The irreversible flux loss due to exposure to an elevated temperature was evaluated systematically for nanocomposite magnets with various coercivity values. It was found that the short-term and long-term flux losses in some nanocomposite magnets are smaller than in a conventional isotropic Nd-Fe-B magnet despite their small coercivity values. The origins of the observed small values for flux loss were studied by using the proposed model. It was clarified that the observed small values for the short-term flux loss in the nanocomposite magnets can be attributed to the squareness of a demagnetization curve of the nanocomposite magnets not deteriorating at an elevated temperature. The small values for the irreversible susceptibility of the nanocomposite magnets reasonably explained their small values for long-term flux loss.
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