Evolutions during synthesis of Al-AlN-nanostructured composite powder by mechanical alloying

High-energy milling technique was used to synthesize Al-10 wt.% AlN-nanostructured composite powder in a planetary ball-mill under argon atmosphere up to 25 h. To show the role of AlN particles, process was conducted for monolithic aluminum. The changes in powder characteristics were investigated by time. Microstructure of powders was studied after different milling times by scanning electron microscope (SEM). The morphological evolutions showed that relative equiaxed powder could be synthesized after 25 h milling. Structural analysis was performed by X-ray diffraction method (XRD) to determine the grain sizes and lattice strain. Furthermore, particle size analysis (PSA) revealed the distribution curvatures. The compressibility behavior of milled powders was studied at different compaction pressures which involve the rearrangement and plastic deformation stages. The modified Heckel equation was used to consider the pressure effect on yield strength as well as reinforcing role of hard AlN particles. (c) 2007 Elsevier B.V. All rights reserved.