Magnetic and structural studies of mechanically alloyed (Fe50Co50)62Nb8B30 powder mixtures

Amorphous (Fe50Co50)62Nb8B30 powder mixture was prepared by mechanical alloying from elemental Fe, Co, B and Nb powders in a planetary ball mill under argon atmosphere. Structural, thermal and magnetic properties were performed on the milled powders by means of X-ray diffraction, differential scanning calorimetry and magnetic measurements. The amorphous state is reached after 125 h of milling. The excess enthalpy due to the high density of defects is released at temperature below 300 °C. Crystallisation and growth of crystal domains are the dominating processes at high temperatures. The saturation magnetisation decreases rapidly during the first 25 h of milling to about 15.24 A m2/kg and remains nearly constant on further milling. Coercivity, Hc, value of about 160 Oe is obtained after 125 h of milling.