本项目针对纳米复合永磁材料发展面临的软磁相结构和硬磁相晶体取向的同时控制这个关键科学问题，将室温高压扭转变形（HPTD）和高压热压缩（HPTC）相结合，开展组合式极端变形下NdFeB/a-Fe纳米复合永磁材料的制备、结构和性能调控研究。通过室温HPTD在NdFeB非晶基体中引入晶粒尺寸小（5-7 nm）、分布均匀的高分数（> 30%）a-Fe相，制备含软磁纳米晶的NdFeB非晶前驱物，以控制软磁相的晶粒尺寸、分布和含量。采用HPTC产生高应力(~1GPa)和大应变(>80%)，研究极端变形下NdFeB非晶前驱物的晶化转变和纳米晶的取向生长。研究组合式极端变形对软磁相结构和硬磁相晶体取向的同时控制；揭示HPTC变形下Nd2Fe14B纳米晶择优生长的机制。研究所制备的纳米复合永磁材料的界面结构和磁性。建立“变形工艺/成分－微结构－磁性”的关系，发展高性能纳米复合永磁材料制备的新原理和新技术。

In this project, to overcome the conflicting requirements for rational control of the microstructure of soft-magnetic nanograins, such as grain size, phase distribution and fraction, and the alignment of hard-magnetic nanograins in nanocomposite magnets, the fabrication and microstructural control of nanocomposite magnets will be carried out with the combination of High-Pressure Torsion Deformation (HPTD) and High-Pressure Thermal Compression (HPTC). First, Nd-Fe-B amorphous precursor containing uniformly distributed soft-magnetic a-Fe phase (5-7 nm in diameter and > 30 wt%) will be fabricated using the HPTD at room temperature. Then, the amorphous precursor will suffer from the HPTC that yields high stress (up to ~1GPa) and large strain (>80%). The crystallization transformation and preferential growth of Nd2Fe14B nanograins in the amorphous matrix under HPTC will be investigated. With such a combined extreme deformation, the simultaneous control of the alignment of hard-magnetic Nd2Fe14B nanograins and the microstructures of soft-magnetic a-Fe phase will be studied. The underlying mechanism of the grain alignment of Nd2Fe14B under HPTC will be revealed. The interfacial structure of synthesized bulk nanocomposite magnets will be characterized and their magnetic properties will be studied. Based on these investigations, the "deformation processing and compositions- microstructure - magnetic properties" relationship will be established, and new approaches and principles will be created for the fabrication of high-performance bulk nanocomposite magnets.