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1

The influence of pulsating tensile stress on residual magnetic field of P91 steel samples

Złocki A., Roskosz M., Kwaśniewski J.

Advances in Materials Science

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2019

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Vol. 19, nr 2(60)

72--82

EN

Measurements of Residual Magnetic Field RMF (the tangential component parallel to the load direction) were taken on the surface of P91 steel plate samples (X10CrMoVNb9-1) subjected to periodic pulsating tensile cyclic loads with the use of flux-gate and magnetoimpedance sensors, and preliminary measurement results are compiled and analyzed. The study investigates how the microstructure and load cycle parameters affect the RMF changes due to stress variations. Each combination of parameters: microstructure and load cycle corresponds to the characteristic variability pattern of magnetization and its maximum and minimum values.

2

Magnetotransport and magnetic properties of manganites doped with iron and aluminum

Troyanchuk I., Bushinsky M., Tereshko N., Fedotova V.

Zeszyty Naukowe Wydziału Elektroniki i Informatyki Politechniki Koszalińskiej

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2017

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Nr 11

5--10

EN

The single crystals of La0.7Ba0.3(Mn1-xFex)O3 (x ≤ 0.28) and La0.7Ba0.3(Mn1-xAlx)O3 (x ≤ 0.15) compositions were grown using flux method and characterized by X-ray, electrical and magnetization measurements. The replacement of Mn ions by Al ions in the La0.7Ba0.3Mn1-xAlxO3 system leads to a decrease in the temperature to 311 K for the sample x=0.1. The Fe-doping above x=0.2 destroys a long range ferromagnetic order thus leading to a spin glass state. It is found that insulating spin glasses exhibit a large magnetoresistance in the paramagnetic region that is comparable to that for ferromagnetic crystals showing metal–insulator transition near TC.

PL

Monokryształy La0,7Ba0,3(Mn1-xFex)O3 (x ≤ 0,28) i La 0,7Ba 0,3 (Mn1-xAlx)O3 (x ≤ 0,15) wyhodowano metodą strumieniową i charakteryzowano poprzez badania rentgenowskie, pomiary elektryczne i magnetyzacyjne. Zastąpienie jonów Mn jonami Al w układzie La0,7Ba0,3Mn1-xAlxO3 prowadzi do obniżenia temperatury do 311 K dla próbki x = 0,1. Domieszka Fe powyżej x = 0,2 niszczy ferromagnetyczny porządek dalekiego zasięgu atomów Fe, prowadząc w ten sposób do spinowego stanu typu szkła. Stwierdzono, że izolacyjny spinowy stan typu szkła wykazuje dużą rezystancję magnetyczną w obszarze paramagnetycznym, która jest porównywalna z kryształami ferromagnetycznymi i wykazują przejście metal-izolator w pobliżu TC.

3

Właściwości magnetyczne i mikrostruktura kompozytów wytworzonych na bazie amorficznego stopu Fe60Co10Y8Zr1B20 spajanego żywicą epoksydową

Nabiałek M.

Przetwórstwo Tworzyw

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2014

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[R.] 20, nr 1 (157)

56--61

PL

W pracy przedstawiono wyniki badań kompozytów wykonanych na bazie stopu amorficznego o składzie chemicznym Fe60Co10Y8Zr1B20 i żywicy epoksydowej. Badane próbki miały kształt walców o takich samych wymiarach i takiej samej zawartości Epidianu 100. Amorficzny stop objętościowy został niskoenergetycznie rozkruszony i rozdzielony na trzy frakcje: 20 - 50 μm, 50 - 100 μm i 100 - 200 μm a następnie zespolony przy użyciu Epidianu 100. W wyniku przeprowadzonych badań mikrostruktury stwierdzono, że kompozyt na bazie metalicznego stopu jest amorficzny. Stwierdzono również, że rozwinięcie powierzchni dla kompozytu złożonego z metalicznych drobin o frakcji 20 - 50 μm było najmniejsze. Mikrotwardość badanych próbek, niezależnie od wielkości metalicznych drobin była porównywalna. Na podstawie analizy badań magnetyzacji w funkcji natężenia pola magnetycznego wykazano, że wartość pola koercji dla badanych kompozytów rośnie wraz z rozkładem wielkości cząstek metalicznych. Pokazano również, że wielkość frakcji ma znikomy wpływ na wartość magnetyzacji nasycenia.

EN

The paper presents the studies of composites, made from amorphous alloy particles with the chemical composition of Fe60Co10Y8Zr1B20 and epoxy resin. The investigated samples had cylindrical shapes of the same size and contained the same weight content of Epidian 100. The volumetric amorphous alloy was low energy-grinded and separated into three fractions: 20 - 50 μm, 50 - 100 μm and 100 - 200 μm. According to the microstructure studies, it was found that the metal-based alloy is amorphous. It was also found, that the development of the surface of the composite, made up of particles of metallic fraction of 20 - 50 microns, was the lowest. The microhardness of the studied samples, regardless of the size of the metallic particles, was comparable. Based on the analysis of the studies of magnetization as a function of magnetic field strength it was shown that the coercivity field value for the analyzed composites increases with increasing fractions of the metal particles. It was also shown that the fraction size has little effect on the value of the saturation magnetization.

4

Matematyczny model pętli histerezy magnetycznej

Sztymelski K., Pasko M.

Prace Naukowe Politechniki Śląskiej. Elektryka

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2014

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z. 1

81--88

PL

W artykule został zaprezentowany matematyczny model pętli histerezy magnetycznej. Zostały wyprowadzone równania matematyczne opisujące pętlę, wykorzystujące funkcje parametryczne oraz funkcje B = f(H). Uzyskane wyniki zilustrowano przykładami, w tym również aproksymacją charakterystyki magnesowania badanej próbki rzeczywistej.

EN

In this article the mathematical model of B-H loop has been presented. The formulae describing the B-H loop using the parametric functions and functions B = f(H) have been carried out. Obtained results have been illustrated by an examples including the approximation of B-H loop of real material sample.

5

The influence of resin content on the mechanical and soft magnetic properties of composite prepared on the basis of the bulk amorphous materials

Błoch K., Nabiałek M., Szota M.

Inżynieria Materiałowa

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2014

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Vol. 35, nr 2

82--85

EN

The paper presents studies of microstructure, magnetic and mechanical properties of composite prepared on the basis of the bulk amorphous materials. The results presented in this work indicate, that it is possible to generate electrotechnical composite material having a rather high microhardness, which are built in more than 95 wt % of amorphous ferromagnetic metal powder, and the remaining part is Epidian 100 resin. Examined composites were fully amorphous and homogeneous. The homogeneity of the material from which ferromagnetic particles are prepared for composites is an important parameter, which ensures the same properties throughout the entire volume of the composite. Combination of amorphous particles of fraction 100÷200 microns, with the polymeric binder, resulted in a microhardness reduction in relative to the bulk amorphous plate. With increasing weight content of the resin, in the composite, the saturation magnetization significantly decreased, while the coercivity field increased over twentyfold.

PL

W pracy przedstawiono wyniki badań struktury, właściwości magnetycznych i mechanicznych przeprowadzonych dla kompozytów wytworzonych z amorficznych cząstek połączonych żywicą epoksydową. Otrzymane wyniki wskazują, że jest możliwość wytworzenia elektrotechnicznego materiału kompozytowego o dość dużej mikrotwardości zbudowanego w ponad 95% z ferromagnetycznego metalicznego amorficznego proszku, resztę stanowi żywica epidian 100. Badane materiały kompozytowe były w pełni amorficzne i homogeniczne, co oznacza, że rozdrobniony materiał uzyskany z amorficznych płytek miał dobrą jednorodność. Jednorodność materiału, z którego wytwarza się cząstki ferromagnetyczne dla kompozytów jest istotnym parametrem, zapewniającym zachowanie takich samych właściwości w całej objętości kompozytu. Zespolenie amorficznych cząstek o frakcji 100÷200 μm polimerowym lepiszczem wpłynęło na obniżenie mikrotwardości w porównaniu z próbką w postaci płytki. Wraz ze wzrostem zawartości żywicy w kompozycie znacznie zmniejszyła się magnetyzacja nasycenia, natomiast pole koercji wzrosło ponad dwudziestokrotnie.

6

Peculiarities of conductivity, structure and magnetization of oxidized FeCoZr-Al2O3 granular nanocomposites

Kasiuk J., Fedotova J., Svito I., Akimov A., Kołtunowicz T., Węgierek P.

Przegląd Elektrotechniczny

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2010

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R. 86, nr 7

134-135

EN

(FeCoZr)x(Al2O3)100-x composites have been obtained with ion-beam sputtering in atmosphere Ar and O. Mössbauer spectroscopy, inductive magnetometry and conductivity measurements were carried out for investigation of nanocomposites structure and properties. Performed investigation revealed the opportunity to influence by hydrogenation on FeCoZr-Al2O3 structure and magnetic properties.

PL

Kompozyty (FeCoZr)x(Al2O3)100-x były uzyskane przez rozpylanie jonowe w atmosferze Ar i O. Przeprowadzono pomiary konduktywności oraz badania struktury i właściwości nanokompozytów przy użyciu spektroskopii Mössbauerowskiej i magnetometrii indukcyjnej. Przeprowadzono badania wykazują pływ hydrogenizacji na strukturę i właściwości magnetyczne FeCoZr-Al2O3.

7

Magnetic properties of nanocomposites (CoFeZr)x(Al2O3)1-x

Zhukowski P., Sidorenko J., Kołtunowicz T., Fedotova J., Larkin A.

Przegląd Elektrotechniczny

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2010

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R. 86, nr 7

296-298

EN

The results of the ESR study of nanocomposite films, prepared by sputtering of complex alloy target by Ar ions, are presented. Strong angular dependences of maximum H max and minimum H min positions in ESR lines and also g-factor were revealed. ESR measurements allowed to determine magnetization values in the (CoFeZr)x(Al2O3)1-x samples with metallic phase concentration x from 31 at.% to 47 at.%. It was ascertained that growth of metallic phase particles in the film bulk occurs due to diffusion of metallic atoms, defragmented in dielectric matrix during the sputtering procedure, under isochronous (15 min over 25°?) annealing of the samples at 400oC.

PL

W artykule omówiono wyniki badań metodą elektronowego rezonansu paramagnetycznego nanokompozytów (CoFeZr)x(Al2O3)1-x wytworzonych rozpylaniem magnetronowym tarcz ze stopu i dielektryka jonami Ar+. Zaobserwowano zależności kątowe położenia maksimum linii H max, minimum linii H min, szerokości linii [delta]H i wartości czynnika g. Określono wartości namagnesowania dla próbek z koncentracjami fazy metalicznej x od 31% do 47%. Ustalono, że podczas wygrzewania próbek w temperaturach do 400°? zachodzi dyfuzja atomów metali z fazy dielektrycznej i wzrost objętości fazy metalicznej. W artykule omowiono wyniki bada. metod. elektronowego rezonansu paramagnetycznego nanokompozytow (CoFeZr)x(Al2O3)1-x wytworzonych rozpylaniem magnetronowym tarcz ze stopu „R„€0,45F„u0,45Zr0,1 i dielektryka „@l2„O3 jonami „@r+. Zaobserwowano zale.no.ci k.towe po.o.enia maksimum linii „Nmax, minimum linii „Nmin, szeroko.ci linii �˘„N i warto.ci czynnika g. Okre.lono warto.ci namagnesowania dla probek z koncentracjami fazy metalicznej x od 31% do 47%. Ustalono, .e podczas wygrzewania probek w temperaturach do 400�‹„R zachodzi dyfuzja atomow metali z fazy dielektrycznej i wzrost obj.to.ci fazy metalicznej.

8

Effect of presence of dust particles on soret-driven ferrothermohaline convection

Sekar R., Vaidyanathan G., Hemalatha R.

International Journal of Applied Mechanics and Engineering

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2009

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Vol. 14, no 2

509-522

EN

Soret driven thermoconvective instability in multicomponent fluids has wide applications in heat and mass transfer. This paper deals with the theoretical investigation of the effect of dust particles on Soret-driven thermohaline convection in a ferrofluid, heated and soluted from below subjected to a transverse uniform magnetic field. An exact solution is obtained for the case of two free boundaries. A linear stability analysis is used. A normal mode technique is applied. Both stationary and oscillatory instabilities are investigated. It is found that the system stabilizes through stationary mode. The non-buoyancy magnetization parameter and the dust particle parameter are found to destabilize the system. The Soret coefficient and the stable solute gradient tend to stabilize the system. The results are presented graphically.

9

Soret-driven thermohaline convection in dusty ferrofluids saturating a porous medium

Sekar R., Vaidyanathan G., Hemalatha R.

International Journal of Applied Mechanics and Engineering

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2008

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Vol. 13, no 4

1003-1018

EN

The Soret driven thermoconvective instability in multicomponent fluids has wide applications in heat and mass transfer. This paper deals with the theoretical investigation of the effect of dust particles on a Soret-driven ferro thermohaline convection heated and soluted from below subjected to a transverse uniform magnetic field in a porous medium. The Brinkmann model is used. An exact solution is obtained for the case of two free boundaries. Both stationary and oscillatory instabilities are investigated using the linear stability analysis and normal mode technique. It is found that the system stabilizes only through stationary mode. The non-buoyancy magnetization parameter, the dust particle parameter and large values of permeability of the porous medium are found to destabilize the system. The Soret coefficient and the stable solute gradient stabilize the system. The results are presented graphically.

10

Effect of rotation on double-diffusive convection in a magnetized ferrofluid with internal angular momentum saturating a porous medium

Sunil, Mahajan A.

International Journal of Applied Mechanics and Engineering

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2008

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Vol. 13, no 4

1059-1078

EN

This paper deals with the theoretical investigation of the effect of rotation in a magnetized ferrofluid with internal angular momentum, heated and soluted from below saturating a porous medium and subjected to a transverse uniform magnetic field. For a flat fluid layer contained between two free boundaries, an exact solution is obtained. A linear stability analysis theory and normal mode analysis method have been employed to study the onset of convection. The influence of various parameters on the onset of stationary convection such as rotation, medium permeability, solute gradient, magnetization and internal angular momentum parameters (i.e., coupling parameter, spin diffusion parameter and heat conduction parameter) has been analyzed. The critical magnetic thermal Rayleigh number for the onset of instability is also determined numerically for sufficiently large values of buoyancy magnetization parameter and results are depicted graphically. The principle of exchange of stabilities is found to hold true for the ferrofluid with internal angular momentum saturating a porous medium heated from below in the absence of rotation, coupling between vorticity and spin, microinertia and solute gradient. The oscillatory modes are introduced due to the presence of the rotation, coupling between vorticity and spin, microinertia and solute gradient, which were non-existent in their absence. In this paper, an attempt is also made to obtain the sufficient conditions for the non-existence of overstability.

11

The influence of the roughness on the Curie temperature and magnetisation in the multilayers

Staniucha A, Urbaniak-Kucharczyk A.

Materials Science Poland

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2006

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Vol. 24, No. 3

701--705

EN

A system of three magnetic (M) layers divided by nonmagnetic (N) spacers is considered. The existence of roughness on the interfaces, described by the model proposed by Bruno and Chappert, leads to a modification of interlayer exchange coupling (IEC). The Curie temperature and magnetisation are calculated using the Green function formalism for the system of layers with Fe standing for M and Cu or Au standing for N. The parameters characterising this system are taken into account for the GaAs substrate. The results obtained show a decreasing Curie temperature with the increasing roughness parameter as compared to the Curie temperature of the sample with an ideal interface. The magnetisation curves are shifted as a result of roughness in the interface region.

12

Magnetisation and Electron Spin Resonance of the colossal magnetoresistive La0.67Ca0.33Mn1-x FexO3

Zając T., Folcik L., Chmist J., Kołodziejczyk A., Drulis H., Krop K., Gritzner G.

Materials Science Poland

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2006

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Vol. 24, No. 3

795--801

EN

We report magnetisation and electron spin resonance (ESR) measurements on colossal magnetoresistive manganites La0.67Ca0.33Mn1-x FexO3 with x = 0, 0.01, 0.03, 0.06, 0.10 and 0.15 in the vicinity of the magnetic (TC) and metal- insulator (TMI) transition temperatures. Above TC the resonance lines with g?2 are caused by the ferromagnetic metallic clusters exhibiting the double exchange interaction between Mn3+-Mn4+ ions. The lines were observed with cooling far below both TC and TMI and were fitted by Dysonian line-shape. Temperature dependences of the linewidths exhibited a minimum value at Tmin?1.25 TC followed by an increase of the width with further cooling toward TC. The anomalous behaviour of the line-width below Tmin is due to an appearance of a ferromagnetic metallic phase within the paramagnetic matrix. The role of phase segregation in which the compounds are phase - separated into a mixture of ferromagnetic and paramagnetic regions is discussed.

13

Domain structures and magnetization processes in thin Co films with in-plane anisotropy

Jaworowicz J., Kurant Z., Postava K., Maziewski A., Baczewski L.T., Wawro A.

Materials Science Poland

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2006

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Vol. 24, No. 3

639--642

EN

The magnetization reversal and domain structures in thin Co films in the thickness range 2 nm

14

Rotating field in induction motor under consideration of anisotropy and cutting strains of steel sheets

Zagradisnik I., Slemnik B.

Journal of Technical Physics

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2002

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Vol. 43, no 4

521-525

EN

The rotating magnetic field in a symmetrical induction machine supplied with a sine-shaped and balanced system shows an asymmetrical shape if the magnetic medium is anisotropic. The shape of the air gap magnetic flux distribution is repeated twice per one revolution of the rotating field in a two-pole machine. The harmonic analyses show that all components rotate with variable magnitudes and non-uniform speeds. The variations are greater if the order of the component is higher. Only odd harmonics occur. Due to the spatial dependence of reluctance and the electric voltage balance in an induction machine, the magnetizing current also shows a spatial dependence.

15

Magneto-static field distribution due to inherent magnetisation of permanent magnets

Pawluk K.

Journal of Technical Physics

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2002

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Vol. 43, no 4

443-452

EN

A boundary-integral model of the static magnetic field due to cylindrical permanent magnets that is put in free space is considered. Magnetic scalar potential quantities created by a virtual quantity "surface magnetic charge density" is expressed by means of Lipschitz-Hankel integrals that for the considered case are reducible (by the way of hypergeometric series) to some algebraic expressions, in which elliptic integrals of various kinds occur. This approach seems to be more effective than that can be reached by the use of a typical professional software for the field problems in which numerical integration, being not quite conform to the considered case, is common. The magnet subjected to the analysis has to be virtually subdivided in some number of elementary pieces, inside of which the uniform distribution of the inherent magnetization is supposed.

16

Magnetization and structure of Fe-Al powders.

Fujii M., Saito K., Wakayama K., Kawasaki M., Yoshioka T., Isshiki T., Nishio K., Shiojiri M.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

860-863

EN

A few micrometers-sized Fe1-xAlx (x=0.35-0.42) powders prepared by atomizing method have the B2 structure and are paramegnetic. The powder milled for several hours is magnetized and has a spontaneous magnetization as great as 100 emu/g. The milled powder particles become flakes, which are composed of lamellae expanding parallel to the (110) plane and having heavily distorted lattice. High-resolution transmission electron microscopy and electron diffraction revealed that structures appear in very thin areas within the lamellae. These superlattices indicate the creation of large number of antiphase boundaries, which induce ferromagnetism. When the milled powder is heated at 100-400 degrees centigrade the magnetization decreases to a few tens emu/g, the lamella structures being kept.

17

Magnetic domain structure of the intermetallic RMn2Ge2 compounds (R identical to La, Ce, Pr, Nd).

Przybył A., Wysłocki J. J., Pawlik P., Szymura S., Levin E. M.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

836-839

EN

Applying the powder pattern method the magnetic domain structures of the polycrystalline intermetallic RMn2Ge2 (where R identical to La, Ce, Pr, Nd) compounds were studied on the grain surfaces parallel and perpendicular to the easy direction of magnetization. The domain structures observed are typical for uniaxial materials. The domain wall energy density gamma was determined from the dependence of the domain width D on the crystal thickness L in the magnetically preferred direction, applying different models of the domain structure. A good agreement was obtained between the values of the domain wall energy as determined from the Kittel's model (gamma = 6,2 mJ/m3) and Hubert's model (gamma = 6,4 mJ/m3 for the LaMn2Ge2 compound.