Atom probe study on the bulk nanocomposite SmCo/Fe permanent magnet produced by ball-milling and warm compaction

The microstructure and compositions of the bulk nanocomposite SmCo/Fe permanent magnet were studied using transmission electron microscopy and 3-dimensional atom probe techniques. The excellent magnetic properties were related to the uniform nanocomposite structure with nanometer α-Fe particles uniformly distributed in the SmCo phase matrix. The α-Fe phase contained ∼26 at% Co, and the SmCo phase contained ∼19 at% Fe, confirming that the interdiffusion of Fe and Co atoms between the two phases occurred. The formation of the α-Fe(Co) phase explained why the saturation magnetization of the nanocomposite permanent magnet was higher than that expected from the original pure α-Fe and SmCo5 powders, which enhanced further the maximum energy product of the nanocomposite permanent magnet.

► A uniform nanocomposite SmCo/α-Fe permanent magnet with high performance obtained. ► The first quantitative analyses of interdiffusion of Fe and Co between the two phases presented. ► The saturation magnetization of the nanocomposite enhanced by the resulting α-Fe(Co) phase.