Coercivity of Ti-modified (α-Fe)-Nd2Fe14B nanocrystalline alloys

Abstract
Coercivity of Ti‐modified nanocrystalline (α‐Fe)‐Nd2Fe14B alloys with soft iron particles embedded in hard Nd2Fe14B matrix was studied. The alloys were prepared by melt spinning and annealing. The grain size of Nd2Fe14B is from 20 to 60 nm, while that of the soft iron particles is 11 to 30 nm. The coercivity of the annealed flakes decreased dramatically with increasing particle size of free iron, following the same tendency of a theoretical calculation by Schrefl et al. For the Ti‐alloyed flakes, the 1 at. % Ti‐containing ones show the highest coercivity of 11.1 kOe. Its (BH)m value is about 16 MGOe despite lower Nd and B contents than stoichiometric Nd2Fe14B. More Ti addition would deteriorate the coercivity.