Microstructure, Magnetic Properties, and Electrical Resistivity of Nd-Fe-B/NdF3 Composite Magnets

Nd-Fe-B/NdF₃ composite magnets have been prepared by two different mixing methods: 1) mixing in agate mortar without lubricant and 2) milling in a planetary ball mill with heptane. The comparison of two mixing methods and their influences on the electrical and magnetic properties of the Nd-Fe-B/NdF₃ composite magnets have been investigated. The results show that the microstructures of the composite magnets fabricated by mixing in agate mortar without lubricant were not uniform. But method 1 contributed a better magnetic property compared with method 2. The electrical resistivities of the Nd-Fe-B/NdF₃ composite magnets fabricated by method 1 in the direction parallel to the pressing direction increased with increasing NdF₃ amounts. The remanence and maximum energy products of the Nd-Fe-B/NdF₃ composite magnets prepared by method 1 reduced to some extent with increasing NdF₃ amount. Method 2 contributed to obtaining a more homogenous microstructure. Method 2 has little influence on the electrical resistivity when the amounts of NdF₃ were kept constant. But, it is detrimental to the magnetic properties of the composite magnets.