.5wt.% NaCl solution

► Nd addition modified the microstructure of AM50 and AZ91D magnesium alloys. ► Volume of β-Mg17Al12 phase was reduced and Al2Nd/Al–Mn–Nd particles were formed. ► Nd-containing intermetallics revealed lower potential than Al–Mn inclusions. ► 0.7–0.8wt.% Nd reduced the corrosion rate of AM50 and AZ91D alloys by 90%. The corrosion performance of AM50 and AZ91D alloys containing up to 1.5wt.% Nd was investigated by electrochemical and gravimetric measurements in 3.5wt.% NaCl at 22°C. The alloys were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and surface potential maps. In Nd-containing alloys, formation of Al2Nd and Al–Mn–Nd intermetallic compounds reduced the volume fraction and modified the morphology of the β-Mg17Al12 phase. The addition of Nd improved the corrosion resistance of the alloys due to increased passivity of the surface film and suppression of micro-galvanic couples.