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1
Content available remote Effect of grain size and tungsten addition on microstructure and magnetic properties of Nd-Fe-B type magnets
Przybył A., Wnuk I., Gębara P., Wysłocki J. J.
Journal of Achievements in Materials and Manufacturing Engineering
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2011
|
Vol. 49, nr 2
210--214
EN
Purpose: The paper presents the results of the microstructural and magnetic examinations of Nd-Fe-B type magnets produced by the mechanical powder milling method and doped with tungsten. Design/methodology/approach: The effect of the grain size and addition of tungsten on the microstructure and magnetic properties of nanocrystalline alloys of the basic composition of Nd10Fe84B6, as produced by the method of mechanical alloying in the process of prolonged milling, was investigated in the study. Powders were subjected to milling for a duration ranging from 10 to 120 hours in an Ar protective atmosphere. Moreover tungsten was added to the base alloy that exhibited the best magnetic parameters. The tungsten content of alloys varied in a broad range from 0 to 33 at%. Findings: The examinations have shown that the grinding duration, for which the best magnetic properties are obtained, is 90 hours. Prolonged grinding has a significant effect on the grain size and microstructure refinement. The alloy addition in the form of tungsten, similarly as in the case of prolonged grinding, leads to a structure refinement. In the case of W addition, an increase in the coercive field, with a simultaneous decrease in the value of remanence and magnetic energy density (BH)max, is observed. Practical implications: Development of relatively cheap Nd10Fe84B6 magnets of good service properties. Originality/value: Determination of the effect of grain size and tungsten content on the magnetic properties and microstructure of the Nd-Fe-B magnets.
2
Stereologiczna metoda wyznaczania gęstości energii ścian domenowych wybranych jednoosiowych magnetyków
Przybył A., Pawlik P., Pawlik K., Wnuk I.
Hutnik, Wiadomości Hutnicze
|
2009
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Vol. 76, nr 5
351-354
PL
W pracy określono gęstość energii ścian domenowych w kilku grupach jednoosiowych ferromagnetyków: UFe10-xNixSi2 (x=0, 2, 4); UFe12-xAlxSi2 (x=1, 6); R2Fe14B (R=Pr, Nd, Gd, Dy); RMn2Ge2 (R=La, Ce, Pr, Nd) oraz Sm2Fe17N3, stosując stereologiczną metodę Bodenbergera-Huberta. Magnetyczną strukturę domenową obserwowano wykorzystując metodę figur proszkowych (ferrofluid). Ujawniona struktura domenowa jest typowa dla magnesów o jednym kierunku łatwego namagnesowania i dużej wartości anizotropii magnetokrystalicznej. Wyznaczone wartości gestości energii ścian domenowych porównano z wynikami literaturowymi otrzymanymi innymi metodami i stwierdzono dobrą zgodność.
EN
In the paper domain wall energy density for some groups of uniaxial magnetic materials: UFe10-xNixSi2 (x=0, 2, 4), UFe12-xAlxSi2 (x=1, 6), R2Fe14B (R=Pr, Nd, Gd, Dy), RMn2Ge2 (R=La, Ce, Pr, Nd) and Sm2Fe17N3, was determined applying stereologic method of Bodenberger and Hubert. Magnetic domain structure was observed using the powder pattern method (ferrofluid). The domain structure observed is typical for materials with one easy direction of magnetization. The values of domain wall energy density were compared with literature data determined using other methods and a good agreement was stated.
3
Content available remote Structure and magnetic properties of hot pressed powder Co77Si11.5B11.5 alloy
Konieczny J., Wnuk I., Dobrzański L.
Journal of Achievements in Materials and Manufacturing Engineering
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2008
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Vol. 31, nr 2
335-340
EN
Purpose: The aim of the work is to investigate the structure and magnetic properties of the cobalt based hot pressed Co77Si11.5B11.5 powder obtained in high-energy ball milling process. Design/methodology/approach: The nanocrystalline ferromagnetic powders were manufactured by highenergy ball milling (SPEX 8000 mill) of metallic glasses ribbons in as state. The hot pressing process was made on machine ''Degussa''. Observations of the structure of die stampings were made on the OPTON DSM-940 and ZEISS SUPRA 35 scanning electron microscope. Tests of magnetic properties were carried out by the use of Lake Shore's Vibrating Sample Magnetometer VSM model 7307. Findings: The analysis of the results enabled determination of the hot pressing parameters on magnetic properties and structure of obtained stampings. Research limitations/implications: For the metallic Co-based amorphous ribbons, further mechanical and structure examinations are planed. Practical implications: Structure and magnetic properties analysis of die stampings of powdered amorphous metallic ribbons is helpful to prepare this material by laboratory methods. Feature an alternative to commercial alloys and composite materials are the amorphous and nanocrystalline metal amorphous ribbons obtained by melt spinning technique and make it possible to obtain the new composite materials with best magnetic properties, which dimensions and shape can be freely formed. Originality/value: The paper presents influence of hot pressing parameters process of metallic powdered ribbons Co77Si11.5B11.5 on structure and magnetic properties of obtained die stampings.
4
Content available Phase structure of the nanocrystalline Nd2Fe14B/alfa-Fe magnets with different grain
Wnuk I., Wysłocki J., Przybył A.
Nukleonika
|
2007
|
Vol. 52, supl. 1
85-88
EN
The effect of the contents of the magnetically hard and magnetically soft phases on the magnetic properties of Nd2Fe14B + alfa-Fe nanocrystalline magnets, as produced by the method of mechanical alloying, has been established. The phase composition of specimens was determined using X-ray diffractometry and Mössbauer spectroscopy. The Mössbauer examination showed that as the powder milling times increased, the content of the Nd2Fe14B phase increased from 42.8% (after the milling time of 10 h, with a grain size of 44.8 nm) to 66.3% (after the milling time of 48 h, with a grain size of 37.3 nm) and then decreased to 40.3% after 120 h of milling. On the other hand, the content of the magnetically soft phase alfa-Fe initially decreased (from 27.7%), reaching a minimum after the milling time of 48 h (17.4%) and then increasing to 36.9% after 120 h of milling.
5
Content available remote Magnetic properties of hot pressed powder Co68Fe4Mo1Si13.5B13.5 alloy
Konieczny J., Dobrzański L. A., Wnuk I.
Journal of Achievements in Materials and Manufacturing Engineering
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2007
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Vol. 24, nr 2
111-114
EN
Purpose: The aim of the work is to investigate the structure and magnetic properties of the cobalt based hot pressed Co68Fe4Mo1Si13.5B13.5 powder obtained in high-energy ball milling process. Design/methodology/approach: The nanocrystalline ferromagnetic powders were manufactured by high-energy ball milling of metallic glasses ribbons in as state. The hot pressing process was made on machine "Degussa". Observations of the structure of die stampings were made on the OPTON DSM-940 scanning electron microscope. Graphical analyses of the obtained X-ray diffraction patterns, as well as of the HC=f(TA) relationship were made using the MICROCAL ORIGIN 6.0 program. Findings: The analysis of the magnetic properties and structure of the die stamping out that compared to the magnetic properties of the amorphous ribbons as their precursor, that hot pressing process deteriorates their magnetically soft properties. Research limitations/implications: For the metallic Co-based amorphous ribbons, further mechanical and structure examinations are planed. Practical implications: Structure and magnetic properties analysis of die stampings of powdered amorphous metallic ribbons is helpful to prepare this material by laboratory methods. Feature an alternative to commercial alloys and composite materials are the amorphous and nanocrystalline metal amorphous ribbons obtained by melt spinning technique and make it possible to obtain the new composite materials with best magnetic properties, which dimensions and shape can be freely formed. Originality/value: The paper presents influence of hot pressing parameters process of metallic powdered ribbons on structure and magnetic properties of obtained die stampings.
6
Microstructure and magnetic properties of nanocrystalline Nd2Fe14B/alpha-Fe magnets with different grain size.
Wnuk I., Wysłocki J. J., Przybył A., Kaszuwara W., Leonowicz M.
Archives of Materials Science
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2005
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Vol. 26, nr 4
263-277
EN
The nanocomposite Nd2Fe14B/alpha-Fe magnets with different grain size produced by mechanical alloying were studied. The phase composition of the magnets was determined on the basis of X-ray diffraction and Moessbauer spectroscopy. It was stated that the alloy is composed of three phases (with different volume fraction depending on the milling time): the magnetically hard phase Nd2Fe14B and the magnetically soft phases alpha-Fe and Nd2Fe17. In metallographic examinations, the techniques of optical, scanning and transmission electron microscopy were employed. Moreover, magnetic properties were determined depending on milling time (grain size). Maximum magnetic properties were achieved in the magnet produced from powders obtained after 90 hours' milling, which were as follows: Jr=0,914 T; jHc=251.1 kA/m; Js=2.12 T and (BH)max=67.7 kJ/cubic m.
7
Crystalline structure and magnetic properties of the Nd12.5-x Fe87.5 Zrx alloys (x = 2, 4, 6, 8, 10)
Pawlik K., Wysłocki J. J., Bodak O. I., Przybył A., Wnuk I.
Journal of Technical Physics
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2003
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Vol. 44, no 4
371-378
EN
The effect of Zr contents on the phase composition and magnetic properties of the Nd-Fe-Zr alloys was studied. In order to determine the phase composition, the X-ray diffraction was applied. It was stated that the following phases form the Nd-Fe-Zr alloy: Nd2Fe17, Fe3Zr and alpha-Fe. Using optical microscope and electron scanning microscope, the microstructure observations were performed. Additionally, a linear analysis of the distribution of elements concentration was carried out. Furthermore, magnetocrystalline anisotropy constants K\ and K-2 were determined applying Fourier analysis of the magnetic torque curves L(0) and Curie temperatures TC using Farady's magnetic balance
8
Rotational hysteresis energy in low-cobalt Fe-Cr-Co magnets
Wysłocki J. J., Wnuk I., Pawlik P.
Archiwum Nauki o Materiałach
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2001
|
T. 22, nr 3
169-177
EN
The mechanism of magnetization reversal processes in low-cobalt Fe-26.6 Cr-12.2 Co magnet has been investigated on the basis of the rotational hysteresis energy and its integral calculated from the magnetic torque curves. The results are compared with theoretical values obtained from Shtrikman-Treves theory. The modification of equation describing rotational hysteresis energy dependence on magnetic field Wr(H) has been introduced. It has been found that the magnetization reversal process occurs principally due to the curling mechanism. Moreover, magnetic domain structure observations are presented using the pattern method.
PL
Badano mechanizm przemagnesowania w magnesach o niskiej zawartości kobaltu 61,2 Fe-26,6 Cr-12,2 Co na podstawie strat z histerezy rotacyjnej Wr i całki z histerezy rotacyjnej R określonych z krzywych momentu skręcającego T. Otrzymane wyniki porównano z teoretycznymi wartościami wynikającymi z modelu Shtrikmana-Trevesa. Zaproponowano modyfikację równania opisującego zależność strat z histerezy rotacyjnej od przyłożonego pola magnetycznego Wr(H). Stwierdzono, że mechanizmem określającym proces przemagnesowania w magnesach Fe-Cr-Co jest curling (zawirowania). Ponadto, stosując metodę figur proszkowych (ferrofluid), ujawniono magnetyczną strukturę domenową w badanym magnesie Fe-Cr-Co.
9
Powierzchniowa struktura domenowa magnetycznie twardego stopu Fe-Cr-Co po różnych etapach obróbki cieplnej.
Wysłocki J. J., Pawlik P., Przybył A., Wnuk I.
Inżynieria Materiałowa
|
1999
|
R. XX, nr 5
538-541
PL
Stosując metodę figur proszkowych (ferrofluid) zbadano magnetyczną strukturę domenową stopu Fe-26,6Cr-12,2Co (% wag.) po różnych etapach obróbki cieplnej na powierzchniach ziarn równoległych i prostopadłych do kierunku magnetycznie wyróżnionego. Stwierdzono, że obserwowana struktura domenowa jest charakterystyczna dla materiałów o jednej osi łatwego magnesowania. W szczególności na płaszczyźnie równoległej do kierunku magnetycznie wyróżnionego obserwuje się 180 stopniowe ściany domenowe, natomiast na powierzchni prostopadłej występują domeny w kształcie mozaiki gwiazdek. Natomiast termomagnetyczna obróbka powoduje zmianę struktury domenowej o ścianach Blocha w strukturę domen wzajemnego oddziaływania. Domeny te tworzą ściany domenowe wzajemnie równoległe na płaszczyźnie aksjalnej i labiryntową strukturę na powierzchni bazalnej.
EN
Applying the powder pattern method (ferrofluid), magnetic domain structures of Fe-26,6Cr-12,2Co (wt. %) permanent magnet alloy at different stages of the heat treatment were studied on the grain surfaces parallel (axial plane) and perpendicular (basal plane) to the easy direction of magnetisation. The observed domain structures are typical for uniaxial materials. In particular, on the grain surfaces which are parallel to the magnetically preferred direction, domains with 180 degrees Bloch walls are apparent whereas on the perpendicular grain-surfaces, domains in the form of stars are visible. However, thermomagnetic treatment causes that doamins with Bloch's walls change into the interaction domains. These domains form the walls parallel to each other on the axial plane and labyrinth like structure on the basal plane.
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