Investigation of Mechanical Properties of Aluminum Matrix Nanocomposites via Well-Distributed Al12Mg17 Complex Metallic Alloy Nanoparticles Using Mechanical Milling

This paper investigates the effect of milling time on the microstructural changes, density, and mechanical properties of Al-5 wt.% Al12Mg17 nanocomposite. In this study, aluminum matrix nanocomposites, reinforced by the nanoparticles of a novel Al12Mg17 complex metallic alloy, were synthesized via high-energy planetary ball milling and hot-pressing processes. Powder characterization showed the morphology and size change of nanocomposite mixture to form large flakes during the first 20 h of milling time, and then the particle size reduced. Investigation of hot-pressed samples with different milling times revealed that increasing the milling time reduced the interparticle spacing, and, consequently, a uniform dispersion of Al12Mg17 nanoparticles in the Al matrix was achieved after 30 h of ball milling. Well-distributed nanoparticles led to more effective crystalline growth during the hot pressing. With increasing the milling time up to 30 h, the hardness and compressive strength of the nanocomposites continuously increased, because of smaller crystalline sizes and also well-distributed nanoparticles, and then declined due to the deteriorating effect of porosities. Based on microstructural factors, density, and mechanical properties, the optimum milling time of 30 h was determined for nanocomposite fabrication.