Structural and Magnetic Properties of Ordered/Disordered Sendust Powders Prepared by Mechanical Alloying

In this study, Sendust alloy (Fe85Si9.6Al5.4) was fabricated by mechanical alloying process, and its crystal structure and magnetic properties were investigated. Sendust alloy has excellent soft magnetic properties and is widely used in different applications. Raw materials (Fe, Si, and Al) were milled by a planetary ball mill at different milling times, from 5 to 20 h. The resulted alloys were annealed at 1373 and 1473 K for 2 h, and the effect of annealing temperature was investigated on the magnetic properties. Crystal structure of the samples was investigated by X-ray diffractometery method. The results indicated that saturation magnetization of 10-h milled sample was at maximum, and it decreased both by increasing milling time and by annealing. These variations were discussed based on phase transformation from ordered to disordered phases and/or vice versa. The maximum saturation magnetization obtained, 156 emu/g, was comparable by those reported for Sendust alloy, which was prepared by other methods. Magnetization-temperature curves of the alloys and annealed ones were recorded by a Faraday balance. Two clear drops were observed on each M-T curve of the as-milled samples that displayed the existence of two different magnetic phases. On the other hand, there is just one drop on the M-T curves of the annealed samples, indicating that these samples were in a less disordered phase.