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    Wyświetlanie 1-13 z 13
    Tytuł:
    Study of factors determinant of siliceous electrical porcelain resistance to structural degradation
    Autorzy:
    Ranachowski, P.
    Ranachowski, Z.
    Kudela Jr., S.
    Pawełek, A.
    Piątkowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/351813.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    porcelain insulating materials
    ageing processes
    acoustic emission (AE)
    optical microscopy
    Opis:
    The subject of this study was investigation of the factors that have a decisive influence on the resistance of siliceous porcelain to degradation processes. There was tested material C 110 type, which is widely used for the production of low-voltage (LV) elements such as insulators and bushings. On the basis of mechanical-acoustic and microscopic research of small-sized samples, which were subjected to compression, there were distinguished successive stages of degradation of the material structure. In the authors* opinion, they have a reference to the ageing process, taking place during many years of work under operating conditions. Thus, it was possible to assess the structural factors that determine the durability and reliability of LV electroinsulating elements. The results were related to electrical aluminous porcelains.
    Źródło:
    Archives of Metallurgy and Materials; 2016, 61, 3; 1489-1496
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Quasi-Static and Dynamic Testing of Carbon Fiber Reinforced Magnesium Composites
    Autorzy:
    Ranachowski, Z.
    Ranachowski, P.
    Brodecki, A.
    Kopeć, M.
    Kudela, S. jr.
    Powiązania:
    https://bibliotekanauki.pl/articles/351742.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Mg matrix composite
    compressive properties
    carbon fiber
    Split-Hopkinson Pressure Bar
    Opis:
    Two types of composites, consisting of pure magnesium matrix reinforced with two commercially used carbon fibers, were systematically studied in this paper. The composites fabricated by the pressure infiltration method, were subjected to quasistatic and dynamic compression tests. Morphology of fiber strands was observed using scanning electron microscope (SEM). The application of carbon fibre reinforcement led to the stiffening of tested materials, resulting in the limitation of the possible compression to approx. 2.5%. The performed tests revealed the remarkable difference in compression strength of investigated compositions. The cause of that effect was that GRANOC fiber reinforced composite exhibited insufficient bond quality between the brittle fibers and the ductile matrix. T300 reinforced composite presented good connection between reinforcement and matrix resulting in increased mechanical properties. Investigated composites demonstrated higher mechanical strength during deformation at high strain rates. Microscopic observations also proved that the latter fibers with regular shape and dense packaging within the filaments are proper reinforcement when designing the lightweight composite material.
    Źródło:
    Archives of Metallurgy and Materials; 2020, 65, 2; 893-899
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of Modified Aluminous Porcelain Subjected to Mechanoacoustic Tests
    Autorzy:
    Ranachowski, P.
    Ranachowski, Z.
    Wieczorek, K.
    Jaroszewski, M.
    Kudela, S. jr.
    Powiązania:
    https://bibliotekanauki.pl/articles/355059.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    electrical porcelain materials
    ageing processes
    acoustic emission
    AE
    optical microscopy
    Opis:
    The paper presents the microscopic and mechanoacoustic study of degradation processes of the porcelain material C 130 type. This kind of material is used in the production of the most durable and reliable electrotechnical elements. Raw material composition of the studied porcelain was modified. This had an impact on the inner properties, cohesion and – in consequence – on operational properties of the material. Using mechanical-acoustic and microscopic methods of testing of small-size samples that were subjected to compression, it was possible to distinguish successive stages of degradation of the porcelain structure. These stages were generally typical of the porcelain materials. In the authors’ opinion, they are connected to the ageing process happening over many years of work under operating conditions. Optimization of composition and technological properties – important during technological processes – resulted in a slight decrease in inner cohesion of the porcelain. When compared to the reference material – typical domestic C 130 material, mechanical strength was somewhat lower. Carried out investigations proved that resistance of the investigated material to the ageing degradation process – during long term operation – also decreased. The improvement of technological parameters and the reduction in the number of defective elements occurred simultaneously with some decrease in the operational parameters of the material. To restore their initial high level, further work is needed to optimize the raw material composition of the porcelain.
    Źródło:
    Archives of Metallurgy and Materials; 2018, 63, 4; 1821-1826
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mechanical Spectroscopy of MgB2 Containing SiC
    Spektroskopia mechaniczna MgB2 zawierającego SiC
    Autorzy:
    Silva, M. R.
    Silva, L. B. S.
    Rodriques Jr., D.
    Grandini, C. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/355880.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    mechanical spectroscopy
    internal friction
    anelasticity
    MgB2
    SiC
    spektroskopia mechaniczna
    tarcie wewnętrzne
    właściwości anelastyczne
    Opis:
    The compound magnesium diboride (MgB2) has been well-known since the 1950s; however, its superconducting properties were unknown. Intrinsic characteristics of MgB2 make this material a promising candidate for technological applications, although the low value of the irreversibility field and the decrease in critical current density with the increase in the magnetic field considerably reduce its utility. The present work aimed to study the effect of carbon-based doping on anelastic properties of MgB2 as measured by mechanical spectroscopy. The samples were prepared by using the powder-intube method. The samples were made with 5, 7.5, and 10 wt.% of silicon carbide (SiC). The results reveal complex mechanical loss spectra caused by the interaction between point defects and surface defects in the crystalline lattice of MgB2.
    Dwuborek związek magnezu (MgBV) jest znany od 1950 roku; jednak jego właściwości nadprzewodzące były nieznane. Swoiste cechy MgB2 czynią ten materiał obiecującym kandydatem do zastosowań technicznych, jednak niskie wartości nieodwracalnego pola i zmniejszenie krytycznej gęstości prądu ze wzrostem pola magnetycznego znacznie zmniejszają jego użyteczność. Celem pracy było zbadanie wpływu domieszkowania związkiem węgla na anelastyczne właściwości MgB2 mierzone metodą spektroskopii mechanicznej. Próbki zostały przygotowane za pomocą metody powder-in-tube (PIT). Wytworzono próbki o zawartości 5, 7.5 i 10 % wag. węglika krzemu (SiC). Wyniki pokazują złożone widma strat mechanicznych powodowanych przez wzajemne oddziaływanie pomiędzy defektami punktowymi i defektami powierzchniowymi w sieci krystalicznej MgB2.
    Źródło:
    Archives of Metallurgy and Materials; 2015, 60, 4; 3083-3086
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of the mullite hypothesis in respect of electrotechnical porcelains
    Ocena mulitowej teorii wzmocnienia w zastosowaniu do porcelan elektrotechnicznych
    Autorzy:
    Ranachowski, P.
    Rejmund, F.
    Ranachowski, Z.
    Pawełek, A.
    Piątkowski, A.
    Kudela Jr., S.
    Powiązania:
    https://bibliotekanauki.pl/articles/352850.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    electrotechnical porcelain
    porcelain degradation
    acoustic emission (AE)
    microscopic analysis
    porcelana elektrotechniczna
    degradacja porcelany
    emisja akustyczna (EA)
    analiza mikroskopowa
    Opis:
    The paper presents the evaluation of the mullite hypothesis explaining the strength of porcelains. There was researched the influence of the mullite phase on the short- and long-term mechanical strength of electrotechnical porcelain of different types (C 110, C 112, C 120 and C 130). The total mullite phase content, the size and distribution of precipitates and dispersed single crystals in the glassy matrix were considered. Mechanoacoustic and microscopic techniques as well as ultrasonic testing were used during the investigation. The role of the mullite phase in the increase of strength and resistance to aging processes of electrical porcelain of various types was described. Mullite hypothesis is valid in reference to siliceous (C 110), cristobalite (C 112) and aluminous C 120 type materials of a typical raw components content and phase composition. In the case of modern strengthened C 120 and C 130 type aluminous materials advantageous are only dispersed fine mullite needles. The precipitates of mullite phase, especially of bigger size, are undesirable.
    W pracy przedstawiono ocenę teorii mulitowej wzmocnienia porcelany, w odniesieniu do tworzyw elektrotechnicznych. Przedmiotem badań był wpływ fazy mulitowej na krótko- i długotrwałą wytrzymałość mechaniczną elektroporoelan rodzaju C 110, C 112, C 120 oraz C 130. Rozpatrywana była sumaryczna zawartość fazy mulitowej. wielkość i rozłożenie jej wydzieleń oraz niezaglomeryzowanych kryształów w osnowie szklistej. W badaniach wykorzystano metodę mechanoakustyczną, techniki mikroskopowe (MO i SEM) oraz metodę ultradźwiękową. Przedstawiono rolę fazy mulitowej w podwyższeniu odporności na procesy starzeniowe porcelany elektrotechnicznej różnego rodzaju. Stwierdzono słuszność teorii mulitowej w przypadku tworzyw kwarcowych (C 110), krystobalitowych (C 112) oraz wysokoglinowych rodzaju C 120 o typowym - tradycyjnym składzie surowcowym i fazowym. W zastosowaniu do nowoczesnych, wzmocnionych tworzyw wysokoglinowych rodzaju C 120 oraz porcelan rodzaju C 130 korzystnie działają rozproszone w osnowie, niezaglomeryzowane igłowe kryształy mulitu. Wydzielenia mulitu, zwłaszcza o większych rozmiarach, są niepożądane.
    Źródło:
    Archives of Metallurgy and Materials; 2013, 58, 4; 1177-1181
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Degradation Processes in Shield-Centring Elements of Surge Arresters
    Autorzy:
    Papliński, P.
    Śmietanka, H.
    Ranachowski, P.
    Ranachowski, Zbigniew
    Wieczorek, K.
    Kudela, S. jr.
    Powiązania:
    https://bibliotekanauki.pl/articles/2203744.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    surge arrester
    TSE glass textolite
    discharge current
    EDS method
    Opis:
    This paper presents the results of testing samples of shield-centering elements from medium-voltage surge arresters. The elements were made of TSE glass textolite. The elements have been dismantled from different operated surge arresters, which were subjected to discharge currents (short-circuit currents) of different intensity and duration. The discharge currents led to degradation of the tested elements with various degrees of advancement. The degradation was investigated using microscopic methods and energy-dispersive X-ray spectroscopy (EDS). Changes in the content of elements of the surface of textolite materials - as the degradation progresses - were documented. It was found that high discharge current flows resulted in melting of the organic binder, epoxy resin, especially its surface layer. Partial charring and even burning of the resin was noticeable. Furthermore, it was found that with increasing degradation on the surface of the TSE laminate, the carbon and oxygen content, which are part of the organic resin, decreases. Simultaneously the amount of silicon, calcium and aluminium, which are present in the glass fibres, increases. The charring effect of the resin and the formation of conductive paths result in a decrease in the performance of surge arresters and their subsequent failure.
    Źródło:
    Archives of Metallurgy and Materials; 2023, 68, 1; 237--242
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Internal Friction and Microstructure of Ti and Ti-Mo Alloys Containing Oxygen
    Autorzy:
    Martins Jr, J. R. S.
    Araújo, R. O.
    Nogueira, R. A.
    Grandini, C. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/351840.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    mechanical spectroscopy
    anelasticity
    internal friction
    Ti-Mo alloys
    interstitials
    biomaterials
    Opis:
    Ti-Mo alloys are promising materials for use as biomaterials, because these alloys have excellent corrosion resistance and a good combination of mechanical properties such as fatigue, low elastic modulus, hardness, and wear resistance. The objective of this paper was to study the effect of heavy interstitial atoms on anelastic properties of Ti-Mo alloys using mechanical spectroscopy. The internal friction and Young’s modulus were measured as a function of temperature using dynamic mechanical analyser. The internal friction spectra were brought about by relaxation processes attributed to shortrange stress induced reorientation of interstitial and substitutional complexes in solid solution. It is suggested that the nature of the relaxing entities can be worked out in further research on Ti-Mo single crystals.
    Źródło:
    Archives of Metallurgy and Materials; 2016, 61, 1; 25-30
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Statistical Assessment of the Microstructure of Barite Aggregate from Different Deposits Using X-Ray Microtomography and Optical Microscopy
    Autorzy:
    Żołek, N.
    Ranachowski, Z.
    Ranachowski, P.
    Jóźwiak-Niedźwiedzka, D.
    Kudela, S. jr.
    Dvorak, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/351890.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    barite ore
    barite aggregate
    microstructure
    optical microscopy
    thin sections analysis
    X-ray tomography
    Opis:
    Two different barite ore (barium sulfate BaSO4) specimens from different localizations were tested and described in this paper. Analysis of the microstructure was performed on polished sections, and on thin sections using X-ray microtomography (micro-CT), and optical microscopy (MO). Microtomography allowed obtaining three-dimensional images of the barite aggregate specimens. In the tomograms, the spatial distribution of the other polluting phases, empty space as well as cracks, pores, and voids – that exceeded ten micrometers of diameter-were possible to visualize. Also, the micro-CT allowed distinguishing between minerals of different density, like SiO2 and BaSO4. Images obtained and analyzed on thin sections with various methods using the optical microscopy in transmitted light delivered additional information on the aggregate microstructure, i.e. allow for estimation of the different kinds of inclusions (like the different density of the minerals) in the investigated specimens. Above methods, which were used in the tests, completed each another in order to supply a set of information on inclusions’ distribution and to present the important differences of the barite aggregate specimens microstructure.
    Źródło:
    Archives of Metallurgy and Materials; 2017, 62, 2A; 697-702
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Determination Of Diffusive Tortuosity In Concrete Specimens Using X-Ray Microtomography
    Wyznaczanie krętości dyfuzyjnej w próbkach betonów przy zastosowaniu metody mikrotomografii rentgenowskiej
    Autorzy:
    Ranachowski, Z.
    Jóźwiak-Niedźwiedzka, D.
    Ranachowski, P.
    Dąbrowski, M.
    Kudela Jr., S.
    Dvorak, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/354949.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    X-ray tomography
    concrete microstructure
    diffusive tortuosity
    tomografia rentgenowska
    mikrostruktura betonu
    krętość dyfuzyjna
    Opis:
    The paper presents a method of pore connectivity analysis applied to specimens of cement based composites differing in water to cement ratio. The method employed X-ray microtomography (micro-CT). Microtomography supplied digitized three-dimensional radiographs of small concrete specimens. The data derived from the radiographs were applied as an input into the application based on the algorithm called ‘random walk simulation’. As the result a parameter called diffusive tortuosity was established and compared with estimated porosity of examined specimens.
    Artykuł prezentuje metodę wyznaczania parametru charakteryzującego intensywność połączeń mikroporów w zastosowaniu do próbek kompozytów z matrycą cementową, różniących się stosunkiem wodnocementowym. Metoda bazuje na wynikach badań z zastosowaniem mikrotomografii rentgenowskiej. Analizowano zdigitizowane zestawy danych, opisujące trójwymiarową reprezentację mikrostruktury niewielkich próbek wykonanych z betonu. Przygotowane w ten sposób skany mikrostruktury zastosowano jako dane wejściowe wprowadzone do oprogramowania wykorzystujacego algorytm ‘przypadkowo migrujących cząstek wirtualnych’. W ten sposób wyznaczono parametr mikrostruktury znany jako krętość dyfuzyjna. Parametr ten porównano z porowatością obserwowaną wyznaczoną dla zbadanych próbek przy wykorzystaniu analizy jasności voxeli w analizowanych próbkach.
    Źródło:
    Archives of Metallurgy and Materials; 2015, 60, 2A; 1115-1119
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparative Studies on Degradation of Varistors Subjected to Operation in Surge Arresters and Surge Arrester Counters
    Autorzy:
    Papliński, P.
    Wańkowicz, J.
    Śmietanka, H.
    Ranachowski, P.
    Ranachowski, Z.
    Kudela, S. jr.
    Aleksiejuk, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/351611.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    surge arrester
    surge arrester counter
    MO varistor
    microstructure of ceramics
    ceramic material degradation
    Opis:
    The paper presents results of investigation of microstructure and micro-hardness for material of ZnO varistors applied to 110 kV surge arrester and surge arrester counter. The research combined two pairs of varistors, each consisted of one varistor subjected before to operation, while the other one was brand new unit and constituted a reference. All varistors were made of the same material by the reputable manufacture. The tests revealed a different degree of the material degradation for varistors subjected before to operation. This also refers to different degradation mechanism observed for the material of these varistors, if typical effects of degradation of aged ZnO varistors were considered as a reference. Physical state of spinel in the microstructure had a significant impact on the material degradation, however a considerable loosening of the microstructure associated with bismuth oxide was observed too. It was surprising, since the precipitates of the bismuth oxide phase most often showed very good binding to the ZnO matrix and high resistance to associated electrical, thermal and mechanical effects. The degradation effects in the ZnO matrix proved to be limited only.
    Źródło:
    Archives of Metallurgy and Materials; 2020, 65, 1; 367-374
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of X-Ray Microtomography and Optical Microscopy to Determine the Microstructure of Concrete Penetrated by Carbon Dioxide
    Zastosowanie mikrotomografii komputerowej i mikroskopii optycznej do oceny mikrostruktury betonów poddanych działaniu CO2
    Autorzy:
    Ranachowski, Z.
    Jóźwiak-Niedźwiedzka, D.
    Ranachowski, P.
    Rejmund, F.
    Dąbrowski, M.
    Kudela, S. jr.
    Dvorak, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/351864.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    cement-matrix composites
    concrete deterioration
    X-ray tomography
    microscopic analysis
    concrete microstructure
    kompozyty cementowe
    zniszczenie betonu
    tomografia rentgenowska
    analiza mikroskopowa
    mikrostruktura betonu
    Opis:
    In the paper two advanced methods for testing cement based composites are described and compared. These are X-ray microtomography and optical microscopy. Microtomography supplies three-dimensional images of small concrete specimens. In the tomograms all cracks, pores and other voids and inclusions, that exceed a few micrometers, are shown. Such visualisation can become a valuable tool for analysis of the basic material properties. Images obtained on thin sections and analysed with various methods on optical microscopes supply additional information on material microstructure that cannot be obtained in tomograms. For example it is relatively easy to determine zone penetrated by CO2 ingress. These two methods, presented on examples of tests, complete each another in order to supply a set of information on composition and defects of tested composite materials.
    W artykule przedstawiono dwie nowoczesne metody analizy struktury materiałów kompozytowych ze spoiwem na bazie cementu. Są to mikrotomografia komputerowa oraz optyczna analiza cienkich szlifów. Mikrotomografia pozwala na uzyskanie trójwymiarowych obrazów niewielkich próbek betonowych. Na tomogramach widoczne są układy rys, porów i innych pustek, których wymiary przekraczają kilka mikrometrów. Przestawienie tych obiektów w przestrzeni jest ważnym narzędziem do analizy podstawowych właściwosci materiału. Obrazy uzyskane na cienkich szlifach w mikroskopie optycznym, analizowane następnie różnymi metodami, dostarczają dodatkowych informacji o mikrostrukturze materiału, które nie mogą być dostrzeżone na tomogramach. Stosunkowo łatwo jest np. uzyskac obrazy stref skarbonatyzowanej matrycy cementowej. Obie przedstawione metody uzupełniają się wzajemnie i pozwalają na otrzymanie zbioru informacji o składzie i defektach badanych materiałów kompozytowych.
    Źródło:
    Archives of Metallurgy and Materials; 2014, 59, 4; 1441-1447
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of the Phase Transitions in BNT-BT Lead-Free Ceramics Around Morphotropic Phase Boundary by Mechanical and Dielectric Spectroscopies
    Autorzy:
    Silva Jr, P. S.
    Diaz, J. C. C. A.
    Florêncio, O.
    Venet, M.
    M’Peko, J. C.
    Powiązania:
    https://bibliotekanauki.pl/articles/353072.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Lead-free piezoelectric ceramics
    morphotropic phase boundary
    phase transitions
    mechanical spectroscopy
    dielectric spectroscopy
    Opis:
    In this work, the syntheses and characterization by mechanical and dielectric spectroscopies of (1-x) Bi0.5Na0.5TiO3-xBaTiO3 (BNT-100xBT), with x = 0.05, 0.06 and 0.07, lead-free piezoelectric ceramics is reported. Ceramic samples of BNT-BT have been prepared by mixed-oxide method and then conventionally sintered. X-ray diffraction patterns of sintered samples, indicated for BNT-7BT the presence of tetragonal (P4mm) complex perovskite structure, whereas for BNT-5BT and BNT-6BT the samples exhibit a mixture of tetragonal (P4mm) and rhombohedral (R3c) crystalline phases, which reveal the presence of a morphotropic phase boundary (MPB) in the BNT-BT system. Measurements of internal friction, Q-1, and the storage modulus, E’, as a function of temperature at various frequencies were carried out in a Dynamic Mechanical Analyzer (DMA), in the temperature range from 0ºC to 600ºC. Dielectric profiles are recorded in the frequency range from 1kHz to 100kHz and the temperature range from room temperature to 475ºC. Mechanical loss spectra obtained for investigated compositions of BNT-BT samples showed different frequency-independent anomalies. Two main anomalies for BNT-5BT and BNT-6BT, observed around 100ºC and 430ºC were associated with the ferroelectric-antiferroelectric and antiferroelectricparaelectric phase transitions, respectively. The results obtained from mechanical loss measurements were supported by dielectric relaxation spectra. For BNT-7BT, outside the MPB, four different frequency-independent processes were observed.
    Źródło:
    Archives of Metallurgy and Materials; 2016, 61, 1; 17-20
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Plastic Instabilities Induced by the Portevin - Le Châtelier Effect and Fracture Character of Deformed Mg-Li Alloys Investigated Using the Acoustic Emission Method
    Autorzy:
    Pawełek, A.
    Piątkowski, A.
    Wajda, W.
    Skuza, W.
    Tarasek, A.
    Ranachowski, Z.
    Ranachowski, P.
    Ozgowicz, W.
    Kúdela, Jr.
    Kúdela, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/353865.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    lightweight alloys
    acoustic emission
    fracture
    Portevin-Le Châtelier phenomenon
    twinning
    dislocations
    shear bands
    Opis:
    The results of the investigation of both mechanical and acoustic emission (AE) behaviors of Mg4Li5Al and Mg4Li4Zn alloys subjected to compression and tensile tests at room temperature are compared with the test results obtained using the same alloys and loading scheme but at elevated temperatures. The main aim of the paper is to investigate, to determine and to explain the relation between plastic flow instabilities and the fracture characteristics. There are discussed the possible influence of the factors related with enhanced internal stresses such as: segregation of precipitates along grain boundaries, interaction of solute atoms with mobile dislocations (Cottrell atmospheres) as well as dislocation pile-ups which may lead to the microcracks formation due to the creation of very high stress concentration at grain boundaries. The results show that the plastic flow discontinuities are related to the Portevin-Le Châtelier phenomenon (PL effect) and they are correlated with the generation of characteristic AE pulse trains. The fractography of broken samples was analyzed on the basis of light (optical), TEM and SEM images.
    Źródło:
    Archives of Metallurgy and Materials; 2016, 61, 2A; 897-904
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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