The effect of micro-alloying addition of Ca and Mn on castability and performance of Mg-based sacrificial anodes

Castability and electrochemical properties of the as-cast Mg-alloys, i.e., Mg-X wt% (X = 0.22 similar to 1.31) Ca alloy, Mg-X wt% (X=0.24 similar to 0.26) Mn-Y wt% (Y = 0.10 similar to 0.14) Ca alloys were evaluated. Out of these alloys, the Mg-0.26 wt% Mn-0.14 wt% Ca alloy shows the highest efficiency and lowest open-circuit potential. Flow length of the specimens decrease with an increase of Ca content. Serious decrease of flow ability in Mg melt is observed in Mg-1.31 wt% Ca alloy. However, flow length of Mg-Ca alloys is negligibly influenced by small amounts of Mn addition. The improved performance of Mg-Ca alloys, regardless of Mn addition is attributed to the homogeneous and refined microstructures, extremely electronegative potential of Ca. It is considered from that serious reduction in flow reduction of Mg-1.31 wt% Ca alloy is due to cast from large solidification interval.