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Gas atomisation: inert gas (argon or nitrogen) stream shatters a molten metal stream — produces highly spherical powders with low oxygen content; preferred for AM (additive manufacturing) and MIM (metal injection moulding). Applications: titanium alloys (Ti-6Al-4V), nickel superalloys (IN718, IN625), stainless steels (316L). Water atomisation: high-pressure water jet — irregular morphology, lower cost, higher oxygen; used for iron, stainless steel, and copper powders for PM and MIM. Plasma atomisation: RF plasma melting — highest sphericity and purity; premium grade for aerospace AM applications. Electrolytic production: cathode deposition — used for copper and iron powders; very high purity and low apparent density. Carbonyl process: thermal decomposition of metal carbonyls — produces ultra-fine (<10 µm) spherical carbonyl iron (CIP) and carbonyl nickel powders; used in MIM, magnetic cores, and EMI shielding.

Metal powder particle size is characterised by the volume-weighted cumulative distribution: D10 (10% of particles finer than this diameter), D50 (median diameter), D90 (90% of particles finer). For SLM/LPBF additive manufacturing: typical specification 15–53 µm (D10 ~15, D50 ~30, D90 ~53); coarser powders (45–106 µm) for EBM (electron beam melting). For PM press-and-sinter: 45–150 µm D50 range. For MIM: D50 5–20 µm with narrow distribution. For thermal spray: 45–75 µm for HVOF; 75–125 µm for APS plasma spray. ASTM B214 (sieve analysis) and ASTM B822 (laser diffraction, Mastersizer) are standard test methods. Request laser diffraction PSD report (Dv10, Dv50, Dv90) and SEM images to confirm sphericity and satellite content.

PM (Powder Metallurgy) grades: press-and-sinter iron and steel powders from Höganäs, GKN Hoeganaes — irregular morphology, high green strength; MIM grades — fine (<20 µm), can be water- or gas-atomised; cemented carbide (WC-Co) grades from Sandvik, Kennametal. AM (Additive Manufacturing) grades: tight PSD control (15–53 µm for L-PBF), high sphericity (>90% spherical), low oxygen (<1,000 ppm for reactive metals), excellent flowability (Hall Flow <30 s/50 g per ASTM B213). AM powder costs are significantly higher than PM: AM-grade Ti-6Al-4V from $200–500/kg vs PM-grade from $50–150/kg. AM powders require traceability certification including powder lot number, production date, chemical analysis, PSD, flowability, apparent density, and oxygen content per ASTM B213–B215.

Fine metal powders are combustible and can form explosive dust clouds (dust explosion, Class St1–St3). Key ATEX considerations: minimum ignition energy (MIE) for aluminium powder is as low as 1–10 mJ (extreme sensitivity); titanium and magnesium powders are pyrophoric below certain particle sizes. ATEX Directive 2014/34/EU requires explosion-proof equipment in dust cloud zones (Zone 20/21/22 for dust). Storage and handling requirements: inert atmosphere (argon or nitrogen purge) for reactive metal powders (Ti, Al, Mg); earthing and bonding for static dissipation; spark-resistant scoops and transfer tools; ATEX-rated dust extraction and filtration (HEPA for fine metallic dust); segregation from ignition sources. GHS Class 4.1 (flammable solids) labelling required for aluminium and magnesium powders. Never use water extinguisher on burning metal powder — use Class D (dry sand, dry graphite) fire suppressant.