scholarly journals Magnetic structure of Co–25%Sm sintered magnets after electrical discharge machining

2020 ◽  
pp. 59-67
Author(s):  
I. V. Slinkin ◽  
O. A. Chikova
Keyword(s):  
Grain Size ◽  
Chemical Composition ◽  
Magnetic Structure ◽  
Domain Structure ◽  
Electrical Discharge ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Electrical Discharge Machining ◽  
Force Microscopy ◽  
Defective Layer

Scanning electron microscopy and magnetic force microscopy were used to conduct the metallographic study of the surface microstructure of KS25 grade Co–25%Sm sintered rare-earth magnets after Electrical Discharge Machining (EDM). The chemical composition of the studied samples: Sm – 25 wt.%; Fe – 18 wt.%; Cu – 5 wt.%; Zr – 3 wt.%; Co – the rest. One of the sample surfaces was subjected to EDM in various ways with changes in such EDM parameters as the straight-line processing speed and offset. The microstructure of magnets contains four coexisting phases: SmCo5, Sm2Co17, Zr5Co3FeSm and Sm2O3. The grain size is 10–50 μm. Crystals of the Zr5Co3FeSm intermetallic compound are 1–5 μm in size, and globular inclusions of Sm2O3 samarium oxide are 2–10 μm. EDM affected the thickness and chemical composition of the defective layer. In general, the chemical composition varies slightly in the direction from the defective layer inward the sample: the content of Sm, Cu, O, and Zr decreases; the content of Fe and Co increases. At a distance of 500 μm from the defective layer inwards the sample, the grain size increases by 40–50 %, while the porosity decreases. At the same time, the size of Sm2O3 oxides slightly increases. The study of the magnetic structure on surfaces perpendicular to the axis of magnetization by means of magnetic force microscopy revealed the presence of a complex domain structure of grains in the form of a labyrinth with a domain size of ~3÷5 μm. Separate singledomain grains ~30÷50 μm in size were also found. Due to the material heating and oxidation, EDM promotes the domain structure of grains appearing in the form of a labyrinth instead of single-domain grains, and the SmCo5 → Sm2Co17 phase transition, which causes a decrease in coercive force.

scholarly journals Влияние текстуры на ширину доменов в спеченных магнитах (PrDy)(FeCo)B и (NdDy)(FeCo)B

2019 ◽  
Vol 61 (11) ◽  
pp. 2084
Author(s):  
А.И. Безверхний ◽  
О.В. Коплак ◽  
Р.А. Валеев ◽  
Д.В. Королев ◽  
В.П. Пискорский ◽  
...  
Keyword(s):  
Grain Size ◽  
Domain Structure ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Shear Plane ◽  
Projection Area ◽  
Easy Magnetization ◽  
Force Microscopy ◽  
Main Factors ◽  
Microscopy Images

AbstractWe analyzed magnetic force microscopy images of the surface of samples cut parallel and perpendicular to the texture created by applying a field in the process of pressing a magnet. The distribution of the linear size (width) of the domains correlates with the distribution of the projection area of grains onto the shear plane in sintered (PrDy)(FeCo)B magnets with radial magnetization and in prismatic (NdDy)(FeCo)B magnets. The effects of grain size and direction of the axes of easy magnetization of grains on the width of the domains, as the main factors controlling the domain structure, are discussed.

Magnetic force microscopy of combined reaction-processed polycrystalline equiatomic bulk L10 FePd

2009 ◽  
Vol 24 (8) ◽  
pp. 2677-2687 ◽  
Author(s):  
Paul R. Ohodnicki ◽  
Anirudha Desphande ◽  
Jorg M.K. Wiezorek ◽  
Timothy J. Klemmer
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Domain Structure ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Single Domain ◽  
Interaction Domain ◽  
Force Microscopy ◽  
Average Grain Size ◽  
Interaction Domains

In this work, the correlation between magnetic-domain structure and microstructure in combined reaction-processed equiatomic L10 FePd has been investigated using magnetic force microscopy. The microstructure consisted of approximately equiaxed grains with an average grain size of ∼1 μm and a grain size distribution ranging from below the theoretical critical domain size (Dcrit∼0.2–0.3 μm) up to approximately 5 μm in diameter. The domain structure was characterized as “mixed” in nature, consisting of smaller single-domain grains, larger multidomain grains, and a larger scale interaction domain structure encompassing many grains. The domain boundaries separating interaction domains tended to lie along grain boundaries, and it is proposed that the observed interaction domains should be considered in descriptions of the magnetization and magnetization reversal behavior of this material. In particular, pinning of interaction domain walls by intragranular features of the microstructure such as grain boundaries and single-domain grains could play a role in the measured coercivities.

scholarly journals Управление магнитной структурой CoNi-микрочастиц при помощи механических напряжений

2020 ◽  
Vol 62 (9) ◽  
pp. 1503
Author(s):  
Н.И. Нургазизов ◽  
Д.А. Бизяев ◽  
А.А. Бухараев ◽  
А.П. Чукланов
Keyword(s):  
Mechanical Stress ◽  
Magnetic Structure ◽  
Domain Structure ◽  
Glass Substrate ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Polished Glass ◽  
Homogeneous State ◽  
Force Microscopy ◽  
Elastic Bending

In work, the change of domain structure of CoNi microparticles caused by mechanical stress was studied. For this purpose, an array of identical square-shaped planar CoNi particles was formed on the surface of a polished glass substrate. Elastic bending of the substrate was used for creating of mechanical stress in the particles. It was shown by magnetic force microscopy, the magnetic structure of particles is possible to change from multidomain to quasi-homogeneous state by mechanical stress.

Domain structure of iron single crystals grown on Si(111) investigated by magnetic force microscopy (abstract)

1996 ◽  
Vol 79 (8) ◽  
pp. 6447 ◽  
Author(s):  
S. Foss ◽  
R. Proksch ◽  
K. Moloni ◽  
E. D. Dahlberg ◽  
Y. Cheng
Keyword(s):  
Single Crystals ◽  
Domain Structure ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Force Microscopy

The Domain Structure of Die-Upset Anisotropic Magnet Based On Nd-(Fe, Co)-B Alloy

2011 ◽  
Vol 56 (1) ◽  
pp. 159-161 ◽  
Author(s):  
D. Płusa ◽  
M. Dośpial ◽  
D. Derewnicka-Krawczyńska ◽  
P. Wieczorek ◽  
U. Kotlarczyk
Keyword(s):  
Domain Structure ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Magnetic Domain ◽  
Magnetic Interaction ◽  
Dipolar Interaction ◽  
Vibrating Sample Magnetometer ◽  
Force Microscopy ◽  
Interaction Domains ◽  
Anisotropic Magnet

The Domain Structure of Die-Upset Anisotropic Magnet Based On Nd-(Fe, Co)-B Alloy The measurements of the recoil curves for the die-upset Nd-(Fe, Co)-B based magnets from different points on the magnetization and demagnetization curves have been carried out by means of the LakeShore vibrating sample magnetometer in an applied magnetic fields up to 2 T. From the recoil curves the so-called Wohlfarth's remanence relationship has been derived. From this it was deduced that the magnetic interaction existing between the magnet grains has a dipolar nature. The existence of the magnetic interaction has been confirmed by magnetic domain observations by using the magnetic force microscopy (MFM). In the area of interaction domains there is the fine scale magnetic contrast resulting from the dipolar interaction between neighboring grains.

Effect of strain and growth morphology on the evolution of the domain structure of ferromagnetic manganites

2004 ◽  
Vol 819 ◽  
Author(s):  
Holly Miller ◽  
J. S. Higgins ◽  
Y. Mukovskii ◽  
R. L. Greene ◽  
Amlan Biswas
Keyword(s):  
Curie Temperature ◽  
Domain Structure ◽  
Strain Distribution ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Growth Morphology ◽  
Surface Magnetism ◽  
Two Phase ◽  
Force Microscopy ◽  
Magnetic Nanodots

AbstractThe effect of strain on the surface magnetism of the manganite La0.7Sr0.3MnO3 has been studied as a function of temperature, using magnetic force microscopy. The non- uniform strain distribution in the film leads to a two-phase coexistence between ferromagnetic and non-ferromagnetic phases. This leads to a reduction of the surface curie temperature and the formation of ferromagnetic islands. Methods of controlling this behavior in order to fabricate arrays of magnetic nanodots are discussed.

Plate domain structure of sintered NdFeB magnets and dependence on compacting mode

2001 ◽  
Vol 16 (10) ◽  
pp. 2992-2995 ◽  
Author(s):  
Zhen Rong Zhang ◽  
Bao Shan Han ◽  
Ye Qing He ◽  
Shou Zeng Zhou
Keyword(s):  
Domain Structure ◽  
Applied Field ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Magnetic Domain ◽  
Nonmagnetic Metal ◽  
Isostatic Pressing ◽  
Force Microscopy ◽  
Die Pressing ◽  
Better Than

The alignment degree of sintered Nd–Fe–B magnets and its dependence on applied field and compacting mode were studied by magnetic force microscopy. By analyzing the magnetic force images to illustrate the magnetic-domain structure, an experimental method for quantitatively evaluating the alignment degree of sintered Nd–Fe–B magnets was given. The results show that if the compacting mode is the same, the alignment of magnets will be better as field increases. Under the same field, the alignment degree for rubber isostatic pressing with vibration is better than that for nonmagnetic metal die pressing. However, if the sample is compacted by rubber isostatic pressing without vibration, the alignment degree decreases significantly.

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