Effects of combined addition of Ca and Y on the corrosion behaviours of die-cast AZ91D magnesium alloy

•The combined addition of calcium and yttrium significantly improved the corrosion resistance of the die-cast AZ91D alloys.•The formation of the Al-Mn-Y phase instead of the Al-Mn-Fe phase significantly reduced the VPD values, which decreased micro-galvanic corrosion.•The stability of the surface film of the AZXW911 alloy were improved by the adding of a small amount of Y.