Direct synthesis of AlN and Al-AlN composites by room temperature magneto ball milling: The effect of milling condition on formation of nanostructures

This study describes a novel route for low temperature synthesis of AlN and Al-AlN composites. This method is based on mechanically activated reactions (mechanofusion) between Al and nitriding gas. The mechanofusion was performed using milling device with magnetically controlled ball movement. Al powder was milled in nitrogen or ammonia. In the former case, cold welding was predominant leading to formation of hollow spheres. Nitriding reaction occurred during milling of Ar powder in ammonia. Depending on the milling condition two different reactions were created: (1) direct synthesis of AlN compound and (2) formation of nanostructures composed of Al, N and H atoms, which were subsequently transformed into AlN upon heating below the melting point of Al. The structure of as-milled and annealed AlN and AlN-Al samples was investigated using x-ray diffractometry. Differential thermal analysis was performed on as-milled samples.