Beneficial effect of nonmagnetic Y on magnetic properties due to the enhancement of exchange coupling in nanocomposite (Nd,Y)2Fe14B/α–Fe magnets

We have studied the nanocomposite magnets with nominal compositions of Nd8-xYxFe88B4 (x=0-4.0) by mechanical milling techniques and subsequent heat treatment. We find that there exists the beneficial effect of nonmagnetic Y substitution for magnetic Nd on magnetic properties in nanocomposite magnets. The extension of the exchange coupling length, due to a decrease of the anisotropy of the hard-magnetic phase, results in that more soft-magnetic grains participate well in the exchange coupling, improving the magnetic properties of the nanocomposite magnets. (C) 2002 American Institute of Physics.