Improvement of magnetic properties of nanostructured Ni79Fe16Mo5 alloyed powders by a suitable heat treatment

The supermalloy (Ni79Fe16Mo5) nanostructured powder with average crystallite size of about 8 nm was prepared by high energy milling. The obtained powders were characterized by X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and vibration sample magnetometer. The results showed that the coercivity and the saturation magnetization reach about 8 Oe and 75 emu/g at 96 h and become approximately 1 Oe and 85 emu/g after a suitable heat treatment, respectively. The magnetic measurements confirmed that the supermalloy soft magnetic nanostructure powder was produced by mechanical alloying followed by a post heat treatment. The results revealed that a small amount of Mo element remain in the system up to 96 h due to (i) high fusion temperature, Tf = 2893 K, (ii) high mechanical hardness, (iii) low solubility of Mo into Ni at low temperatures in mechanical alloying conditions.