Microstructure and magnetic properties of hot worked Nd-Fe-B magnets

摘要

We introduce unusual method of manufacturing high-energy Nd-Fe-B magnets by hot working cast alloy. Magnets were prepared by hot multidirectional treatment. Castings were extruded and upset at 900 deg C. Electron microscopy, metallographic and X-rays studies were performed on rare-earth magnets. Average grain size of the main phase is 20 mum. It was found that easy magnetization is formed at the angle of 30 deg to axis of deformation. Appearance of unusual angle of axis of magnetic texture is connected with two competitive deformation processes. A two-step heat treatment at 950 deg C and 480 deg C improved magnetic properties of all samples. Moderate energy product 220 kJ/m~3, H_cJ=820 kA/m, B_r=1.02 T was obtained.