Synthesis and morphological aspects of AlN whiskers from Al powders obtained by spark discharged process

Synthesis of AlN whiskers from Al powders obtained by a spark discharged process and their morphology were studied. AlN whiskers were synthesized by nitridation of the compositions in the Al-C system in N₂-gas flow at 1450°C for 24 hours. Morphological aspects of the whiskers were observed by a scanning and a transmission electron microscopes. Al powders obtained by the spark discharged process were covered with a thin layer of hydroxide and did not melt nor coalesce up to 1000°C in air. Morphologies of the synthesized whiskers were divided into three types; two single filament types and one bicrystal type. Both of the single filament whiskers had 〈0001〉 growth direction. The growth direction of the latter type deviated about 13 degrees from 〈0001〉 axis. All the whiskers were thin plate-like. The internal defect of whiskers was also described.