Corrosion Behavior of Diecast Mg–Al–Mn–Ca–Si Magnesium Alloy

Abstract

The corrosion behavior of diecast Mg–Al–Mn–Ca–Si (AMXS6020) magnesium alloy with superior flame-retardance and heat-resistance was systematically investigated and compared to diecast AZ91D magnesium alloy and ADC12 aluminum alloy by salt spray test, cyclic corrosion test, electrochemical experiment, scanning electron microscopy and energy dispersive X-ray spectroscopy. The results showed that AMXS6020 alloy had a higher corrosion resistance than AZ91D and ADC12 alloys. The superior corrosion resistance of AMXS6020 alloy was attributed to netlike eutectic structure consisting of (Al, Mg)₂Ca and α-Mg, which could hinder the corrosion growth. The barrier effect of netlike (Al, Mg)₂Ca phase structure on corrosion growth was also confirmed by potentiodynamic polarization.

Fig. 5 Pictures of as-diecast specimens of Mg and Al alloys before and after SST for 96 hours.