Fabrication of Ni, Si and Mg Supersaturated Solid Solutions in Al by Mechanical Alloying

In this work, a comparison between the synthesis process of nanostructured Al base alloys modified with Si, Ni and Mg and the formation of their respective supersaturated solid solution is presented. The samples were obtained via Mechanical Alloying (MA) at a speed of 300 RPM for 2, 5, 10, 20 and 30 h under an inert Ar atmosphere. Lattice parameter evolution, semiquantitative X-Ray Diffraction Analysis and SEM micrographs were correlated to determine the attained solubility in the Al matrix. The results showed that powder refinement and solubility rates are directly affected by the hardness of the solute element and the limiting solubility in equilibrium state respectively. Therefore the Al-Mg alloy achieved the highest solubility of the samples after 10 h of milling, meanwhile, the Al-Si alloy showed the lowest solubility even after 20 h of milling. Microstructural analyses by X-Ray Diffraction revealed that the lattice parameter showed different behavior depending on the alloy system, in some cases showing a deviation from the behavior predicted by Vegard's law. Finally, this work demonstrates that the successful synthesis of supersaturated solid solutions via MA is dependent on the alloy system as well as milling conditions.