Improved magnetic properties and optimized preparation process of (MM)–Fe–B magnets

Substitution of Nd element with misch metal (MM) element in the RE–Fe–B magnets has been set off as an effective method to decrease the cost of RE–Fe–B materials and ensure a more balanced utilization of rare-earth elements. In the present work, the composition of MM x Fe 94 −x B 6 ( x = 14 and 16) alloys are fabricated by the melt-spinning method with wheel speeds of 20 and 25 m s −1 , respectively. It is demonstrated that with increasing wheel speed and MM content, can effectively suppress the formation of α-Fe soft phase and refine grain size. The maximum energy product ( BH ) max of 10.03 MGOe is obtained for the MM16-V25 alloy, which is a result of its higher intrinsic coercivity H cj ( H cj : 9.15 kOe) and squareness H k / H cj ( H k / H cj : 0.49). Meanwhile, the analysis of Henkel plots δM ( H ) and microstructure show that the MM16-V25 alloy obtains the strongest exchange coupling effect and more uniform microstructure with fine grain size. In addition, the compositions of 2:14:1 grain and grain boundary from energy dispersive spectroscopy for the MM16-V25 alloy are also discussed in detail.