Magnesium is a shiny gray metal that is the lightest structural metal. With a density of 1.738 grams per cubic centimeter, magnesium is lighter than aluminum and about two-thirds the weight of steel or nickel. Magnesium has remarkable physical properties that make it ideal for applications where weight reduction is critical. It has a hexagonal-close-packed crystalline structure that gives it good creep resistance at elevated temperatures as well as excellent castability. Magnesium also has high specific strength, meaning it can withstand high stresses considering its low density.

Magnesium metal has a melting point of 649°C and a boiling point of 1,090°C. It is ductile and can be readily machined, cast, rolled or drawn into wires. However, magnesium is highly flammable and reactive, readily igniting in air at temperatures over 360°C. It must therefore be protected from moisture and oxidizing environments during storage, handling, and processing to prevent corrosion. Finished magnesium components also require protective coatings or alloying to prevent ignition.

Major Alloying Elements and Their Effects

To enhance the mechanical and corrosion resistance properties of Magnesium Metal, it is usually alloyed with other metals. Aluminum is the most common alloying element for magnesium. Adding 4-12% aluminum to magnesium improves its strength, hardness, and corrosion resistance without significantly increasing its density. Aluminum-magnesium alloys are widely used for aircraft applications due to their high specific strength.

Zinc is another important alloying element for magnesium. Adding 1-5% zinc increases the strength and hardness of magnesium more than aluminum alone. Magnesium-zinc alloys have better casting properties than pure magnesium or magnesium-aluminum alloys. Common magnesium-zinc alloys include ZK60, which contains 5-6% zinc and is used for die casting auto parts.

Manganese is added in small amounts, around 0.2-1%, primarily to enhance the creep resistance of magnesium alloys at elevated temperatures. Rare earth elements such as neodymium and mischmetal (a cerium-containing alloy) are also sometimes added in minute quantities to refine magnesium grain structure for improved strength and plasticity.