Phase structure, magnetic properties, and magnetization behavior of Sm(Co,Zr)(7)/alpha-(Fe-Co) nanocomposite made by mechanical alloying

The Sm(Co,Zr)(7)/alpha-(Fe-Co) nanocomposite permanent magnets are produced by mechanical alloying and subsequent annealing. The soft magnetic phases were introduced by two different processes. In the first process, the crushed as-cast SmCo6.8Zr0.2 powders were blended and milled with different weight percent of fine iron powders (SCZ+Fe) and in the second process, the crushed as-cast (SmCo6.8Zr0.2)(1-x)Fe-x (x=0, 0.1, 0.25, 0.5, 0.75) powders (SCZF) were milled directly. XRD analysis showed that the phase structure of annealed SCZ+Fe are consisted of SmCo7 phase and alpha-(Fe,Co) phase, while the composites of annealed SCZF are composed of alpha-(Fe,Co) and SmCo hard phases that varied with different Fe content. The best energy product of the annealed SCZF and SCZ+Fe are 11.3 MGOe (SCZF-3) and 10 MGOe (SCZ+Fe-1), respectively, resulting from the very strong exchange coupling between the hard phase and the soft phase. According to the Henkel-plots of SCZF-3 and SCZ+Fe-1, a stronger intergrain exchange coupling effect was observed in SCZF-3 sample. The irreversible nucleation fields of SCZF-3 and SCZ+Fe-1 are also studied in detail. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3334459