Influence of zirconium addition on the microstructure and magnetic properties of nanocomposite Nd10.1Fe78.2-xCo5ZrxB6.7 permanent magnets

Nanocomposite Nd10.1Fe78.2-xCo5ZrxB6.7 (x = 0, 1.5, 2.5, 2.7, 3, 4) permanent magnets were prepared by melt-spun and annealing. The microstructure and magnetic properties of the permanent magnets were investigated. The results reveal that the addition of Zr element significantly reduces the grain size and improves the thermal stability of the amorphous phase. A fine nanocomposite microstructure with an average grain size of about 35 nm can be developed at a wheel speed of 16 m·s−1 with the content of Zr up to 2.7 at. %. After optimal annealing (710°C × 4 min), the magnetic properties of the Nd10.1Fe75.5Co5Zr2.7B6.7 bonded magnets were achieved as follows: Br= 0.72 T, jHc = 769 kA·m−1, and (BH)max = 85.0 kJ·m−3.