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

Abstract

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 °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.