Study of the densification of a nanostructured composite powder - Part 1: Effect of compaction pressure and reinforcement addition

The compressibility behavior of Al-AlN nanostructured composite powder with different amount of reinforcement content was studied. The composite powder was synthesized by blending and high-energy milling process for 25 h. Williamson-Hall method was applied to determine the crystallite size after milling process. To investigate the role of reinforcement particles in consolidation of composite powders, monolithic aluminum powder was examined. Samples were made at different pressures and relationships were established between the compaction pressure and the density of the compacts. The modified Heckel equation was used to assume the pressure effect on yield strength and then was compared with other common equations. The best correlation was obtained when the effect of compaction pressure was considered. Due to lower plastic deformation capacity, the powders with higher content of hard reinforcements exhibited lower compressibility. The results also revealed that the yield strength of compacts, predicted by the mathematical equation, increases with reinforcement addition. (c) 2007 Elsevier B.V. All rights reserved.