Effect of Milling Time on Structural Evolution and Mechanical Properties of Garnet Reinforced EN AW6082 Composites

The morphology, structure, and hardness variations of garnet reinforced EN AW6082 Al-alloy composites have been investigated. High-energy ball milling of EN AW6082 Al-alloy powder, with and without garnet reinforcement, was performed under argon atmosphere for various duration, i.e., up to 50 hours. The study aimed at exploring the role of alloying elements and hard reinforcement particles on the structural evolution at different stages of mechanical milling. The composite powders were characterized in terms of the morphological variation, microstructural evolution, and thermal stability. Conventional microindentation and nanoindentation measurements were carried out on the individual powders as well as composite particles to estimate the changes in the mechanical properties of the composites with milling time. The results reveal that incorporation of hard garnet particles hastens the milling effect and leads to significant improvement in hardness and modulus of unreinforced pure aluminum and aluminum alloy. This work has demonstrated the possibility of producing composites from industrial by-product, with properties better than those of aluminum alloys and aluminum-based composites. (C) The Minerals, Metals & Materials Society and ASM International 2014