This study investigates the synthesis of SmFe intermetallic compounds by a solid state reduction-diffusion process (R-D process) using a mixture of Sm2O3-CaH2 ball-milled powders and Fe nanopowders. The Sm2O3-CaH2-Fe mixed powders were subjected to heat treatment under a switched gas atmosphere from Ar-5 vol.%H2 to a vacuum atmosphere during the R-D process at 800 οC. It was found that the SmFe intermetallic phases of Sm2Fe17 and SmFe3 were effectively formed in a switched gas atmosphere and observed on the surface of the sintered Fe nanopowder agglomerate. This formation occurred because the sintering of agglomerated Fe nanopowders occurred at a low temperature of about 500 οC earlier before the Sm dissociated from SmH2 was diffused into the sintered Fe nanopowders agglomerate during the R-D process. The Sm2Fe17 phase of the target alloy was identified having a rhombohedral Th2Zn17-type (2:17 R) structure with a grain size of 400-800 nm. It is expected that the Sm2Fe17 nanopowders can be effectively fabricated by controlling the initial powder characteristics such as size refinement and mixing homogeneity.

Keywords: Samarium oxide, Intermetallic compounds, Nanocrystalline, Reduction-diffusion process, Permanent magnets, Microstructure, Powder metallurgy.