A magnesium based alloy containing at least 85.4 wt % Mg, 4.7 to 7.3 wt % aluminum, 0.17 to 0.60 wt % manganese, 0.0 to 0.8 wt % zinc, 1.8 to 3.2 wt % calcium, 0.3 to 2.2 wt % tin, and 0.0 to 0.5 wt % strontium. The alloy may comprising up to 0.004 wt % iron, up to 0.001 wt % nickel, up to 0.003 wt % copper, or up to 0.03 wt % silicon. In addition, the alloy may comprise up to 0.001 wt % beryllium.