Lean neodymium Nd–Fe–B magnets containing minor addition of titanium

The effect of titanium addition on the structure and magnetic properties was studied for the nanocomposite Nd 7 Fe 79– x B 14 Ti x and Nd 8 Fe 78– x B 14 Ti x systems. The alloys were rapidly solidified by melt‐spinning with the roll speed 20 m/s. The overquenched, amorphous ribbons were subsequently crystallization annealed for 20 min at 953–973 K. It was found that the addition of 2 and 4 at% of Ti leads to a substantial increase of the coercivity and maximum energy product of the nanocomposite magnets while maintaining the remanence unchanged. The highest properties were obtained for the alloys containing 4 at% of Ti. The maximum energy product of 143 kJ/m 3 was achieved for the Nd 8 Fe 74 B 14 Ti 4 alloy. The TEM studies showed substantial differences in the morphology of the alloys. The ternary alloys contain grains of various sizes of approximately 300 nm. The alloys containing 4 at% of Ti exhibit more homogeneous structure with the crystal sizes up to 30 and 50 nm for the Nd 8 Fe 74 B 14 Ti 4 and Nd 7 Fe 75 B 14 Ti 4 alloys, respectively. More detailed information on the phase constitution was obtained from the Mössbauer spectroscopy. Comparison of the Ti‐free and 4 at% Ti alloys revealed that the amount of the hard magnetic Nd 2 Fe 14 B phase decreases from 84.53 to 69.88% for the Nd 7 Fe 79– x B 14 Ti x system and increased from 66.60 to 82.48% for Nd 8 Fe 78– x B 14 Ti x system.