Effects of Sintering Temperature on Microstructure and Magnetic Properties of Nd–Fe–B Magnets

Abstract

The sintered Nd-Fe-B (neodymium-iron-boron) magnet has been used for many applications in various fields such as acoustics, communications, and automation due to its excellent properties including high remanence, high coercivity, and large energy product. Especially high-coercivity sintered Nd-Fe-B magnets have been extensively applied in the field of permanent magnet motors. In the present work, the effects of sintering temperature on the structural and magnetic properties of a Nd15Fe77B8-type magnet have been investigated. Sintered permanent magnets were produced from a Nd15Fe77B8 commercial alloy. The magnetic properties were evaluated using an Automatic Magnet Tester. The magnets were successfully produced at different temperatures. It was seen that the best magnetic properties were obtained for the magnet produced at 1050 degrees C for 1 h. The structural evolution of the magnets has also been examined by means of X-ray diffraction (XRD) and polarized optical microscope. Nd2Fe14B, Fe3B and some alpha-iron phases were observed by X-ray diffraction results.