Impact of soft magnetic α‐Fe in hard Nd2Fe14B magnetic materials: A micromagnetic study

Abstract The striving for the independence of fossil energy sources by further development of renewable energies as well as the change in mobility act as a driving force on technological innovations. Magnetic materials with improved magnetic efficiency help to push the limits for optimized, low‐loss power conversion applications and electrification. Besides improving the chemical composition, that is, gaining better performance using alloys reduced or free of heavy rare earth elements, microstructure optimization has proven to be a crucial field of research. In order to better control the grain size, phase distribution and texture of the polycrystalline material, new process routes, such as severe plastic deformation, need to be investigated and explored in addition to the state‐of‐the‐art method – sintering. Here, attention must be paid to the possible formation of soft magnetic α‐Fe after the casting process prior to the actual deformation step, as these secondary phases negatively affect the hysteretic behavior of the magnet. Assistance in the analysis of the underlying magnetic mechanisms is provided by micromagnetic theory. Besides the reliable prediction of the magnetization distribution on micron‐scale, especially in a multi‐phase microstructure, it also allows for the analysis of the magnetic hysteresis behavior. This work provides a micromagnetic simulation frame work based on a finite element scheme. Relying on this framework the effective hysteresis behavior of two different heterogeneous microstructures (Nd 2 Fe 14 B and Nd 2 Fe 14 B/α‐Fe) are analyzed and compared.