Influence of yttrium addition on the corrosion behaviour of as-cast Mg–8Li–3Al–2Zn alloy

The influence of yttrium on the microstructure and corrosion behaviour of as-cast Mg–8Li–3Al–2Zn–xY alloys was investigated. The results show that Y addition leads to the formation of Al 2 Y particles and the transformation of α-Mg from the long needle-like to the round-like. The noble Al 2 Y particles on the grain boundary inhibit the galvanic corrosion between β-Li phase and α-Mg phase, and also weaken the corrosion occurrence inside β-Li phase due to the decrease of the AlLi phase. With Y addition, the corrosion resistance is improved gradually, especially when the content of Y is up to 1.5 wt-%. Moreover, Y addition makes the corrosion film become more compact, which can prevent the base materials from being attacked continuously.