Berlin 2018 – scientific programme

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MA: Fachverband Magnetismus

MA 32: Micromagnetism and computational magnetics

MA 32.5: Talk

Wednesday, March 14, 2018, 16:00–16:15, H 0112

ab-initio phase stabilities of Ce-based hard magnetic materials — •halil ibrahim sözen, fritz körmann, tilmann hickle, and jörg neugebauer — Max-Planck-Institut für Eisenforschung, D-40237 Düsseldorf, Germany

Due to the developments in electrical transportation and renewable energies, hard magnetic materials composed of rare earths (RE) and transition metals (TM) have gained increasing importance in the last decades. Recently, there are attempts to develop alternative hard magnetic materials, RE-TM-X (X=Ti, W, Mo, Si, Al), that lift the dependence on a small number of RE elements. In order to support the efforts to find alternative materials concepts for hard magnetic applications, we performed ab initio calculations of finite temperature phase stabilities of Ce-based alloys. The Helmholtz free energy F(T,V) is calculated for all relevant competing phases using a sophisticated set of methods capturing vibrational, electronic, magnetic and configurational entropy contributions. The study includes unary Ce, binaries of Ce-Fe and Fe-Ti phases, and ternary Ce-Fe-Ti phases, for which the performance of our approach for rare-earth metals is tested. Theoretical results are compared with experimental findings. We observe that the presence of the CeFe2 phase retards any formation of promising hard magnetic Ce-Fe-Ti alloys. The study has therefore been extended to the impact of quaternary alloying elements such as Cu, La and Ga, in order to provide strategies to solve this challenge.