Magnesium / Magnesium Alloy (UNS M) Nonferrous Metals and Alloys

Description

Magnesium and magnesium alloys are non-ferrous metals known for their low density and relatively high strength-to-weight ratio. These materials are characterized by good ductility, moderate strength, and good corrosion resistance. They are commonly alloyed with elements such as aluminum and zinc to enhance their properties.

Working Principle

Magnesium alloys work by leveraging their hexagonal close-packed structure, which requires them to be formed at elevated temperatures. This structure contributes to their lightweight nature, making them useful in applications where weight reduction is critical. The alloys can be precisely engineered to control corrosion rates, which is particularly useful in applications like deep-sea equipment where controlled corrosion is necessary. Additionally, magnesium alloys can be enhanced for hydrogen storage by alloying with certain metals and intermetallic compounds, which improve their hydrogenation capabilities.

Applications

Magnesium and magnesium alloys are used in a variety of industries due to their lightweight and corrosion-resistant properties. They are prevalent in the aerospace industry for structural components. In the automotive industry, they are used in applications such as motor racing due to their lightweight nature. Other applications include electronics, nuclear industry components, flash photography, flares, sporting goods, and tools. Specific examples include their use in helicopter gearboxes due to their excellent damping capacity and in the crankcase of Volkswagen's air-cooled Beetle engine.

Advantages over other Nonferrous Metals and Alloys

Compared to high-strength aluminum alloys, magnesium alloys are significantly lighter, which makes them competitive on a specific strength and modulus basis. They also have excellent damping characteristics, making them suitable for high-vibration environments. Despite being more expensive than aluminum, the ease of manufacturing magnesium components often mitigates the cost difference.

Limitations

Magnesium alloys have several limitations, including lower tensile strength and modulus of elasticity compared to aluminum alloys. They also have poor corrosion resistance, occupying the highest anodic position on the galvanic series, which makes them susceptible to corrosion. Additionally, magnesium alloys have reduced strength at high temperatures, which can limit their use in certain applications.

Considerations

When considering magnesium alloys, it is important to account for their initial costs, which are generally higher than those of aluminum alloys. However, the manufacturing process for magnesium components is relatively easy, which can offset some of the initial costs. Durability is a concern due to their poor corrosion resistance, which may lead to higher maintenance and replacement costs. The alloys' susceptibility to corrosion also necessitates careful consideration of operating environments to ensure longevity and performance.