Soft ferromagnetism in nanostructured mechanical alloying FeCo-based powders

FeCo-based nanostructured powders were prepared by mechanical alloying and subsequently heat treated in an attempt to optimize their magnetic properties. Although the annealed powders had grain sizes smaller than the magnetic exchange length, a low coercivity, H C, as expected from Herzer's model, did not occur. All the possible causes for the larger than expected H C were analyzed. The magnetic measurements on the dilute and concentrated powder samples, as well as the temperature dependence of the magnetic properties from 10 to 300 K, indicate that the degree of magnetic interaction between the individual powder particles, along with the particle morphology and size, causes the relatively high H C of 10-20 Oe at room temperature