Characterization of nanostructured Mg-Cu-Ni powders prepared by mechanical alloying

In this investigation, nanocrystalline Mg55Cu40Ni5 alloy has been synthesized from the elemental powders by mechanical alloying (MA). Microstructural evolution, morphological changes and thermal behaviour of the mechanically alloyed powders at different stages of milling have been examined by a combination of differential scanning calorimetry (DSC), scanning electron microscopy with energy-dispersive X-ray detection ((SEM/EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The crystallite size of Mg55Cu40Ni5 alloy estimated with broadening of XRD peaks by Williamson-Hall and Debye Scherrer formulas. In order to confirm the crystallite size obtained by XRD, the microstructure of the mechanically alloyed powder was also monitored by TEM. The results showed that after 50 h of milling time nanostructured alpha-Cu(Mg,Ni) solid solution, MgO and Mg0.85Cu0.15 phases whose crystallite sizes are below 20 nm were obtained. According to SEM/EDX results, the elemental powder particles which were initially of different size, shape, and distribution became uniform, confirming the compositional homogeneity of the Mg55Cu40Ni5 alloy and particle size decreased rapidly with increasing milling time. (C) 2014 Elsevier B.V. All rights reserved.