Effects of magnetic field and annealing on the structure and magnetic properties of Alnico ribbons

• Published in: Journal of alloys and compounds 2019-05, Vol.785, p.715-724
• Main Authors: Han, Xu-hao, Sun, Ji-bing, Liu, Tian-yu, Wang, Hong-wei, Zhang, Ying, Cui, Chun-xiang
• Format: Article
• Language: English
• Subjects: Annealing; Magnetic fields; Magnetic properties; Magnetism; Melt spinning; Microstructure; Morphology; Permanent magnets; Rapid-solidification; Remanence; Transmission electron microscopy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.01.199

Alnico5 ribbons were prepared by melt spinning at 15 m/s and followed by annealing at 835 °C for 10 min and 580 °C for 4 h. The effects of magnetic field and annealing on the structure and magnetic properties of the ribbons were investigated. The results show that α1 and α2 phases display minor differences in elemental concentrations and the α1 phase presents an irregular morphology and inhomogeneous distribution when the ribbons are annealed without magnetic field. While a regular spinodal structure can be quickly formed after the ribbons are annealed only at 835 °C for 10 min under a magnetic field of 4 kOe, and a perfect spinodal structure consisting of about 60.9%–65.6% α1 and 34.4%–39.1% α2 finally builds up after further annealed at 580 °C for 4 h. The magnetic field plays an important role in promoting the diffusion of elements and accelerating the formation of spinodal structure, which leads to the remanence and maximum magnetic energy product increasing from 4.7 kGs and 1.25 MGOe to 8.8 kGs and 3.57 MGOe, respectively. And the microstructure evolution models are also presented. [Display omitted] •Alnico5 ribbons are prepared by melt spinning and annealing processes.•The phase transition of α-type phase at different states is analyzed.•The microstructure evolution models at different states are built up.•A regular spinodal structure can be quickly formed after annealed with magnetic field.•Applying magnetic field increases the maximum magnetic energy product by 185.6%.