Magnesium alloys are engineered materials based on magnesium as the primary element, alloyed with aluminum, zinc, manganese, zirconium, rare earths, yttrium, silver, and other elements to overcome the limitations of pure magnesium.
They are the lightest structural metallic alloys used in engineering today, offering exceptional strength-to-weight ratio, vibration damping, and machinability.
Major Alloying Elements & Their Roles
| Element | Typical Range | Metallurgical Role |
|---|---|---|
| Magnesium (Mg) | Balance | Base metal |
| Aluminum (Al) | 2 – 9% | Strengthening, castability |
| Zinc (Zn) | 0.5 – 6% | Strength & corrosion resistance |
| Manganese (Mn) | 0.2 – 1% | Improves corrosion resistance |
| Zirconium (Zr) | 0.2 – 1% | Grain refinement |
| Rare Earths (RE) | 1 – 6% | High-temperature strength |
| Yttrium (Y) | 2 – 5% | Creep resistance |
| Silver (Ag) | 1 – 3% | High-temp precipitation |
| Silicon (Si) | 0.5 – 1.5% | Creep resistance (casting alloys) |
Mechanical Properties (Wrought Alloys)
| Alloy | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
|---|---|---|---|
| AZ31 | 250 – 275 | 150 – 200 | 10 – 18 |
| AZ61 | 290 – 320 | 200 – 240 | 8 – 12 |
| AZ80 | 320 – 350 | 220 – 260 | 6 – 10 |
| ZK60 | 320 – 360 | 230 – 280 | 10 – 15 |
| WE43 | 350 – 410 | 240 – 300 | 8 – 14 |
Cast Magnesium Alloys
| Alloy | Tensile Strength (MPa) | Yield Strength (MPa) |
|---|---|---|
| AZ91D | 230 – 260 | 150 – 170 |
| AM60 | 220 – 250 | 130 – 150 |
| AE42 | 200 – 240 | 130 – 160 |
Physical Properties
| Property | Typical Value |
|---|---|
| Density | 1.74 – 1.85 g/cm³ |
| Melting Point | ~600 – 650 °C |
| Elastic Modulus | 43 – 46 GPa |
| Thermal Conductivity | 70 – 160 W/m·K |
| Electrical Conductivity | 25 – 40% IACS |
| Damping Capacity | Very high |
| Magnetic Behavior | Non-magnetic |
Key Characteristics
✔ Lightest structural alloy family
✔ High specific strength
✔ Exceptional vibration damping
✔ Excellent machinability
✔ High thermal conductivity
✔ Recyclable and energy-efficient
Applications
Automotive
Gear housings, steering wheels, seat frames, transmission cases
Aerospace
Aircraft brackets, helicopter components, gearbox housings, space structures
Electronics
Laptop & phone frames, EMI shielding housings, heat sinks
Industrial & Defense
Lightweight tooling, robotic arms, missile structures
Advantages
✔ 30–35% lighter than aluminum
✔ Excellent strength-to-weight ratio
✔ Superior vibration damping
✔ Outstanding machinability
✔ Fully recyclable
Limitations
❌ Lower modulus than aluminum
❌ Corrosion sensitivity
❌ Limited cold workability
❌ Fire risk in chips and fines
❌ Higher cost for RE alloys
Why Choose Magnesium Alloys?
Choose magnesium alloys when extreme lightweighting, high specific strength, vibration reduction, machining efficiency, and performance per kilogram drive the design decision.