The crystallization behavior of as-quenched Nd 9 Fe 85 Nb 0.5 B 5.5  alloys

Men, Kuo; Li, Kuoshe; Luo, Yang; Yu, Dunji; Zhang, Kun; Jin, Jinling; Mao, Yongjun

doi:10.1016/j.jallcom.2015.02.046

Cited by 9 publications

(2 citation statements)

References 20 publications

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“…Our previous studies had proved that the crystallization process of the as-quenched alloys prepared at a wheel speed of 24 m/s was divided into two steps: 13 The TbCu 7 -type metastable phase (Nd 2 Fe 17 B x phase) together with a small amount of α-Fe precipitated from the matrix; then the precipitated Nd 2 Fe 17 B x phase was decomposed into α-Fe and Nd 2 Fe 14 B phase. While in this study, the crystallization process could be regarded as three phases precipitating from the matrix successively.…”

Section: Resultsmentioning

confidence: 99%

Effect of wheel speed on the crystallization behavior of as-quenched Nd-Fe-B alloys

Men

Luo

et al. 2016

AIP Advances

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A series of alloys composed of Nd9Fe85Nb0.5B5.5 were prepared through rapid quenching by different wheel speeds. Nanocomposite was usually obtained by subjecting the as-quenched alloys to a crystallization annealing. The crystallization behavior was investigated by differential scanning calorimetry (DSC) as the primary method. The results showed that the DSC curve of sample prepared at 15 m/s had only one exothermic peak at about 690 °C. When the wheel speed increased to 18-27 m/s, one more peak at 590 °C appeared. Moreover, the intensity of this new peak enhances while the original one at 690 °C declined as the speed increases within this range. When the speed further grew up to 30, 35, or 40 m/s , only the peak at 590 °C remained while the other disappeared. This could be ascribed to the different initial phase structures of the alloys, which were found to vary with the wheel speeds. As can be seen, with increasing the wheel speed, the contents of amorphous and metastable phase increased while Nd2Fe14B phase decreased. This change resulted in a huge effect on the crystallization behavior. We could deduce the relative content of each phase from the integral areas of peaks in DSC curves in different samples and figure out the phase transition in the crystallization. The results showed that the crystallization of samples prepared by relatively high speeds, which are almost amorphous initially, manifest as only one step, while those prepared by relatively low speeds showed two. Subsequently, we analyzed the crystallization process and interpreted it from the theory of energy barrier.

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Section: Resultsmentioning

confidence: 99%

Effect of wheel speed on the crystallization behavior of as-quenched Nd-Fe-B alloys

Men

Luo

et al. 2016

AIP Advances

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“…Much of the research has been focused on amorphous samples where different fabrication methods (melt-spinning, mechanical alloying) and annealing treatments were investigated to obtain the best properties. The type and amount of different amorphous/disordered phases obtained by meltspinning can be controlled using different wheel speeds [7] and can be well tuned by small substitutions of Nb [8,9] avoiding any secondary heat treatment. However, this results in a high structural inhomogeneity when compared with the heat-treated samples.…”

Section: Introductionmentioning

confidence: 99%

Effect of Nb and Cu on the crystallization behavior of under-stoichiometric Nd–Fe–B alloys

Salazar¹,

Martín-Cid²,

Madugundo³

et al. 2016

J. Phys. D: Appl. Phys.

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In this work, we present a complete study of the influence of Nb and Cu addition on the crystallization behavior of Nd-lean Nd-Fe-B melt-spun alloys. Alloys with compositions Nd 10−x−y Fe 84 B 6 Nb x Cu y (x = 1, y = 0 and x = 0.5, y = 0.5) were melt-spun at different wheel speeds (15-40 m s −1) to obtain samples in amorphous, highly disordered and nanocrystalline structures. The crystallization process, induced by different heat treatments, was studied by means of differential thermal analysis and x-ray powder thermodiffraction. Magnetic properties of as-made and heat-treated ribbons were measured by magnetometry. The as-made amorphous samples showed a crystallization to the 2:14:1 hard magnetic phase at T 1 ~ 350 °C. Doping with Nb results in an increase of T 1 , and addition of Cu lowers T 1. This behavior is explained in terms of an inhibition of grain growth by Nb and a nucleation enhancement by Cu additions. During the crystallization process, a secondary phase (identified as a bcc-Fe-rich phase) is formed. The amount of such a phase increases with the annealing temperature. Coercivity increases upon annealing reaching maxima at 700-750 °C. This can be explained in terms of competition between the two phases formed: the 2:14:1 hard phase and the soft bcc-Fe-rich phase. The highest coercivity of the Nd-lean samples is observed when the microstructure is appropriate and both phases are exchange-coupled.

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Influence of Cu Content on Crystallization Kinetics and Microstructure of Nd-Fe-B Thick Ribbons

Dong¹,

Yang

Chen³

et al. 2017

J Supercond Nov Magn

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The crystallization behavior of as-quenched Nd 9 Fe 85 Nb 0.5 B 5.5 alloys

Cited by 9 publications

References 20 publications

Effect of wheel speed on the crystallization behavior of as-quenched Nd-Fe-B alloys

Effect of wheel speed on the crystallization behavior of as-quenched Nd-Fe-B alloys

Effect of Nb and Cu on the crystallization behavior of under-stoichiometric Nd–Fe–B alloys

Influence of Cu Content on Crystallization Kinetics and Microstructure of Nd-Fe-B Thick Ribbons

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