Analysis of Thermal Demagnetization Behavior of Nd–Fe–B Sintered Magnets Using Magnetic Domain Observation

We used magnetic domain observation to statistically observe the thermal demagnetization behavior of Nd–Fe–B sinteredmagnets at elevated temperatures up to 150 °C. Simultaneous magnetization reversal in a hundred adjacent grains occurred at 90 °C because of the magnetic interaction among the grains beyond grain boundaries in the Dysprosium (Dy)-free low-coercivity magnet. Conversely, simultaneous magnetization reversal in a hundred grains did not occur in the Dy-added high-coercivity magnets, and the demagnetizing ratio steadily increased with temperature. Furthermore, the addition of Dy induced high thermal stability by eliminating the simultaneous thermal demagnetization, which was caused by the magnetic interaction among the grains

Analysis of Thermal Demagnetization Behavior of Nd–Fe–B Sintered Magnets Using Magnetic Domain Observation

We used magnetic domain observation to statistically observe the thermal demagnetization behavior of Nd–Fe–B sinteredmagnets at elevated temperatures up to 150 °C. Simultaneous magnetization reversal in a hundred adjacent grains occurred at 90 °C because of the magnetic interaction among the grains beyond grain boundaries in the Dysprosium (Dy)-free low-coercivity magnet. Conversely, simultaneous magnetization reversal in a hundred grains did not occur in the Dy-added high-coercivity magnets, and the demagnetizing ratio steadily increased with temperature. Furthermore, the addition of Dy induced high thermal stability by eliminating the simultaneous thermal demagnetization, which was caused by the magnetic interaction among the grains

Ab initio vibrational free energies including anharmonicity for multicomponent alloys

A density-functional-theory based approach to efficiently compute numerically exact vibrational free energies - including anharmonicity - for chemically complex multicomponent alloys is developed. It is based on a combination of thermodynamic integration and a machine-learning potential. We demonstrate the performance of the approach by computing the anharmonic free energy of the prototypical five-component VNbMoTaW refractory high entropy alloy