A Comparative Study of the Synthesis and Thermal Stability of Nanostrucrured Al and Al-Mg Powders Fabricated by Mechanical Alloying Technique

Nanostructured Al and Al-Mg (Mg 30 wt. %) powders with the mean crystallite sizes of 42 and 11 nm were prepared through the solid state ball milling technique. The milling process was performed for various times up to 12 h in argon atmosphere and the synthesized powders were in detail characterized by different techniques. The effect of milling time and Mg addition on the size, morphology, chemical composition, phase structure and crystallite size of the powder particles were thoroughly investigated and the results were compared with the non-alloyed Al system. Two distinct particle morphologies comprising lamellar flakes and solid granules were obtained as final milling products in Al and Al-Mg systems, respectively. It was revealed that Mg atoms gradually diffuse into the Al lattice during milling and form a supersaturated Al-Mg solid solution (α phase). Thermal analyses of the powders revealed that metastable nanostructures formed during the milling transform into the equilibrium and stable phases such as Al4C3 and Al2Mg3 (β) upon the heating.