Microstructure-Property Relationships in Sm-Fe-N-Based Permanent Magnets

具有间隙氮的钐铁化合物（Sm-Fe-N）是一类具有与Nd-Fe-B永磁体相竞争的磁性材料。本项目旨在实现两个相互关联的目标：(1)通过加工和合金开发来控制sm - fe - n基永磁体的微观组织演变；(2)建立sm - fe - n基永磁体的微观结构与磁性能之间的关系。主要关注的是晶界、第二相和晶粒尺寸对磁性能的影响。为了控制组织演变，设计了能够有效促进快速凝固过程中钐铁化合物形成的合金。合金添加物，如Ti、Zr、Si、V、C及其组合，用于改变Sm-Fe合金的凝固行为。目标是在较低的凝固速率下增强Sm-Fe化合物的形成，或者完全抑制结晶相的形成。在后一种情况下，所得的非晶材料结晶为Sm-Fe化合物。随后的氮化形成硬磁Sm-Fe-N相。本课题重点研究钐铁氮基永磁体的微观结构与磁性能之间的关系。与Nd-Fe-B磁铁相比，Sm-Fe-N材料最显著的优势是居里温度（约高150摄氏度），允许在更苛刻的热环境中应用。然而，Sm-Fe-N磁体面临许多挑战，特别是在智能处理和对微观结构-性能关系的理解方面。＊＊＊

9714946 Shield Samarium-iron compounds with interstitial nitrogen (Sm-Fe-N) comprise a promising class of magnetic materials with properties competitive to those of Nd-Fe-B permanent magnets. This project seeks to accomplish two interrelated objectives: (1) to control the microstructure evolution in Sm-Fe-N-based permanent magnets through processing and alloy development; (2) to establish relationships between the microstructure and magnetic properties in Sm-Fe-N-based permanent magnets. Of primary concern is the influence of grain boundaries, second phases, and grain size on the magnetic properties. To control microstructure evolution, alloys are designed that effectively enhance the formation of the samarium-iron compound during rapid solidification processing. Alloying additions, such as Ti, Zr, Si, V, C, and combinations of these, are used to alter the solidification behavior of Sm-Fe alloys. The goal is to either enhance the formation of the Sm-Fe compound at lower solidification rates or to suppress the formation of crystalline phases altogether. In the latter case the resultant amorphous materials are crystallized to the Sm-Fe compound. Subsequent nitrogenation results in the hard magnetic Sm-Fe-N phase. The relationships between the microstructure and magnetic properties of Sm-Fe-N-based permanent magnets should be clarified in this project. %%% The most notable advantage of Sm-Fe-N materials over Nd-Fe-B magnets is the Curie temperature (approximately 150 degrees C higher) allowing applications in more demanding thermal environments. However, Sm-Fe-N magnets pose many challenges, especially with regards to intelligent processing and understanding of the microstructure-property relationships. ***