Synthesis of size-controlled and dispersible Sm2Fe17N3 magnetic particles by reduction diffusion process using molten salt

Abstract

The synthesis of size-controlled Sm2Fe17 magnetic particles is a prerequisite for the fabrication of high-performance Sm2Fe17N3 permanent magnetic materials. Here, Sm2Fe17 was synthesized using a cost-effective reduction-diffusion method. The calcium chloride molten salt was introduced to control the particle size and achieve a single phase of Sm2Fe17. The effects of reduction-diffusion reaction temperature and the amount of added calcium chloride on the phase constitution and microstructure of the final product of reduction-diffusion were systematically investigated. Adding an appropriate amount of calcium chloride can effectively inhibit the overgrowth and sintering of the reduced particles. By employing the strategy of adding 20 wt% of calcium chlorides into the green compacts, we were able to successfully synthesize uniform Sm2Fe17 particles that are well-dispersed, with an average size of 2.2 μm. Furthermore, by combining the optimal reduction-diffusion conditions and the nitriding process, the hard magnetic Sm2Fe17N3 material was successfully obtained. This study could be useful for the development of high-performance Sm2Fe17N3 magnetic materials utilizing reduction-diffusion technology.