A study of Pr-Fe-B magnets produced by a low-cost powder method and the hydrogen decrepitation process

Soares, Edson Pereira; Périgo, E.A.; Takiishi, Hidetoshi; Motta, C.C.; Faria, Rubens Nunes de

doi:10.1590/s1516-14392005000200008

Cited by 4 publications

(3 citation statements)

References 9 publications

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“…The amount of molybdenum (38.4 mol%) was chosen based on the Ni-Mo phase diagram, and the grind was performed during 48 hours in anhydrous ethanol to minimize the oxidation reaction 8,9 .…”

Section: Powder Homogenization and Millingmentioning

confidence: 99%

Synthesis and characterization of Ni-Mo filler brazing alloy for Mo-W joining for microwave tube technology

Sene

Motta

2013

Mat. Res.

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A brazing process based on Ni-Mo alloy was developed to join porous tungsten cathode bottom and dense molybdenum cathode body for microwave tubes manufacture. The Ni-Mo alloy was obtained by mixing and milling powders in the eutectic composition, and applied on the surface of the components. The brazing was made at 1400 °C by using induction heating in hydrogen for 5 minutes. Alumina surfaces were coated with the binder and analyzed by Energy Dispersive X-rays Fluorescence. The brazed samples were analyzed by Scanning Electron Microscopy coupled to Energy Dispersive Spectroscopy. Stress-strain tests were performed to determine the mechanical behavior of the joining. The quality of the brazing was evaluated by assuring the presence of a "meniscus" formed by the Ni-Mo alloy on the border of the tungsten and molybdenum joint, the absence of microstructural defects in the interface between the tungsten and molybdenum alloys, and the adhesion of the brazed components.

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“…The amount of molybdenum (38.4 mol%) was chosen based on the Ni-Mo phase diagram, and the grind was performed during 48 hours in anhydrous ethanol to minimize the oxidation reaction 8,9 .…”

Section: Powder Homogenization and Millingmentioning

confidence: 99%

Synthesis and characterization of Ni-Mo filler brazing alloy for Mo-W joining for microwave tube technology

Sene

Motta

2013

Mat. Res.

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“…In order to assess its results, the most common type of hard magnets rareearth-based were explored to clarify correlations between (micro)structural characteristics, analogous electric parameters, and magnetic properties. For the case of rare-earth PMs, Pr 16 Fe 76 B 8 sintered permanent magnets with optimized processing conditions according to [23,24] were used. The hysteresis shape quantification was determined using H k /H cj definition [12,13].…”

Section: Methodsmentioning

confidence: 99%

Modelling and simulation of electrical analogous for permanent magnet materials

Fernandez,

Perigo,

de Faria Junior

2023

Phys. Scr.

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Expressions to simulate the intrinsic demagnetizing curve of permanent magnets are derived from the classical electrical analogy of a 2RLC circuit as an equivalent to a magnet under demagnetization in a closed magnetic circuit. Comparisons between experimental and theoretical intrinsic M x H curves were carried out for hard magnetic materials, and the possibility of using this analogous circuit with two components has also been investigated. The Stoner-Wohlfarth model theoretical curves have also been used as a comparison. At last, the electrical analogous parameters have been systematically varied in order to correlate them to the magnetic properties.

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“…It is possible to identify at least seven steps: melting of the alloy, homogenization, milling, powder magnetic alignment and compaction, sintering and post-sintering heat treatment. Good HD sintered REFeB magnets have been produced using the "roller" ball milling (RBM) from alloys comminuted between 64.8 and 72.0 ks (18 and 20 hours, respectively) 2,3 . However, milling is time consuming, even using the hydrogen decrepitation (HD) process.…”

Section: Introductionmentioning

confidence: 99%

A study of high-energy milling for the production of sintered PrFeB magnets

et al. 2007

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Sintered Pr16Fe76B8 magnets have been produced using the hydrogen decrepitation (HD) process and high-energy planetary ball milling. Investigations have been carried out to evaluate the influence of the milling speed and time. The best magnetic properties obtained were Br = (1020 ± 20) mT, µ0iHc = (1420 ± 30) mT and (BH)max/= (200 ± 4) kJm-3, for a magnet prepared with the alloy milled at 200 rpm for 4.5 ks. Magnets prepared from this powder exhibited a superior intrinsic coercivity compared to that of magnets produced using low-energy ball milling. However, the remanence and energy product of the latter were somewhat lower. An important feature was the dramatic reduction in the processing time (about 90%). Microstructural observation have shown that increasing the milling time and keeping constant the rotational mill speed caused an exponential grain size reduction in the sintered magnet. Increasing the milling speed also reduced the grain size and influenced both remanence and intrinsic coercivity

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A study of Pr-Fe-B magnets produced by a low-cost powder method and the hydrogen decrepitation process

Cited by 4 publications

References 9 publications

Synthesis and characterization of Ni-Mo filler brazing alloy for Mo-W joining for microwave tube technology

Synthesis and characterization of Ni-Mo filler brazing alloy for Mo-W joining for microwave tube technology

Modelling and simulation of electrical analogous for permanent magnet materials

A study of high-energy milling for the production of sintered PrFeB magnets

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