Modeling and Limits of Advanced HT-Magnets

Thomas Schrefl, Josef Fidler, and Werner Scholz

IEEE Trans Magn., 36 (2000) 3394-3398.

This paper combines microstructural investigations using transmission electron microscopy with micromagnetic finite element simulation of the magnetic domain wall pinning behavior of novel Sm(Co, Fe, Cu, Zr)7 4 8 0 permanent magnet materials applicable up to 550 C. A finite element method was used to simulate domain wall pinning in SmCo5 /Sm2 Co17 based permanent magnets. The finite element model was built-according to the cellular microstructure obtained from TEM investigations. The numerical results show a strong influence of the dimension of the cell boundary phase on the coercive field, which significantly increases with the extension of the 1 : 5/7-type cell boundary phase. The calculated values of the coercive field are in the range from 1000 2000 kA/m assuming a cell size varying from 80 160 nm. The difference of the magnetocrystalline anisotropy between cell boundary and cell interior phases is determined by the Cu-content of the magnet. Due to the lower Curie temperature of the Cu-containing cell boundary phase high coercive fields are obtained at elevated temperatures ( >400 C)

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Apr. 23, 2001