Effect of Process Temperature on the Sm2Fe17 Alloying Process During a Reduction-Diffusion Process Using Fe Nanopowder

This study investigated the effect of process temperature on the alloying process during synthesis of Sm2Fe17 powder from ball-milled samarium oxide (Sm2O3) powders and a solid reducing agent of calcium hydrides (CaH2) using iron nanopowder (n-Fe powder) by a reduction-diffusion (R-D) process. The n-Fe-Sm2O3CaH2 mixed powders were subjected to heat treatment at 850~1100°C in Ar-H2 for 5 h. It was found that the iron nanopowders in the mixed powders are sintered below 850°C during the R-D process and the SmH2 is synthesized by a reduced Sm that combines with H2 around 850°C. The results showed that SmH2 is able to separate Sm and H2 respectively depending on an increase in process temperature, and the formed Sm2Fe17 phase on the surface of the sintered Fe nanopowder agglomerated at temperatures of 950~1100°C in this study. The formation of the Sm2Fe17 layer is mainly due to the diffusion reaction of Sm atoms into the sintered Fe nanopowder, which agglomerates above 950°C. We concluded that nanoscale Sm2Fe17 powder can be synthesized by controlling the diffusion depth using well-dispersed Fe nanopowders. (Received July 5, 2010)