Effects of Fe fine powders doping on hot deformed NdFeB magnets

•The doped Fe powders have little influence on the c-axis alignment of magnets.•The elongated Fe powders are more than the spherical Fe powders in the magnets.•The corrosion resistance is improved effectively with the increasing Fe fraction.•The bending strength is enhanced by the elongated α-Fe phase embedded in the matrix.

The composite NdFeB magnets with blending melt-spun flakes and Fe fine powders were prepared by the hot-pressed and hot-deformed route. Characterizations of the hot-deformed NdFeB magnets affected by the doped Fe powders were tested. The doped Fe powders decrease the hot-deformed pressure when the strain is between 15 and 50%. XRD patterns show that the doped Fe powders have little influence on the c-axis alignment of hot-deformed NdFeB magnets in the press direction. The Br and the (BH)max get improved when the doped Fe powders are less than 3 wt%. The doped Fe of hot-deformed NdFeB magnets exists in the elongated state and the spherical state surrounded by the Nd-rich phase. With the Fe fraction increasing, the potential of magnet moves to the positive direction and the diameter of the Nyquist arc becomes larger, which indicate that the corrosion resistance improved effectively. The bending strength was enhanced by the elongated α-Fe phase embedded in the matrix 2:14:1 phase.