Magnesium (Mg)
Magnesium is the lightest structural metal, with a density of just 1,738 kg/m³ — 35% lighter than aluminum and 77% lighter than steel. Its exceptional strength-to-weight ratio drives growing adoption in automotive, aerospace, and electronics, though its reactivity requires careful handling during processing.
Properties
- Density
- 1,738 kg/m³
- Melting Point
- 650 °C
- Boiling Point
- 1,091 °C
- Thermal Conductivity
- 156 W/(m·K)
- Electrical Resistivity
- 4.39 × 10⁻⁸ Ω·m
- Tensile Strength
- 160–365 MPa
- Yield Strength
- 90–280 MPa
- Hardness
- 30–90 HB
- Elongation
- 2–21%
- Crystal Structure
- HCP
Common Grades
- AZ91D: Most common die casting alloy (9% Al, 1% Zn). Automotive housings, electronics, power tools.
- AZ31B: Wrought alloy for sheet and extrusions. Laptop cases, vibration test fixtures, tooling plates.
- AM60B: High-ductility die casting alloy. Automotive steering wheels, seat frames, instrument panels.
- WE43: High-performance rare-earth alloy. Aerospace, military, bioabsorbable medical implants.
Applications
- Automotive: Transmission cases, steering columns, instrument panels, wheel rims, engine blocks
- Aerospace: Helicopter gearboxes, satellite structures, missile components, thrust reversers
- Electronics: Laptop/tablet housings, camera bodies, mobile phone frames, HDD components
- Medical: Bioabsorbable implants, stents, bone screws (dissolve in body over time)
- Industrial: Sacrificial anodes, desulfurization of steel, Grignard reagent chemistry
FAQ
Is magnesium flammable?
Solid magnesium components are difficult to ignite (ignition ~473°C for bulk material). However, fine chips, powder, and thin shavings ignite easily and burn at 3,100°C with an intensely bright white flame. Class D fire extinguishers (dry powder) are mandatory. Never use water — it reacts violently with burning magnesium.
Why is magnesium used for laptop cases?
Magnesium's combination of low density (1,738 kg/m³), good strength, excellent electromagnetic shielding, and heat dissipation makes it ideal for portable electronics. AZ91D die castings achieve thinner walls than aluminum at lower weight, and magnesium naturally shields RF/EMI better than plastic.
What are bioabsorbable magnesium implants?
WE43 magnesium alloy implants (screws, plates, stents) gradually dissolve in the body over 12–24 months as bone heals, eliminating the need for removal surgery. Magnesium is biocompatible, and the corrosion products (Mg²⁺ ions) are naturally metabolized. This technology is now commercially approved for orthopedic screws in Europe.