Nano-scale AlN powders and AlN/Al composites by full and partial direct nitridation of aluminum in solid-state

Full and partial nitridation of Al powders were obtained by heating commercial pure Al powders at different temperatures for different time under pressure-less H₂ and N₂ atmosphere. Then the fully nitrided powders were wet ball milled to prepare AlN powders while the partially nitrided powders were consolidated, and then extruded into AlN/Al composites. In-situ formation of AlN on the surface of Al powders was successfully controlled in the nitridation process. AlN dispersoids transformed from particle-like to needle-like, and finally to fully reacted AlN clusters consisted of their nano-scale fine particles. As a result, AlN powders with a mean particle size of about 200 nm and a purity of 98.63 wt% could be prepared, and AlN/Al composites with adjustable combinations of strength and elongation can be fabricated as well.