High performance anisotropic NdFeB magnets prepared by dual-alloy die-upsetting

The anisotropic nanocrystalline magnets were produced by hot pressing and die-upsetting the mixed powders of MQU-F and MQU-G with a mass ratio of x: 1-x (x = 0-1). With x increasing from 0 to 1, the intrinsic coercivity (H-ci) decreased from 22.7 to 15.0 kOe, and the remanence (B-r) and maximum energy product ((BH)(max)) ascended from 12.6 to 13.5 kG and from 38.0 to 44.1 MGOe respectively. The XRD patterns showed that (006), (105), and (008) peaks were strengthened, indicating that easy axes of the grains were aligned along the hot-deformation direction. Fine plate-like grains were observed by field emission scanning electron microscope. The components of the magnets prepared from the blends behaved in a cooperative way, which made the demagnetization curves a smooth profile. Both initial magnetization and demagnetization curve were measured. Additionally, the magnetization mechanism and magnetization behaviors were also analyzed. (C) 2012 American Institute of Physics. [doi:10.1063/1.3679866]