Magnetic properties and phase evolution of melt spun R9.5Fe(bal.)Ti2B10 (R = MM(A), MM(B), MM(C), Pr, Nd, Ce, and La) nanocomposites have been investigated. Based on the results for the X-ray diffraction and thermal magnetic analysis, only 2:14:1 and alpha-Fe phases appear for R = MM(A) and Pr, and an additional Fe3B phase is present for R = MM(B), MM(C), Nd, and Ce. Besides, the uniform fine grain size of 20-40 nm is almost unchanged for the ribbons with various rare earth elements. Accordingly, magnetic properties of MM9.5Fe(bal.)Ti2B10 nanocomposites are mainly dominated by the composition of Mischmetals or the rare earth elements adopted, and are consistent with the outcome for the combinations of magnetic properties of their corresponding R9.5Fe(bal.)Ti2B10 nanocomposites. In this study, the optimum magnetic properties of B(r) = 9.3 kG, (i)H(c) = 12.1 kOe and (BH)(max) = 18.0 MGOe can be achieved for MM(B)9.5Fe(bal.)Ti2B10 nanocomposites. They not only exhibit comparable magnetic properties to the commercial available powders but also reduce the original material cost effectively.

Magnetic properties, phase evolution, and microstructure of melt spun Hf-substituted Sm(Co0.97Hf0.03)(x)Cy (x = 5-9; y = 0-0.1) ribbons quenched at the wheel speed of 40 m/s are investigated. X-ray diffraction analysis shows that the main phases existed in Sm(Co0.97Hf0.03)(x) ribbons are 1:5 phase for x = 5-5.5; 1:5 and 1:7 phases for x = 6; 1:7 phase for x = 6.5-7.5; 1:7 and 2:17 phases for x = 8; and only 2:17 phase for x = 8.5-9, respectively. For Sm(Co0.97Hf0.03)(x) (x = 5-9) ribbons, the optimum magnetic properties of B(r) = 5.6 kG, (i)H(c)= 15.6 kOe and (BH)(max) = 7.1 MGOe are obtained for Sm(Co0.97Hf0.03)6.5 ribbons. Furthermore, a slight amount of C addition in Sm(Co0.97Hf0.03)(x) ribbons slightly modify phase constitution and effectively refine the grain size from 200-700 nm for C free ribbons to 10-70 nm, strengthening the exchange coupling effect between magnetic grains of the ribbons. As a result, magnetic properties are further improved. The magnetic properties of B(r) = 6.9 kG, (i)H(c) = 9.2 kOe and (BH)(max) = 10.0 MGOe can be achieved for Sm(Co0.97Hf0.03)7.5C0.1 nanocomposites.

Effect of dopants on the soft magnetic properties and high frequency characteristics of FeCoBM thin films (M = Ti, Nb, Hf, and Ta) have been studied. For (Fe0.55Co0.45)(100-x)B(x) (x = 5-15) thin films, with the increase of B content, the resistivity was increased because B could decrease the crystallinity of the films. The (Fe0.55Co0.45)90B10 thin film showed the optimum properties, where 4piM(s) = 16.1 kG, H(ce) = 64.2 Oe, H(ch) = 13.5 Oe, H(k) = 310 Oe and p = 338 microomega-cm. To reduce the coercivity of the film, the elements M, including Ti, Nb, Hf, and Ta, were selected to substitute for B in the FeCoB films. It was found that (Fe0.55Co0.45)90B6Ti2Nb2 thin film after annealing at a temperature of 200 degrees C for 30 min showed the optimal properties, where 4piM(s) = 15.8 kG, H(ce) = 4.8 Oe, H(ch) = 3.6 Oe, H(k) = 224 Oe and p = 290 microomega-cm. The theoretically calculated ferromagnetic resonance frequency of the developed films can be higher than 5 GHz.