Regensburg 2019 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 11: Focus Session: Magnetic materials for energy efficient applications

MA 11.1: Hauptvortrag

Montag, 1. April 2019, 15:45–16:15, H38

Microstructure optimization for rare-earth efficient permanent magnets — •Thomas Schrefl1, Johann Fischbacher1, Alexander Kovacs1, Lukas Exl2, Kazuya Yokota1,3, and Tetsuya Shoji31Danube University Krems, Austria — 2Wolfgang Pauli Institute, c/o University of Vienna, Austria — 3Toyota Motor Corporation, Japan

Permanent magnets are widely used in modern society including consumer electronics, transport, and power generation. The key figures of merit, coercive field and energy density product, depend on the interplay between the intrinsic magnetic properties and the microstructure. We use synthetically generated grain structures to model the influence of grain morphology and grain boundary phases on coercivity. By computing the lowest saddle point for magnetization switching we find the weakest point in the structure, where magnetization reversal starts. We apply machine learning to quantify the reduction of coercivity caused by different microstructural features. Again, regions where the local coercive field is much lower than the average can be identified. Our results suggest that adding heavy rare-earth elements through grain boundary diffusion to these specific regions only will be sufficient to increase coercivity. Thus, the magnet’s performance and temperature stability may be improved with a minimum amount of heavy rare-earth elements. Examples will be given for Nd2Fe14B and SmFe11Ti based magnets.

Work supported by Toyota Motor Corporation and the Austrian Science Fund (grant no F41, P31140).

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