Enhanced Soft Magnetic Properties of CoNi-Based High Entropy Alloys

High entropy alloys (HEA) based on CoNi systems contain of Mn, Cr, and Al elements were prepared through mechanical alloying and subsequent annealing method. The structural and magnetic properties of CoNi alloy system were discussed based on the results of X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and vibrating sample magnetometer (VSM) analysis methods. There were different chemical compounds formed in CoNi-Mn-Cr samples, while a simple solid solution phase with FCC or BCC structural evolved in CoNiMnCrAl high entropy alloy after mechanical milling and subsequent annealing process at 750 and 900 °C. This sample exhibited excellent soft magnetic properties with the saturation magnetization and coercivity of about 31 emu/g and 39 Oe, respectively, after annealing at 750 °C. Annealing at 900 °C could improve soft magnetic properties of CoNiMnCrAl high entropy alloy in the range of 58 emu/g for saturation of magnetization and 18 Oe for coercivity due to the formation of a single solid solution phase with BCC structure.