|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Materials Science for High-Performance Permanent Magnets
||Tailoring the Coercive Field of Grain Boundary Engineered Magnets: A Nanoanalytical TEM and Micromagnetic Simulation Study
||Josef Fidler, Gregor Alexander Zickler, Ahmad Asali
|On-Site Speaker (Planned)
The role of grain boundary (GB) phases of Nd-Fe-B based magnets, whose composition, thickness and magnetic properties primarily control the coercive field, have extensively been studied during the last 30 years. Local changes of the anisotropy field and demagnetizing field at/near intergranular phases considerably reduce the overall coercive field. Nowadays, new nanoanalytical TEM/STEM techniques with atomic resolution allow the creation of precise microstructural models suitable for the numerical micromagnetic calculation of the coercive field of an individual magnet whose microstructure strongly depends on the processing parameters and nominal composition. The present study with special emphasis on nanoanalytical, high resolution EELS characterization compares different microstructures: large grained sintered heavy rare earth free magnets with an anisotropic compositional behaviour of GBs parallel and perpendicular to the alignment direction and nanocrystalline magnets with directly de-coupled or coupled grains obtained by rapidly quenching, which are widely used for bonded and hot deformed type magnets.