Abstract:Five kinds of bonded magnets with the compositions (at%) of Nd10.5Fe78.4-xCo5ZrxB6.1 (x= 0, 1.0, 1.5, 2.0, 2.5) were prepared by melt-spinning, post heat treatment and mould pressing. The microstructure and crystallization behavior was studied by X-ray diffraction (XRD), differential thermal analysis (DTA) and transmission electron microscopy (TEM). The results suggest that high Zr concentration can increase the glass formation ability (GFA) of alloys. The Fe2Zr with high melting point forms in the alloys, when the content of Zr is controlled at a certain amount, and it can reduce the grain size. The coercivity and the squareness of demagnetization loop are obviously improved by the addition of Zr, and the energy product is accordingly increased. As a result, the excellent magnetic properties with Br= 0.659 T, Hcj=628 kA/m, Hcb=419 kA/m, (BH)m=73 kJ/m3 are obtained in Nd10.5Fe78.4-xCo5ZrxB6.1 bonded magnet with x=2.