A new method for synthetizing nanocrystalline aluminium nitride via a solid–gas direct reaction

Abstract

Herein, we describe a new method for preparing AlN powder by milling aluminium powder at room temperature under a flowing NH3 gas atmosphere. The initial aluminium powder has a mean particle size of 80.5μm. During mechanical alloying, NH3 decomposed at room temperature and N was incorporated into the aluminium crystal lattice. A subsequent heat treatment of the milled powders under vacuum for 1h resulted in the formation of substantial amounts of AlN. Two different heat treatment temperatures have been tested (650 and 1000°C).Different milling runs were carried out to evaluate the influence of the milling duration on the amount of AlN formed. Quantification by XRD indicated that the AlN amount that was formed was strongly influenced by the milling time. The heat-treated powders, which were milled for 25h, led to a significant amount of nanocrystalline AlN (i.e., higher than 97wt.%).