Defect Manipulation for the Coercivity Enhancement of Nd-Fe-B Permanent Magnets

Abstract

The demand for rare-earth based permanent magnets is expected to rise for various climate friendly technologies. This motivates for the search of better designed permanent magnets with optimal use of rare-earth elements without compromising the key magnetic properties. We simulate Nd$_2$Fe$_{14}$B based permanent magnet to study the effects of microstructure on coercivity ($H_{\rm C}$). We demonstrate a fast method to compute the microstrucutral parameters in numerical micromagnetics. We report a novel  magnetic reversal process, which is primarily driven by defect thickness. By selective replacement of the defect with a hard magnetic phase $H_{\rm C}$ is expected to rise by 1.5 times to that of single grain model with soft defect. This study is extended to a multigrain polycrystal model. Our systematic approach helps in identifying specific microstructural features pertinent for enhancement of coercivity. This work provides implications for future work to design improved defect engineered permanent magnets for green technologies.

Keywords: Coercivity, Magnetization, micromagnetics, Defects, permanent magnets