Partial coercivities of coercivity-distributed Nd-Fe-B sintered magnets at high temperatures

摘要

The Grain Boundary Diffusion processed Nd-Fe-B sintered magnets show a distribution of coercivity, and the partial coercivities at the maximum operating temperature are much important to estimate the demagnetization behavior in motor applications. The temperature dependence of partial coercivities in the coercivity-distributed magnets was examined and the temperature coefficients of coercivity (β) were compared with those of the conventional magnets. The β values of both of partial coercivity and coercivity of the whole magnet for the coercivity-distributed magnets exhibit the same tendency as that of the conventional magnet with the same coercivity. Using β values of the conventional magnets and the partial coercivities at room temperature, partial coercivities at high temperatures can be calculated to obtain a coercivity distribution at the temperatures. Coercivity of the whole magnet at high temperatures can be simulated as well.