Microstructure and intergranular diffusion in exchange-coupled Sm-Co/Fe nanocomposites

We demonstrate homogenous distribution of bcc FeCo soft phase with grain size of 20-30 nm in the annealed Sm-Co/Fe bulk samples by energy filtered transmission electron microscopy (EFTEM). Quantitative Co/Fe interdiffusion measured using both energy dispersive spectroscopy (EDS) and parallel electron energy loss spectroscopy (PEELS) shows Fe60 +/- 5%Co40 +/- 5% for the magnetically soft bcc phase and Sm-2(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 bcc soft phase was determined. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3467202]