The effect of Nd8Cu2 alloy on the microstructure and magnetic properties of (Nd, MM)-Fe-B sintered magnets

Abstract Multi-main-phase (MM 0.3 Nd 0.7 )-Fe-B (MM = Misch Metal) magnets were prepared by sintering the mixture of Nd-Fe-B and MM-Fe-B powders. In order to further enhance the coercivity of the magnet, Nd 8 Cu 2 eutectic alloy powders were added to the magnets as a variable. When the addition of the Nd 8 Cu 2 powders increases from 0 to 5 wt%, the H cj of the magnets increases by 56.8% (7.01–10.99 kOe). Microstructural investigations show that after the addition of 5 wt% Nd 8 Cu 2 powders, the thickness of continuous grain boundary layers are over 2.1 nm, which effectively block the short-range exchange coupling between adjacent grains, contributing to the improvement of H cj . The Selected Area Electron Diffraction images show that the Cu exists in the form of NdCu 2 in the grain boundary layers.