Structure and intrinsic magnetic properties of MM2Fe14B (MM=La, Ce, Pr, Nd) alloys

Abstract

MM33Fe66B (MM=La, Ce, Pr, Nd) alloys (mass ratio) were prepared by induction melting and heat-treated at 1353 K for 24 h to produce homogeneous MM2Fe14B phase. The phase structure and element distribution of the alloys were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The alloys were applied ball milling to obtain powders with good size distribution and then magnetic aligned in a static magnetic field of 2 T for 4 h, in order to achieve the intrinsic magnetic properties by vibrating sample magnetometer (VSM). XRD results showed that the alloys were composed of the single 2:14:1 main phase and RE-rich phase, which was similar to Nd2Fe14B structure. Magnetic measurements showed that the saturation magnetization (Ms) and anisotropy field (HA) of the MM33Fe66B alloy were 11.3 kGs and 48.4 kOe, respectively, demonstrating its good potential as permanent magnets. The Curie temperature of the MM33Fe66B alloy was determined as 502.9 K by magnetization-temperature curves. Microstructure observation showed that Nd and Pr were mainly in the 2:14:1 ferromagnetic phase, while La and Ce prefered to aggregate in the RE-rich grain boundary phase, which is beneficial to fabricating (Pr, Nd, MM)2Fe14B magnets with good magnetic properties.