Magnetic behaviour of nanocrystalline Cu-Fe-Co/Al2O3 composite powders obtained by mechanical alloying

The effects of Al2O3 addition on structural and magnetic property changes during mechanical alloying of Cu, Fe and Co element powders were studied systematically by X-ray diffraction, superconducting quantum interference device (SQUID) and magnetic force microscopy (MFM). Milling the powders for up to 10 h leads to the progressive diffusion of Co and Fe atoms into the Cu. Face-centered cubic Cu(Fe, Co) phases with coherent diffraction domains (cdd) size of similar to 35 nm were prepared by mechanically alloying Cu0.5Fe0.25Co0.25 with and without Al2O3 powder (1%, 3% and 10%). The effect of crystal size on magnetic properties was studied. Mechanically alloyed metallic-ceramic composite powder showed lower saturation magnetization than the metallic system but enhanced coercive field. Milling time significantly affects the structure, composition, magnetic properties, and magnetic domains for both metallic and composite systems. (C) 2013 Elsevier B.V. All rights reserved.