Magnesium powder and granules are finely divided forms of metallic magnesium engineered for high reactivity, rapid oxidation, and controlled energy release. Unlike bulk magnesium used as a structural material, powders and granules are selected for their chemical, thermal, and metallurgical behavior.
Because surface area dominates performance, particle size, purity, morphology, and oxide control are more critical than conventional mechanical strength.
Chemical Composition
| Element | Typical Content (%) |
|---|---|
| Magnesium (Mg) | 99.5 – 99.95 |
| Aluminum (Al) | ≤ 0.05 |
| Zinc (Zn) | ≤ 0.02 |
| Manganese (Mn) | ≤ 0.03 |
| Iron (Fe) | ≤ 0.005 |
| Copper (Cu) | ≤ 0.01 |
| Nickel (Ni) | ≤ 0.001 |
| Surface Oxygen | Controlled |
Particle Size Classification
| Form | Typical Size Range |
|---|---|
| Granules | 0.5 – 5 mm |
| Coarse Powder | 200 – 500 µm |
| Fine Powder | 50 – 200 µm |
| Ultra-fine Powder | < 50 µm |
| Flake / Atomized Powder | Variable |
Metallurgical & Crystallographic Behavior
Crystal Structure: Hexagonal Close-Packed (HCP)
Microstructure consists of α-magnesium grains with a thin MgO/Mg(OH)₂ surface layer.
Metallurgical Insight:
In powder form, magnesium performance is governed by surface chemistry and diffusion
kinetics rather than bulk mechanical properties.
Key Mechanical Properties (Bulk Reference)
| Property | Typical Value |
|---|---|
| Tensile Strength | 90 – 110 MPa |
| Yield Strength | 20 – 35 MPa |
| Elastic Modulus | ~45 GPa |
| Hardness | ~30 HB |
| Ductility | Low at room temperature |
Physical Properties
| Property | Value |
|---|---|
| Density (solid) | 1.74 g/cm³ |
| Apparent Density (powder) | 0.3 – 1.2 g/cm³ |
| Melting Point | 650 °C |
| Boiling Point | 1090 °C |
| Ignition Temperature | ~450 – 630 °C |
| Heat of Combustion | ~25 MJ/kg |
| Burning Temperature | ~3100 °C |
Oxidation & Combustion Behavior
Burns with an intense white light, producing magnesium oxide ash. Reaction rate is strongly dependent on particle size:
Granules → slower, controlled reaction
Fine powders → rapid ignition and flash combustion
Refining & Production Processes
Powder Production Methods
Atomization in inert atmosphere
Mechanical milling of turnings
Granulation and size classification
Conditioning
Oxide control, inert handling, anti-caking treatments, oil-coating or passivation
Processing, Storage & Safety
Handled under inert gas or mineral oil to avoid ignition. Stored in airtight containers in dry environments.
Fire Safety:
Class D metal fires only — water must never be used.
Dry sand or Class D extinguishers are mandatory.
Available Forms
Granules
Coarse to ultra-fine powders
Flakes
Pellets & briquettes
Oil-coated and passivated powders
Applications
Pyrotechnics & Defense
Flares, flash powders, incendiaries, tracer ammunition
Metallurgical Industry
Steel desulfurization, deoxidation, nodular cast iron treatment
Chemical Industry
Grignard reagents, reduction reactions, specialty chemicals
Aerospace & Electronics
Rocket ignition systems, EMI shielding composites, getter materials
Advantages
✔ Extremely high energy-to-weight ratio
✔ Fast, controllable combustion
✔ Strong reducing power
✔ Lightweight and efficient
✔ High purity and size control
✔ Recyclable material
Limitations
❌ Highly flammable in fine form
❌ Sensitive to moisture and air
❌ Requires strict handling protocols
❌ Not suitable for structural use
❌ Regulated in certain applications
Why Choose Magnesium Powder & Granules?
Magnesium powder and granules are chosen when performance depends on reaction kinetics, energy release, and chemical reactivity rather than mechanical strength.