Abstract: A method of improving the corrosion resistance of magnesium alloy castings containing more than about 2 per cent by weight of aluminum is described. The method comprises: first selecting a casting process suitable for developing at least on the surface of the casting a microstructure comprising aluminum-depleted magnesium grains surrounded by an aluminum-rich layer and preferably incorporating at least some of an intermetallic compound based on the composition Mg17Al12; and second, heat treating at least the outer layer of the casting to promote additional intermetallic compound precipitation as required.

Abstract: The surface of a magnesium or magnesium alloy part is protected from corrosion by a coating of adherent, electrically conductive material that is electrolytically anodic to the magnesium-containing substrate. For example, the magnesium alloy has a microstructure with portions that are anodic and cathodic to each other, but the coating contains species (e.g., lithiated graphite particles in a polymeric binder) that are anodic to all phases in the magnesium alloy microstructure so that when the coating is damaged and the part surface is exposed, the coating is sacrificially consumed by electrochemical corrosion and the part is spared.

Abstract: Die casting of some magnesium alloys may yield castings that are susceptible to corrosion when exposed to salt water or other aggressive oxidizing environments. Such corrosion may result from the existence of different microstructures in a cross-section of the die casting (e.g. between the surface of the part and the center) that produce galvanic couples that are susceptible to such corrosive attack. However, a die temperature may be determined for casting of the part such that a more uniform cross-sectional microstructure is produced in which minimal or negligible galvanic potentials are produced.

Abstract: The surface of a magnesium or magnesium alloy part is protected from corrosion by a coating of adherent, electrically conductive material that is electrolytically anodic to the magnesium-containing substrate. For example, the magnesium alloy has a microstructure with portions that are anodic and cathodic to each other, but the coating contains species (e.g., lithiated graphite particles in a polymeric binder) that are anodic to all phases in the magnesium alloy microstructure so that when the coating is damaged and the part surface is exposed, the coating is sacrificially consumed by electrochemical corrosion and the part is spared.