Calorimetric study of Nd2Fe14B: Heat capacity, standard Gibbs energy of formation and magnetic entropy

Morishita, Masao; Abe, Taichi; Nozaki, Ai; Ohnuma, Ikuo; Kamon, Keisuke

doi:10.1016/j.tca.2020.178672

Cited by 9 publications

(16 citation statements)

References 65 publications

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“…Descriptions of the phases included in the database are given in Table 2 where the phases with "*" (B2-type, Dy 2 Fe 17 -type and Cu 5 Dy-type phases) are not yet unified because of the problem with sublattice configurations, which requires the Gibbs energy of metastable endmembers. reassessed and obtained a value of 0.8 from parameter fitting to the specific heat [87].…”

Section: Assessed Binary and Ternary Subsystemsmentioning

confidence: 99%

“…For the non-magnetic part of the heat capacity, Kopp-Neuman rule [43] was applied. A comparison between the measured [87,88] and calculated [56,83] heat capacities is presented in Fig. 2.…”

Section: Assessed Binary and Ternary Subsystemsmentioning

confidence: 99%

“…For expansion to higher-order systems, and to improve the descriptions of the Gibbs energy, the Gibbs energy functions adopted in the present work are based on the assessment of Hallemans et al In the previous assessments [ 56 , 82–86 ], there is one significant uncertainty, which is the Gibbs energy of the Nd 2 Fe 14 B phase because the heat capacity of the compound is not well characterized at high temperatures where the magnetic transition occurs. To improve on this uncertainty, Morishita et al [ 87 ] measured the heat capacity of Nd 2 Fe 14 B. According to their experimental results, it has a T C and the magnetic moment are 585.3 K and 2.04, respectively.…”

Section: Construction Of Database For Nd-based Magnetsmentioning

confidence: 99%

“…Thus, we adopted T C and f values from their measurements. Since the peak on the specific heat due to the magnetic transition becomes too high with 2.4 in Hallemans et al or 2.04 in Morishita et al, in the present work the thermodynamic magnetic moment, β , in Inden model was reassessed and obtained a value of 0.8 from parameter fitting to the specific heat [ 87 ]. For the non-magnetic part of the heat capacity, Kopp-Neuman rule [ 43 ] was applied.…”

Section: Construction Of Database For Nd-based Magnetsmentioning

confidence: 99%

“…Recently, Hanindriyo et al[86] reconsidered the stability of borides in the Bwell characterized at high temperatures where the magnetic transition occurs. To improve on this uncertainty, Morishita et al[87] measured the heat capacity of…”

mentioning

confidence: 99%

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Development of a prototype thermodynamic database for Nd-Fe-B permanent magnets

Abe

Morishita

Chen

et al. 2021

Science and Technology of Advanced Materials

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Development of a prototype thermodynamic database for Nd-Fe-B permanent magnetsFor the Nd-Fe-B permanent magnets, a prototype thermodynamic database of the 8-element system (Nd, Fe, B, Al, Co, Cu, Dy, Ga) was constructed based on literature data and assessed parameters in the present work. The magnetic excess Gibbs energy of the Nd 2 Fe 14 B compound was reassessed using thoroughly measured heat capacity data. The Dy-Nd binary system was reassessed based on formation energies estimated from ab initio calculations. The constructed database was applied successfully for estimations of phase equilibria during the grain boundary diffusion processes (GBDP) and the reactions in the hydrogenation decomposition desorption recombination (HDDR) processes.

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Section: Assessed Binary and Ternary Subsystemsmentioning

confidence: 99%

“…For the non-magnetic part of the heat capacity, Kopp-Neuman rule [43] was applied. A comparison between the measured [87,88] and calculated [56,83] heat capacities is presented in Fig. 2.…”

Section: Assessed Binary and Ternary Subsystemsmentioning

confidence: 99%

Section: Construction Of Database For Nd-based Magnetsmentioning

confidence: 99%

Section: Construction Of Database For Nd-based Magnetsmentioning

confidence: 99%

mentioning

confidence: 99%

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Development of a prototype thermodynamic database for Nd-Fe-B permanent magnets

Abe

Morishita

Chen

et al. 2021

Science and Technology of Advanced Materials

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Rare-Earths-Iron-Boron Compounds

Burzo

2023

Rare Earths-Transition Metals-Boron Compounds

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Investigation of the structural and magnetic properties of rapidly solidified Nd–Fe–B–Ce alloys

Aytekin,

Kurban,

Durmuş

et al. 2024

J Mater Sci: Mater Electron

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This study introduces the first literature report of rapidly solidified Nd–Fe–B–Ce alloys fabricated using the melt-spinning technique at varying disc rotation speeds. The resulting alloy images are then analyzed using various image processing techniques, and their structural and magnetic characteristics are described. The alloys are characterized using a variety of methods, including x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive x-ray spectroscopy (EDX), differential thermal analysis (DTA), vibrating sample magnetometry (VSM), and Vickers microhardness tests. By using XRD, the tetragonal hard magnetic Nd2Fe14B phase is detected in the Nd30Fe65B0.9Ce5 alloy. The FE-SEM microstructure analysis shows that the grain structure of the ingot alloy is indistinct, and the tetragonal symmetric structure begins to appear at disc rotation speeds of 20 m/s and 40 m/s. The analysis of FE-SEM images using histogram analysis, the image segmentation technique, and VSM method reveals that the coercivity values of the sample produced at the 80 m/s solidification speed increased by approximately 34% when compared to the ingot alloy.

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Calorimetric study of Nd2Fe14B: Heat capacity, standard Gibbs energy of formation and magnetic entropy

Cited by 9 publications

References 65 publications

Development of a prototype thermodynamic database for Nd-Fe-B permanent magnets

Development of a prototype thermodynamic database for Nd-Fe-B permanent magnets

Rare-Earths-Iron-Boron Compounds

Investigation of the structural and magnetic properties of rapidly solidified Nd–Fe–B–Ce alloys

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