High Purity Magnesium Die Casting Alloys: From Ingot to Cast Product
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.