Nd(Fe,Mo)/sub 12/N/sub x/ compounds and magnets

Magnetic properties of Ce–Nd–Fe–Mo alloys and their nitrides

“…Based on our nitriding experiments, the combination of P ¼20 bar, t¼4 h, and T¼ 500 1C yielded the largest H ci and (BH) max , and hence was identified as the optimized condition and extended to the rest. It is worth noting that the hard magnetic properties of NdFe 10 Mo 2 nitrides obtained in this study are in excellent agreement with the values reported by Pinkerton et al [12] and Endoh et al [9] in Nd-Fe-Mo nitrides of comparable compositions. Larger H ci values could be obtained by nitriding Ndrich precursors prepared by mechanical alloying [9,10,14,15,23].…”

“…After nitriding, however, samples containing Nd exhibit greatly enhanced H ci values. For NdFe 12 À y Mo y nitrides, H ci increases with increasing y, but the difference between y¼1.5 and 2 is much smaller compared to that between y¼1.5 and 1, which is in good agreement with the finding by Endoh et al [9,10]. For fixed Mo content y, H ci in Ce 1 À x Nd x Fe 12 À y Mo y N z follows a nearly linear dependence on Nd content x.…”

“…Using magnetically hardened melt spun ribbons, Pinkerton et al have achieved H ci ¼ 5.5 kOe in Nd 1.15 Fe 10 Mo 2 after nitriding for 64 h [12]. H ci values varying from 3.0 to 13.1 kOe have also been reported in Nd-Fe-Mo alloys by other groups from nitriding arc melted, mechanical alloyed, or strip cast materials [9,11,[13][14][15]. Theoretical work indicates that the dramatic increase of H a in NdFe 12 À x M x alloys is due to the change of second-order crystal field coefficient A 20 from small and negative to large and positive by the insertion of the nitrogen atom [16,17].…”

“…In addition to the much improved T c and 4πM s , NdFe 12 À x M x exhibits a strong uniaxial anisotropy field H a and high coercivity H ci after nitriding. For instance, Anagnostou et al [6,7], Chen et al [8], Endoh et al [9,10], and Wang et al [11] have independently demonstrated H a of 68-78 kOe in NdFe 10 Mo 2 N x at room temperature, a value that is comparable to that of the state-of-the-art permanent magnet compound Nd 2 Fe 14 B. Using magnetically hardened melt spun ribbons, Pinkerton et al have achieved H ci ¼ 5.5 kOe in Nd 1.15 Fe 10 Mo 2 after nitriding for 64 h [12].…”

Investigation of structural stability and site preference of Dy(Fe,T)12 and Dy(Fe,T)12Nx (T=Ti, V, Cr, Nb, Mo)

“…The nitrogen atoms in NdFe 10 V 2 N x were verified to occupy the 2b sites as in the case of RFe 11 TiN x [13]. A moderate coercivity has been obtained in the Nd(Fe,V) 12 [14,15]. Accordingly it is interesting to do a systematic study on the R(Fe,T) 12 N x .…”