Synergetic crystallization in a Nd 2 Fe 14 B/α-Fe nanocomposite under electron beam exposure conditions

• Published in: Nanoscale Vol. 8; no. 42; pp. 18221 - 18227
• Main Authors: Tian, Haidong, Zhang, Yinfeng, Han, Jingzhi, Xu, Zhuang, Zhang, Xiaodong, Liu, Shunquan, Wang, Changsheng, Yang, Yingchang, Han, Li, Yang, Jinbo
• Format: Journal Article
• Language: English
• Published: England 27.10.2016
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/C6NR06884G

Nd Fe B/α-Fe nanocomposite magnets are prepared through electron beam exposure with a greatly reduced annealing time of 0.1 s. This is by far the most effective approach due to the effect of an extremely high heating rate featuring a rapid thermal process. The impact that the rapid thermal process has on crystallization is expounded by the introduction of the Landau model and Langevin dynamical simulations. The change of crystallization sequence from the α-Fe phase preceding the Nd Fe B phase under conventional annealing conditions, to synergetic crystallization under electron beam conditions is investigated. Synergetic crystallization results in more intense interaction between the α-Fe phase and the Nd Fe B phase in order to refine the microstructure as the fraction of Fe increases within our addition range. Improved uniformity, and shifts in the microstructure and distribution of the α-Fe phase contribute to the improvement of the magnetic properties. Compared with conventional furnace annealing ones, the magnetic properties of samples under electron beam exposure conditions are improved. For the Nd Fe B Nb Ga alloy, coercivity is enhanced from 4.56 kOe to 6.73 kOe, remanence ratio increases from 0.75 to 0.79, and a superior squareness of the hysteresis loop is achieved.