Preparation of Sm₂Fe₁₇ alloy by reduction–diffusion process

Sm₂Fe₁₇ alloy is the intermediate material for the preparation of Sm₂Fe₁₇N _x (x ≈ 3); thus, the synthesis of pure Sm₂Fe₁₇ mother alloy is the key to obtaining high-performance Sm₂Fe₁₇N _x . Reduction–diffusion (R–D) is a cost-effective method. In this study, the R–D process of synthesizing Sm₂Fe₁₇ was analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and X-ray fluorescence (XRF). Furthermore, the influences of the tightness of compacted reactants, the compensation amount of Sm₂O₃, and the particle size of Fe on the formation of Sm₂Fe₁₇ were discussed from the aspects of the three raw materials. The results show that Sm reduced from Sm₂O₃ reacts with Fe particles to form intermetallic compound Sm₂Fe₁₇ directly in the R–D reaction process of preparing Sm₂Fe₁₇; the generation of Sm and its migration to the surface of Fe particles control the reaction rate; a proper tightness of compacted reactants is necessary for ensuring the purity of Sm₂Fe₁₇ product; pure Sm₂Fe₁₇ can be obtained when the compensation of Sm₂O₃ is 33 % of the stoichiometry; and the sufficiency of the reaction improves with the decrease in the size of Fe powders under the same reaction condition.