Construction of high performance nanocomposites based on a shape anisotropic soft phase: A micromagnetic simulation study.

Nanocomposite permanent magnets are considered as a strong candidate for the next generation of high-performance permanent magnet materials due to their ultra-high theoretical magnetic energy product. In this paper, a nanocomposite theoretical model based on the shape anisotropy of the soft phase (Fe₆₅Co₃₅) is constructed to guide the improvement of coercivity, the lack of which has become a critical problem in improving the performance of Nd-Fe-B nanocomposites further. The results of micromagnetic simulation show that adding a shape anisotropic soft phase to nanocomposites can effectively improve coercivity, delay nucleation during the magnetization reversal process, and help obtain a demagnetization curve with high squareness. When the length size of the soft phase d_s ≤ 21 nm and the aspect ratio of the soft phase I = 5 for the Nd₂Fe₁₄B/Fe₆₅Co₃₅ nanocomposites, almost square demagnetization curves can be obtained, particularly when d_s = 21 nm, the size of the soft phase is 21 × 21 × 105 nm³, the content of the soft phase is 42.1 vol. %, and the Nd₂Fe₁₄B/Fe₆₅Co₃₅ nanocomposite achieves a maximum magnetic energy product of 94.4 MGOe. In addition, the results also show that, compared with the cubic nanocomposite model (I = 1), the larger size of the soft phase can be accommodated into the nanocomposites by the addition of shape anisotropy, on the premise of ensuring the soft–hard coupling effect. Our design provides a new strategy and approach for preparing high-performance nanocomposite permanent magnets. [ABSTRACT FROM AUTHOR]