Magnetic and structural properties of the Nd2(Fe100−x Nb x )14B system prepared by arc melting

In this work the magnetic and structural properties are investigated by Mössbauer spectrometry, Vibrating Sample Magnetometry and X-ray diffraction of Nd₂(Fe_100?x Nb _x )₁₄B powdered alloys with x?=?0, 2 and 4 prepared by arc melting. The Mössbauer spectra of the samples were fitted with several contributions from: Nd₂Fe₁₄B, α-Fe and a paramagnetic phase associated with Nd_1.1Fe₄B₄ 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.