Die-upset Nd 11.5Fe 72.4Co 9Nb 1B 6.1 magnets with additions of Zn, Al and Sn

Abstract

The magnetic properties and microstructure were studied for bulk Nd 11.5Fe 72.4Co 9Nb 1B 6.1 magnets synthesized by hot-pressing and subsequent die-upsetting the melt-spun ribbons with additions of three kinds of low-melting-point metal (Zn, Al and Sn). Die-upset Nd 11.5Fe 72.4Co 9Nb 1B 6.1 magnets have low magnetic properties since they have an inhomogeneous microstructure with many coarse grains. The microstructure of die-upset magnets remains almost unchanged with Al and Sn additions, which only have negative effects on the magnetic properties. Different from Al and Sn additions, Zn addition changes the phase composition of the starting melt-spun powers due to the reaction of Zn and Nd 2Fe 14B during hot-pressing and hot-deforming and enhances the development of the desired [0 0 1] texture and improves the microstructure of die-upset magnets. As a result, an anisotropic magnet with good maximum energy product (221 kJ/m 3) and high coercivity (670 kA/m) is obtained by adding 2 wt% Zn to the Nd 11.5Fe 72.4Co 9Nb 1B 6.1 alloy.