Tuning the hard magnetic properties of nanocrystalline Ce-Fe-B alloys by Ho substitution

Abstract

• Paramagnetic CeFe 2 phase is suppressed by Ho substitution. • Ho tends to enter into 2:14:1 phase in melt-spun Ce-Fe-B alloy. • Coercivity of Ce-Fe-B alloy is greatly enhanced with Ho substitution. • Ho-substituted Ce-Fe-B alloy has better thermal stability. To improve the performance of Ce-based magnets and take full advantages of heavy rare earth (RE) element of Holmium, Ce-Fe-B alloys with different Ho substitutions were prepared by melt spinning. Their phase constitution and magnetic properties have been systematically studied. Ho can enter into the main phase to form (Ce,Ho) 2 Fe 14 B phase, and the introduction of Ho can suppress the formation of CeFe 2 phase in the (Ce 1- x Ho x ) 14 Fe 80 B 6 alloys. Partial Ho substitution can tune the magnetic properties of RE-rich (Ce 1- x Ho x ) 14 Fe 80 B 6 alloys and single-phase (Ce 1- x Ho x ) 12 Fe 82 B 6 alloys. For RE-rich (Ce 1- x Ho x ) 14 Fe 80 B 6 alloys, the intrinsic coercivity H cj , Curie temperature T c and thermal stability are greatly improved by Ho substitution. H cj reaches a high value of 1317.7 kA/m at x = 0.5. For single phase alloy, ( BH ) max greatly increases from 18.7 kJ/m 3 to 56.1 kJ/m 3 when x increases from 0 to 0.3. The microstructure observation of (Ce 0.7 Ho 0.3 ) 14 Fe 80 B 6 alloy indicates the formation of (Ce,Ho) 2 Fe 14 B and RE-rich phases, and Ho prefers to enter 2:14:1 phase than Ce. This work suggests the possibility of developing cost-effective permanent magnets based on Ce and Ho elements.