An homogenous distribution of body-centered cubic FeCo soft phase with a grain size of 20 to 30nm was demonstrated in annealed Sm–Co/Fe bulk samples via energy-filtered transmission electron microscopy. Quantitative Co/Fe interdiffusion measured using both energy dispersive spectroscopy and parallel electron energy loss spectroscopy gave Fe60±5%Co40±5% for the magnetically soft body-centered cubic phase and Sm2(Co0.82Fe0.18)7 and Sm(Co0.80Fe0.20)5, respectively, for the magnetically hard phases in these two alloy systems after optimal annealing. The graded interface develops in both samples due to the Co/Fe interchange between the hard and soft phases and the body-centered cubic soft phase was determined.

Microstructure and Intergranular Diffusion in Exchange-Coupled Sm–Co/Fe Nanocomposites. Y.Zhang, M.J.Kramer, C.Rong, J.P.Liu: Applied Physics Letters, 2010, 97[3], 032506