Phase composition and magnetic properties in hot deformed magnets based on Misch-metal

Highlights: • The nanocrystalline isotropic magnets with "a" ≥20% show two curie temperature. • Coercivity could still keep 1114.08 kA/m in the magnet when the MM content is 30%. • The double MSS main phases are due to the inhomogeneous distribution of RE element. • The poor La, Ce RE-rich phase is good for the formation of plate-like grains. In this paper, the Rare-earth Iron Boron (RE-Fe-B) magnets were fabricated successfully by using the double main phase method through mixing the Neodymium Iron Boron (Nd-Fe-B) powders and Misch-metal Iron Boron (MM-Fe-B) powders with different ratio. Aiming at the nanocrystalline RE₂Fe₁₄B magnets prepared by using spark plasma sintering technology, phase structure and magnetic properties were investigated. It is found that the Misch-metal (MM) alloys promote the domain nucleation during the the process of magnetization reversal and then damage the coercivity (H_cj) of isotropic RE₂Fe₁₄B magnets, while the H_cj could still remain more than 1114.08 kA/m when the mass proportion of MM (simplified as: "a") is 30%. Curie temperature and phase structure were also researched. Two kinds of mixed-solid-solution (MSS) main phases with different Lanthanum (La) and Cerium (Ce) content were believed to be responsible for the two curie temperature of the RE₂Fe₁₄B magnets with "a" ≥20%. This is resulted from the inhomogeneous elemental distribution of RE₂Fe₁₄B phase.