Enhancement in the coercivity in Nd2Fe14B/α-Fe nanocomposite alloys by Ti doping

Abstract

Nanocomposite α-Fe/Nd2Fe14B alloys with high coercivity were prepared by melt spinning. The influence of Ti addition on the microstructure and magnetic properties of these nanocomposite alloys were investigated. Ti addition has proved to result in relevant improvements in the microstructure and magnetic properties, especially in the coercivity Hc. It is shown that the magnetic properties of α-Fe/Nd2Fe14B nanocomposite are improved by an additional 5 at. % Ti, in particular, Hc from 595 up to 1006 kA/m, and (BH)max from 126.7 up to 135.3 kJ/m3. The coercivity mechanism of the α-Fe/Nd2Fe14B nanocomposite magnets was analyzed by studying the behavior of Hc(T)/Ms(T) versus HNmin(T)/Ms(T) (Kronmüller plot) and the dependence of Mirrev(H)/2Mr on the reverse field H. The results of this analysis show that nucleation is the dominating mechanism for the magnetization reversal in these nanocomposites. The Kronmüller plot gives evidence for a reduction in the exchange coupling resulting in an increase in the coercivity.