Magnetic and structural properties of the Nd2(Fe100-xNbx)14B system prepared by arc melting

In this work the magnetic and structural properties are investigated by Moessbauer spectrometry, Vibrating Sample Magnetometry and X-ray diffraction of Nd2(Fe100-xNbx)14B powdered alloys with x = 0, 2 and 4 prepared by arc melting. The Moessbauer spectra of the samples were fitted with several contributions from: Nd2Fe14B, α-Fe and a paramagnetic phase associated with Nd1.1Fe4B4 for x = 0 and additionally from NbFeB and Nd2Fe17 for x = 2 and x = 4. The relative fractions of α-Fe and Nd2Fe14B are smaller for x = 4 than for x = 0, indicating that the amount of these two phases is reduced with increasing Nb content, while the relative fraction of Nd2Fe17 increases. The α-Fe grain size slightly decreases while that of the Nd2Fe14B phase is increasing, when the Nb content increases. The hysteresis loops indicate that these samples behave as hard ferromagnets, with a coercive field which decreases when the Nb content increases, but with rather low remanent magnetization.