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The development of commercial magnesium die casting alloys has progressed over the past several decades. The most commonly used die casting alloy, AZ91D, with 9% aluminum content, has been and still is used in the majority of structural automotive applications. New magnesium alloys have been developed in the past several years to meet the needs of structural applications that require an appreciable amount of creep resistance and improved stress relaxation performance during service. Typical applications would include powertrain components. This paper provides further mechanical property data on the “AE-Type” magnesium alloys. These alloys consist primarily of aluminum and rare-earth additions to magnesium to increase creep resistance and stress relaxation performance attributes of the base metal. However, changes in tensile strength, elongation, etc. may also be realized.

The current strong interest in magnesium alloy die castings for automotive applications relies heavily on the “High Purity” concept. The basic knowledge of the detrimental effects of heavy element impurities on the general corrosion of magnesium alloys has been known for more than 60 years. However, it was not until the 1980's that the full potential of high purity alloys was recognized. The level of impurities (in particular, copper, nickel and iron) that can be tolerated in a die cast part exposed to a corrosive environment necessitates careful control throughout the complete manufacturing process, from ingot to finished product. In the present paper, some basic principles for the production of high purity alloys and the influence of subsequent melt handling practice in the die casting shop are discussed.