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