Effect of Process Temperature on the Sm_2Fe_(17) Alloying Process During a Reduction-Diffusion Process Using Fe Nanopowder

摘要

This study investigated the effect of process temperature on the alloying process during synthesis of Sm_2Fe_(17) powder from ball-milled samarium oxide (Sm_2O_3) powders and a solid reducing agent of calcium hydrides (CaH_2) using iron nanopowder (n-Fe powder) by a reduction-diffusion (R-D) process. The n-Fe-Sm_2O_3-CaH_2 mixed powders were subjected to heat treatment at 850-1100 °C in Ar-H_2 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 SmH_2 is synthesized by a reduced Sm that combines with H_2 around 850 °C. The results showed that SmH_2 is able to separate Sm and H_2 respectively depending on an increase in process temperature, and the formed Sm_2Fe_(17) phase on the surface of the sintered Fe nanopowder agglomerated at temperatures of 950-1100 °C in this study. The formation of the Sm_2Fe_(17) 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 Sm_2Fe_(17) powder can be synthesized by controlling the diffusion depth using well-dispersed Fe nanopowders.