Syntesis of Al-Al2O3 Nanocomposite by Mechanical Alloying and Evaluation of the Effect of Ball Milling Time on the Microstructure and Mechanical Properties

Aluminum matrix composites reinforced by nano-ceramic particles are widely used in military, airplane and automotive industries because of their high strength, modulus, wear resistance and low thermal expansion coefficient. However, low ductility and toughness have limited their applications. This research focuses on production of Al–Al2O3 nanocomposite materials by mechanical alloying method and evaluation of the milling time on their microstructures and mechanical properties. In this regard, Al-5wt%Al2O3 powders were ball milled at different times and microstructure of specimens were studied by SEM. Also, mechanical properties like: hardness, compression strength and ductility of the specimens were determined after pressing and sintering. Study of the microstructures indicated that more uniform distribution of nano-size alumina particles in aluminum matrix can be achieved by increasing of milling time. The results of hardness and compression tests showed that hardness, strength and ductility increased by augment of milling time. I