Crystallization kinetics of Ti-doped Nd2Fe14B/a-Fe nanocomposite permanent magnets br

Nanocomposite magnet consisting of a fine mixture of magnetically hard and soft phase has received muchattention for potential permanent magnet development. One of the important requirements for alloys to exhibitexcellent magnetic properties is a nanocrystalline grain size. The soft and hard magnetic phases cansimultaneously achieve ideal nanoscale composites. The effect of Ti additions in the amorphous crystallizationprocess of the exchange-coupled nanocomposite Nd2Fe14B/a-Fe magnet prepared by melt spinning isinvestigated. The results show that Ti can change the crystallization kinetics of the NdFeB melt-spun ribbons.The Ti can increase the activation energy of a-Fe and contrarily reduce the activation energy of a metastable1 : 7 phase, so the growth speed of a-Fe decreases and the metastable 1 : 7 phase can stably precipitate from theamorphous phase. When the annealing temperature increases, a metastable 1 : 7 phase is decomposed into the a-Fe phase and the Nd2Fe14B phase. The microstructure observation shows that the grains of the alloys dopedwith Ti are fine and uniform, with an average grain size of about 20 nm, and no particularly large a-Feparticles appear. The optimal magnetic property is (BH)max = 12 MGmiddotOe (1 G = 10-4 T, 1 Oe = 79.57795 A/m)when Ti addition is 1.0%

Automated summary

Nanocomposite magnet composed of magnetically hard and soft phases has potential for permanent magnet development. The addition of Ti in the crystallization process of the Nd2Fe14B/a-Fe magnet can change the crystallization kinetics and result in the formation of fine and uniform grains with an average size of about 20 nm. The optimized magnetic property is (BH)max = 12 MGmiddotOe when Ti addition is 1.0%.