Both fall under this heading, but the physical form differs: powders are typically granular or spherical particles produced by atomization, while flakes are thin, lamellar particles produced by milling. The distinction matters commercially — flakes are preferred for metallic coatings and pigments, while spherical powders are used in additive manufacturing and energetic applications — but both classify together at the SITC level.

Fine aluminum powders can be classified as flammable solids under DOT and IATA/IMDG hazardous-materials regulations, requiring proper packaging, labeling, and documentation. Importers should confirm the particle size and surface-treatment specifications with their supplier and consult a licensed customs broker or freight forwarder experienced in hazmat shipments.