Improvement of coercivity and microstructure of Nd_14.73Fe_78.67B_6.60 melt-spun ribbons by addition of Zn

Abstract

The microstructures and magnetic properties for melt-spun ribbon of typical composition (Nd_14.73Fe_78.67B_6.60)_100-xZn_x (x= 0, 1, 2 and 3) have been studied. We have found that the coercivity was greatly enhanced and microstructure was sensitively influenced by addition of Zn. For Nd_14.73Fe_78.67B_6.60 magnets with 1 at% Zn addition, the coercivity at room temperature was enhanced from 16 kOe to 20.2kOe. The highest magnetic properties such as remanence (B_r), coercivity (_iH_c), and maximum energy product [(BH)_max] were 7.54 kG, 21 kOe, 12 MGOe, respectively. TEM and EDAX studies revealed that Nd-rich phases were well distiributed along the grain boundaries and Zn concentration is increased around grain boundaries. In addition, XRD showed the formation of NdZn₂ phase. The improvement of a coercivity by the Zn addition is believed to be due to good distribution of Nd-rich phase and the appearance of NdZn₂.