Mechanically alloyed AlN particle-reinforced Al-6061 matrix composites: Powder processing, consolidation and mechanical strength and hardness of the as-extruded materials

This work investigates the use of mechanical alloying to produce aluminium AA6061 matrix composite powders reinforced with AlN, and the relationship among the stages of mechanical alloying, the powder characteristics, and the mechanical strength and hardness of the consolidated materials. The results showed that the brittle particles accelerate the milling process by increasing the matrix deformation and enhancing the welding and the fracture of particles. Moreover, the morphology and the structure of the powder, which changes with mechanical alloying, influence the powder compressibility and extrudability. The elimination of pre-existent cracks of the reinforcement particles, the smaller particle size and its better distribution throughout the matrix, associated with the strain hardening and oxide dispersion produced by milling, brought an about 100% increase in the ultimate tensile strength and hardness, as compared with conventionally mixed composites of the same composition.