Magnetic behavior of nanocrystalline Cu-Ni-Co alloys prepared by mechanical alloying and isothermal annealing

The structural and magnetic properties of nanocrystalline Cu-Ni and Cu-Ni-Co alloys prepared by mechanical alloying and subsequent isothermal annealing in the temperature range of 350-650 degrees C has been investigated systematically. The average grain sizes of Cu-Ni and Cu-Ni-Co alloy systems were found to be in the range of 5-8 nm after 30 h of milling and 21-40 nm after isothermal annealing of as-milled samples. Here, it is shown that the magnetic properties (H-c, M-r and M-s) of the nanocrystalline alloys undergo changes by the variation in microstructural constituents, grain size and evolution of phases. The alloy containing 10 wt% Co shows notable improvement in the magnetic properties. Phases present in the ball milled samples and the isothermally annealed ball milled product were identified and characterized by X-ray diffraction (XRD) and differential scanning calorimetric (DSC) techniques and the results were correlated with the magnetic properties of the alloys. (C) 2007 Elsevier B.V. All rights reserved.