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The substitution of V for Zr significantly impeded the growth of grain in the Co82Zr18 ribbons during melt spinning and the amorphous Co82Zr13V5 melt-spun ribbons were successfully produced at a wheel speed of 40m/s. The values of coercivity H c and maximum energy product (BH) max first increased, reaching maximum at 560°C and then they decreased sharply with increasing the annealing temperature. The optimal magnetic properties of H c =4.0kOe and (BH) max =5.0MGOe were obtained in the amorphous ribbons annealed at 560°C. A suitable grain size of Co11Zr2 phase was considered to be the main reason for the increase in coercivity. [ABSTRACT FROM AUTHOR]

Nd 2 Fe 14 C-based magnet is prepared by a mechanochemical method, namely high-energy ball-milling Nd 2 Fe 11 B x (x = 0–0.15) alloy in heptane (C 7 H 16 ), followed by annealing to 850 °C in vacuum. Under the action of high-energy ball-milling, Nd 2 Fe 11 B x react with heptane to form NdH 2+δ , Fe-(CB), C, etc. H 2 is released and Nd 2 Fe 17 , Nd 2 Fe 17 C x (x = 0–3), Nd 2 Fe 14 C, Nd carbides and α-Fe are formed in the subsequent annealing. C amount depends on ball-milling time t . Long time ball milling or high C content suppresses the formation of 2:17 phase and favors the formation of 2:14:1 phase in the final products. Excessive ball-milling results in the quick increase of α-Fe. The maximum of magnetically hard Nd 2 Fe 14 C is obtained at t = 4 h. For Nd 2 Fe 11 samples, there exists considerable quantity of Nd carbides and α-Fe phase appears earlier and increases rapidly with extending the ball-milling time t . The addition of B element shortens the ball-milling time of the formation of maximum Nd 2 Fe 14 C and prominently suppresses the formation of Nd carbide and α-Fe. The optimum magnetic properties, coercivity i H c of 1193.7 kA/m, remanence M r of 580.9 kA/m, maximum magnetic energy product ( BH ) max of 91.7 kJ/m 3 is approaching to its theoretic value of 99.2 kJ/m 3 for isotropic Nd 2 Fe 14 C magnet, are obtained in Nd 2 Fe 11 B 0.06 alloy ball milled for 3.5 h. [ABSTRACT FROM AUTHOR]

Abstract: The phases, microstructure, and magnetic properties of Co80Zr18−x Nb x B2 (x=1, 2, 3, and 4) melt-spun ribbons were investigated. The small substitution of Nb for Zr in the Co–Zr–B melt-spun ribbons resulted in the improvement of magnetic properties, especially the coercivity. The main effect of added Nb on the coercovity of Co–Zr–Nb–B melt-spun ribbons, originated from modification of the grain size of Co11Zr2 phase. The coercivity of the Co–Zr–Nb–B melt-spun ribbons depends on the annealing temperature. The optimal magnetic properties of H c =5.1kOe, and (BH) max =3.4MGOe were obtained in the Co80Zr15Nb3B2 melt-spun ribbons annealed at 600°C for 3min. [Copyright &y& Elsevier]

• Nano-sized Pr 2 Fe 14 C-based magnetic particles were prepared by a facile mechanochemical method. • H 2 and C were introduced by the decomposition of heptane during the high-energy ball milling process. • The two-step recombination reaction during the annealing process was discovered and discussed. • The addition of boron promoted the formation of Pr 2 Fe 14 C phase and suppressed soft magnetic products. A facile mechanochemical method for fabricating Pr 2 Fe 14 C-based magnetic nanoparticles was reported. H and C were introduced by the decomposition of heptane during the high-energy ball milling process and reacted simultaneously with Pr 3 Fe 14 B x (X = 0–0.2) alloy to form Fe 7 C 3 , PrH 2+δ and α-Fe phases. Subsequently, the H 2 released from the PrH 2+δ and Pr 2 Fe 14 C-based magnetic materials were obtained during a fast vacuum annealing process. Compared with the traditional heat-treatment which involved time-consuming annealing and multi-steps cooling process, the zero holding time annealing with a fast heating rate will effectively reduce the energy consumption. Addition of small amounts of boron is demonstrated to promote the formation of Pr 2 Fe 14 C and reduce the quantity of magnetically soft Pr 2 Fe 17 and α-Fe phases. The optimal magnetic properties of M r = 5.9 kG, i H c = 19.8 kOe and (BH) max = 8.0 MGOe were obtained in Pr 3 Fe 14 B 0.1 sample after ball-milling for 7 h and subsequently annealing. Microstructure morphology analysis of the as-annealed Pr 3 Fe 14 B 0.1 powder reveals that the particles are almost rectangular shapes with an average size of about 117 nm. This bottom-up approach for fabrication of Pr 2 Fe 14 C nanoparticles may provide new thoughts for the preparation of high-performance magnetic materials. [ABSTRACT FROM AUTHOR]