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    Dataset: RAMS 2009
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    ABSTRACT: The results of the computer simulations of certain electronic properties of the austenite phase of Ni-Mn-Ga alloy are presents. Cluster approach was used and both self-consistent and density functional methods were exploited
    Materials Science Forum 01/2013; 738-739:426-430.
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    ABSTRACT: The paper presents results of the computer simulations and experimental investigation of physical properties of Ni-Mn-Ga alloy. The study was performed using atomic force microscope. The chemical composition of researched specimens causes generation of martensite and austenite phases. Computer simulations are devoted to austenite phase
    Materials Physics and Mechanics 03/2010; 9:53-67.
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    Adam Fraczyk, Teodor Breczko
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    ABSTRACT: Crystallization of amorphous metallic alloy Fe95Si5 (at. %) was investigated using X-ray diffraction measurements performed in-situ during isothermal annealing. Fe95Si5 rib- bons, prepared by melt-spinning, have been analyzed by differential scanning calorimetry (DSC). Their nanostructural evolution has been studied by combining heat treatments with conventional X-ray diffraction. The objective of the experiment was to determine changes in the structural parameters during crystallization of the examined alloy. The crystalline diame- ter and the lattice constant of the crystallizing phase were used as parameters to evaluate structural changes in the material.
    01/2010;
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    ABSTRACT: The martensitic and magnetic domain structures of polycrystalline and single-crystal samples of ferromagnetic Heusler alloys of the Ni-Mn-Ga and Co-Ni-Ga families have been revealed and studied using optical microscopy. The main mechanisms of formation and interaction of 90° and 180° magnetic domains have been described.
    Physics of the Solid State 01/2010; 52(1):101-104. · 0.78 Impact Factor
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    ABSTRACT: A method of localized polarization-optical measurement of dielectric hysteresis loop parameters on microscopical areas of ferroelectric samples combined with simultaneous observation of their domain structure is proposed. A sensitive two-beam differential polarization-optical hysteresisgraph is built for performing the experiments. Examples are given of the study of slow domain structure relaxation processes and dielectric hysteresis curves of lead germanate Pb5Ge3O11.
    Physics of the Solid State 07/2009; 51(7):1497-1499. · 0.78 Impact Factor
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    ABSTRACT: The recently developed ferromagnetic shape memory alloys (FSMA) exhibit large field induced strains thereby rendering new potentials for application in transducers, actuators and other novel devices. Magnetically controlled strain in FSMA is based on the reorientation of the twin structure of martensite under applied magnetic field. A detailed study of both martensitic and magnetic domain structure is presented for oriented single-crystalline bulk and texturized pow-dered samples embedded in polymer matrix, and polycrystalline bulk and rapidly quenched ribbon alloys. Optical microscopy including magneto-optical indicator film technique was employed along-side with X-ray and AFM/MFM studies for the characterization of the coexisting structural and magnetic domains. It is shown that only 180° magnetic domains exist in twin plates because mar-tensite possesses uniaxial magnetic anisotropy having magnetization vector M oriented along easy c-axes at angles of ±45° with respect to the twin boundaries. Due to magnetostatic coupling the 180° magnetic domains of neighbouring twins cooperate with each other forming continuous macrodomains running through the whole crystallite or single crystal sample and changing the direction of M by ±90° in a zigzag fashion at each intersection of the twin boundary.
    Reviews on advanced materials science 01/2009; 20(1):101-106. · 1.29 Impact Factor
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    ABSTRACT: In the Cu-Mn-Al Heusler alloy ternary system the martensitic transformation may pro-ceed in solid solutions having concentration nonuniformities related to small coherent particles forming during the degradation of the high temperature phase and having no spontaneous mar-tensitic transformation on cooling. These particles may have a size well below the critical size of martensite nucleation. In the present work we study the temperature dependence of the structure and magnetic properties of Cu-Mn-Al in the temperature interval including the phase transition. Forward (cooling) and reverse (heating) structural transformations were studied directly by optical microscopy and illustrated by movies showing the motion and transformation pathways of multiple martensite interfaces. Simultaneous temperature measurements of the AC magnetic susceptibil-ity gave a possibility to estimate the volume changes of high-and low-temperature phases during the transformation necessary for modelling the behaviour of this type of alloys.
    Rev.Adv.Mater.Sci. 01/2009; 20:107-111.
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    ABSTRACT: This article reports an computer simulations of physical properties of Heusler NiMnGa alloy. Computer simulation are devoted to austenite phase. The chemical composition of researched specimens causes generation martesite and austenite phases.
    Proc SPIE 07/2008;
  • Teodor Breczko, Andrzej Lempaszek
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    ABSTRACT: Functional materials, of which an example is ferroelectric, ferroelastic monocrystal of molybdate (III) gadolinium (VI), are often used in the micro-motor operators (micro-servo motors) working in changeable environment conditions. Most frequently this change refers to temperature. That is why the important practical problem is the precise measurement of the value of piezoelectric tensor elements in dependence on the temperature of a particular monocrystal. In the presented article for this kind of measurements, the use of X-ray diffractometer has been shown. The advantage of the method presented is that, apart from precise dependence measurement between the temperature of a monocrystal and the value of piezoelectric tensor elements, it enables synchronous measurement of the value of thermal expansion tensor elements for a monocrystal.
    Proc SPIE 04/2007;
  • Teodor Breczko
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    ABSTRACT: The functional properties of crystals have been described by the thermodynamics potential of a crystal. This potential usually is presented as matrix, the elements of which represent physical properties of crystals. Using the partial derivatives we can obtain some physical properties of crystals. In the experimental part of article the results of study of some functional properties of a ferroelastic monocrystal of molybdate (III) gadolinium (VI) are presented.
    Proc SPIE 04/2007;
  • Teodor Breczko, Miroslaw Bramowicz
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    ABSTRACT: In this paper we present results of the investigation of polycrystalline Ni52,2Mn21,3Ga26,5 alloy before and after homogenisation at 1173K processed for different time intervals. We investigated the influence of duration of homogenisation on kinetics of reversible martensitic transformation (RMT). In order to present changes of kinetics of RMT, thermal hysteresis was determined based on calorimetric (DSC) investigation. Our results suggested that thermal annealing at 1173K caused plastic deformation of crystal lattice in the investigated alloy.
    Proc SPIE 04/2007;
  • Alexander I. Melker, Teodor Breczko
    Proc SPIE 04/2007;
  • Teodor Breczko, Janusz Szczepanek
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    ABSTRACT: In the article the results of diffractometric, calorimetric research as well as the chemical constitution have been presented. The research was carried out on the samples made of a thin amorphous tape made with the melt-spinning method from the alloy revealing the memory Ti50Ni25Cu25 effect. The samples were subjected to annealing at different parameters of holding in temperature. After the heat treatment, the response of martensite transformation and formed crystal structures has been observed. The X-ray microstructural tests showed forming so-called outer (top) "free" layer of lamellar precipitation of the high level of coherence.
    Proc SPIE 04/2007;
  • Teodor Breczko, Adam Fronczyk, Krzysztof Kus
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    ABSTRACT: From literature data it can be concluded that physical properties of the amorphous alloys depend on the type of chemical composition. Further modification physical properties of these alloys can be achieved by a proper heat treatment process and structural changes of material. In the paper the experimental results of the Fe97.45Si2.55 amorphous alloy are presented with major attention to determine an influence of isothermal annealing (various temperatures and time periods) on the changes of selected structural parameters in the process of primary crystallization. Hence, lattice constant of crystallized phase, alpha, root-mean-square micro-strains, RMS, and coherent block sizes, D, were established as the structural parameters. These structural characteristics were determined using an X-ray analysis. As a mechanical parameter, we considered a micro-hardness of the heat treated alloy.
    Proc SPIE 04/2005;
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    ABSTRACT: There is no correlation between dimensions of the domain structure elements in an Fe78B12Si9Ni1 amorphous alloy ribbon and the Barkhausen effect characteristics in this alloy in various states: initial, hydrogenated, and annealed. Traditional notions of the Barkhausen effect, the nature of which is related to the domain size and the domain wall mobility, are inapplicable to disordered systems such as magnetically soft amorphous metal alloys.
    Technical Physics Letters 05/2004; 30(5). · 0.58 Impact Factor
  • Teodor M. Breczko, Krzysztof Kus, Janusz Szczepanek
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    ABSTRACT: Shape memory alloys (SMA's) have become one of the major elements of intelligent structures and mechanisms (e.g. sensors, actuators, and active biomaterials) due to their unique thermo-mechanical properties. The main features of SMA's are related to a reversible martensitic transformation that can be induced either thermally or by applying stress. In this study, crystalline structure and changes in phase composition of TiNiCu samples were investigated mainly using an X-ray diffraction (XRD) method. Amorphous ribbons with the composition of Ti50Ni25Cu25 were characterized under various temperatures during annealing. Changes in crystalline structure have been shown to be dependent on the executed processes. XRD measurement results revealed that heat treatment annealing yields totally the crystalline structure of amorphous structure and martensite is the major phase.
    Proc SPIE 01/2004;
  • Teodor M. Breczko, Miroslaw Bramowicz
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    ABSTRACT: In this paper the influence of work parameter of magnetic force microscopy (MFM) on the magnetic contrast of the stray field measured in soft magnetic amorphous Fe-based ribbons using two-pass technique has been analyzed. It was proved that an increase in DeltaZ separation of sample-tip during the second scan affects considerably the quality, contrast of obtained micrograph of the stray field image. Increase in &DeltaZ causes smaller interaction between the cantilever's tip and tested field. It is caused by smaller influence of the source field emitted from the sample on the magnetic tip. Detirioration and contrast's broadening of obtained pictures allows to analyze and detect the areas which have positive as well as negative magnetization.
    Proc SPIE 01/2004;
  • Teodor M. Breczko, Krzysztof Kus
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    ABSTRACT: Structural characteristics of the austenite phase of a NiTi shape memory alloy (SMA) subjected to thermo-mechanical cycling under a constant applied load were studied. Progressive thermo-mechanical action of the external deformation results in both changes of the defect structure and, macroscopically, in memory shape effect degradation. The study was performed using the x-ray method of analysis. Two parameters have been determined to study the evolution of the austenite phase: root-mean-square (RMS) microstrains and coherent block size. the number of thermoa-mechanical loading cycles was varied either from 50 to 400 (for series) or from 1 to 5 for preliminary estimates. Experimental results show that the loading process depends on the changes in the structural cahracteristics. On this basis we propose some structural parameters helpful in the prediction of the memory shape effect degradation in the actuated SMA materials.
    Proc SPIE 10/2003;

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