The Boron-Rich Phase and Its Behaviour in Nd-Fe-B Magnet

The boron-rich phase in Nd-Fe-B magnet was studied by means of HVEM, Mossbauer spectroscopy, X-ray diffraction and magnetic measurements. The chemical formula of the boron-rich phase can be represented by Nd_1+εFe₄B₄. It is composed of two interpenetrating substructures, both have tetragonal symmetry. Since two substructures have different periods in $\vec C$ direction, the boron-rich phase may belong to the compositional incommensurate structure in one dimension. It is paramagnetic at room temperature and may behave as the pinning sites in the magnet. The observation results by HVEM of micrOstructure of Nd-Fe-B alloy at different temperature are also given. The coercivity mechanism is discussed coupling with the reported results.