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Wyszukujesz frazę "Kovacova, A." wg kryterium: Autor


Wyświetlanie 1-9 z 9
Tytuł:
Post SPD Materials Recovery in Thermal Exposition
Autorzy:
Kvačkaj, T.
Kováčová, A.
Kočiško, R.
Powiązania:
https://bibliotekanauki.pl/articles/1402127.pdf
Data publikacji:
2015-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Bx
81.07.-b
81.20.Hy
81.40.Cd
Opis:
The mechanical and thermo-physical properties of Cu-Cr-Zr alloys in dependence on processing conditions were studied. The processing conditions consisted of solution annealing at temperature of 1020°C for 60 min followed by water quenching. This was followed by one equal channel angular pressing pass carried out at ambient temperature, ageing treatment ($T_{AT}$∈ (20;480⟩°C, $t_{AT}$∈ ⟨30;150⟩ min) and cooling in water. The maximal strengthening effect coming from dislocations & grain size refinement & precipitation strengthening of ΔHV0.1=130 was achieved at $T_{AT}$=480°C and for $t_{AT}$=120 min. From differential scanning calorimetry analysis, two partial exothermal peaks were recognized and classified as major and minor, these peaks are used to determination the stored energy coming from recrystallization and precipitation ($\Delta H_R$ and $\Delta H_P$). The maximal value in stored energy of $H_{1 \times \text{ECAP}} = 2.923 J//g$ was obtained after 1st ECAP pass.
Źródło:
Acta Physica Polonica A; 2015, 128, 4; 689-692
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New Approach In The Properties Evaluation Of Ultrafine-Grained OFHC Copper
Nowe podejście do oceny właściwości ultra drobnoziarnistej miedzi OFHC
Autorzy:
Kvačkaj, T.
Kováčová, A.
Bidulská, J.
Bidulský, R.
Kočičko, R.
Powiązania:
https://bibliotekanauki.pl/articles/958234.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
OFHC copper
UFG
ECAP
strain rate
fractography
wear resistance
miedź OFHC
szybkość odkształcenia
fraktografia
odporność na zużycie
Opis:
In this study, static, dynamic and tribological properties of ultrafine-grained (UFG) oxygen-free high thermal conductivity (OFHC) copper were investigated in detail. In order to evaluate the mechanical behaviour at different strain rates, OFHC copper was tested using two devices resulting in static and dynamic regimes. Moreover, the copper was subjected to two different processing methods, which made possible to study the influence of structure. The study of strain rate and microstructure was focused on progress in the mechanical properties after tensile tests. It was found that the strain rate is an important parameter affecting mechanical properties of copper. The ultimate tensile strength increased with the strain rate increasing and this effect was more visible at high strain rates (έ~102s−1) . However, the reduction of area had a different progress depending on microstructural features of materials (coarse-grained vs. ultrafine-grained structure) and introduced strain rate conditions during plastic deformation (static vs. dynamic regime). The wear behaviour of copper was investigated through pin-on-disk tests. The wear tracks examination showed that the delamination and the mild oxidational wears are the main wear mechanisms.
W pracy zbadano szczegółowo statyczne, dynamiczne i tribologiczne właściwości ultra drobnoziarnistej (UFG) beztlenowej miedzi o wysokiej przewodności cieplnej (OFHC). W celu oceny właściwości mechanicznych przy różnych szybkościach odkształcenia, miedź OFHC badano za pomocą dwóch urządzeń w warunkach statycznych i dynamicznych. Ponadto miedź poddano dwóm różnym sposobom przetwarzania, co umożliwiło badanie wpływu struktury. Badanie szybkości odkształcenia i mikrostruktury koncentrowało się na zmianie właściwości mechanicznych po próbie rozciągania. Stwierdzono, że szybkość odkształcania jest ważnym parametrem wpływającym na właściwości mechaniczne miedzi. Wytrzymałość na rozciąganie wzrosła ze wzrostem szybkości odkształcenia i ten efekt był bardziej widoczny przy dużej szybkości odkształcania (ε~102s−1) . Jednak zmniejszenie obrazu przebiegało inaczej w zależności od cech mikrostruktury materiałów (struktura gruboziarnista a struktura ultra drobnoziarnista) i zadanych warunków szybkości odkształcenia podczas odkształcenia plastycznego (warunki statyczne a warunki dynamiczne). Zużycie miedzi badano za pomocą testów zarysowania. Badanie ścieżek zużycia wykazało, że delaminacja i umiarkowane utlenienie to główne mechanizmy zużycia.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2A; 605-614
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Material Recovery of OFHC Cu and FeSi Steel after Processing by Plastic Deformations
Autorzy:
Kvackaj, T.
Kocisko, R.
Bidulska, J.
Luptak, M.
Kovacova, A.
Powiązania:
https://bibliotekanauki.pl/articles/1032938.pdf
Data publikacji:
2017-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.82.Bg
07.20.Mc
81.20.Wk
62.20.F-
81.40.Ef
Opis:
The influence of thermoplastic processes through severe plastic deformations carried out at ambient temperature and through rolling carried out at cryogenic temperature on the recovery for two types of materials was investigated. As experimental materials, there were used oxygen free high conductivity copper and FeSi steel presenting materials with middle and high stacking fault energy, respectively. Both materials have been previously investigated, however mainly considering their material properties. In this study, oxygen free high conductivity Cu was processed by 13 passes through equal channel angular rolling which belongs to the severe plastic deformations group of methods. The rolling of FeSi steel at ambient and cryogenic temperatures was performed using a laboratory duo rolling mill, samples were rolled only by one pass. The aim of this study was to insert the strain to the materials with different stacking fault energy (middle and high) under ambient and cryogenic thermal conditions, respectively, and subsequently to observe the influence of stored energy on structural recovery of materials through differential scanning calorimetry method. This study implies that the recovery process characterized by the mobility of structural defects begins earlier for FeSi steel compared to oxygen free high conductivity Cu.
Źródło:
Acta Physica Polonica A; 2017, 131, 5; 1315-1318
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of Severe Plastic Deformation and Heat Treatment on CuCrZr Alloys
Autorzy:
Kováčová, A.
Kvačkaj, T.
Kočiško, R.
Dragošek, L.
Lityńska-Dobrzyńska, L.
Powiązania:
https://bibliotekanauki.pl/articles/1032905.pdf
Data publikacji:
2017-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Bx
81.40.Cd
61.72.Ff
Opis:
CuCrZr alloy was subjected to equal channel angular pressing method, belonging to the severe plastic deformation group, followed by heat treatment under different ageing conditions to optimize mechanical properties of the alloy. Before equal channel angular pressing, CuCrZr alloy was treated by solution annealing at temperature 1020°C for 1 h. Afterwards, samples were pressed through an equal channel angular pressing die once at room temperature and subjected to artificial ageing under different conditions (200, 400, 450, 480°C for 30, 60, 90, 120, 150 min). Optimization of the CuCrZr alloy was done through the study of mechanical properties and microhardness as a function of ageing temperature and time considering the progress in microstructural/substructural features.
Źródło:
Acta Physica Polonica A; 2017, 131, 5; 1336-1339
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of the Ultrafine-Grained Structure Formation Under Different Strain Rates
Autorzy:
Kováčová, A.
Kvačkaj, T.
Bidulský, R.
Bidulská, J.
Kočiško, R.
Dutkiewicz, J.
Lityńska-Dobrzyńska, L.
Powiązania:
https://bibliotekanauki.pl/articles/353994.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
electron microscopy
EBSD
nanostructured materials
equal channel angular processing
grain refinement
Opis:
The present paper deals with a study on formation of specific substructural features in OFHC copper processed by equalchannel angular pressing (ECAP) considering different strain rate conditions. Since two mechanical tensile testing equipments were being used, strain rate response could be studied in a wide range (both in static and dynamic regimes). Moreover, the copper before tensile testing was subjected to drawing and ECAP, separately, which allows to study the influence of both structural and substructural features (CG vs. UFG structure). Considering the static regime, it was found that UFG materials have advanced properties, showing higher strength and ductility in comparison to their CG counterparts. However, this is valid only to the critical value of the strain rate. In the dynamic regime, mathematical linearized results imply that ultimate tensile strength in samples processed by ECAP increases twice every 10 s-1 rising, however, they lost approximately the same plastic properties than samples after drawing. Differences in the progress of mechanical properties are related to specific structural and substructural features evolved in the material during ECAP processing. Above mentioned features were studied in detail by methods of transmission and scanning electron microscopy (TEM, SEM).
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2A; 851-856
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Annealing Conditions on Structural Development of Cryo Rolled FeSi Steel
Autorzy:
Kvackaj, T.
Bidulska, J.
Bidulsky, R.
Kovacova, A.
Kocisko, R.
Bella, P.
Luptak, M.
Bacso, J.
Powiązania:
https://bibliotekanauki.pl/articles/1367991.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Bb
81.05.Bx
81.40.Rs
81.40.Ef
Opis:
Non grain oriented isotropic electrical steels, commercially called NGOES, were investigated in cryogenic temperature conditions. At cryogenic temperatures plastic deformations form strong structural heterogeneities in the sample thickness. Samples processed by cryo rolling show a bigger storage energy. To achieve abnormal grain growth through the process of static recrystallization, the annealing conditions were applied to the deformed samples. Moreover, minimal magnetic losses were reached when mean grain size diameter was approximately 150 μm.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 184-185
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of workability test to SPD processing
Zastosowanie testu obrabialności do intensywnego odkształcenia plastycznego
Autorzy:
Kvačkaj, T.
Kočiško, R.
Tiža, J
Bidulská, J.
Kováčová, A
Bidulský, R
Bascó, J
Vlado, M.
Powiązania:
https://bibliotekanauki.pl/articles/351817.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
compression test
powder metallurgy
fracture criteria
ECAR
Deform 3D
próba ściskania
metalurgia proszków
kryteria pękania
Opis:
The aluminium alloy with chemical conception AlMgSi prepared by PM (powder metallurgy) technology was used. The experiments such as a ring and compression test, ECAR (equal channel angular rolling) for determination of friction coefficient, stress-strain curves and material workability based on analytical methods (Freudenthal, Cockcroft-Latham and normalized Cockcroft-Latham criteria) were performed. Numerical simulations of sample processed by ECAR was carried out by a software Deform 3D with focus on the description of stress, strain fields and workability criteria (Cockcroft-Latham and normalized Cockcroft-Latham). The prediction of fracture formations in a real ECAR sample during processing conditions was also done.
Stop aluminium o składzie chemicznym AlMgSi przygotowano metodą proszkową. Wykonano badania takie jak próba ściskania swobodnego pierścieni i walcowatych, ECAR (wyciskanie w kanale kątowym z walcowaniem) w celu wyznaczenia współczynnika tarcia, krzywych naprężenie-odkształcenie oraz podatności materiału na odkształcenie z użyciem metod analitycznych (kryterium Freudenthal, Cockcroft-Latham i znormalizowane Cockcroft-Latham). Symulacje numeryczne dla próbki poddawanej procesowi ECAR przeprowadzono przy pomocy oprogramowania Deform 3D z naciskiem na opis pól sił i naprężeń oraz kryteriów obrabialności (Cockcroft-Latham i znormalizowane Cockcroft-Latham). Przeprowadzono również symulacje mozliwości tworzenia się pęknięć w rzeczywistej próbce poddanej procesowi ECAR.
Źródło:
Archives of Metallurgy and Materials; 2013, 58, 2; 407-412
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical and Structural Properties of High Purity Al Processed by ECAP
Autorzy:
Kvačkaj, T.
Kočiško, R.
Pokorný, I.
Bidulská, J.
Kvačkaj, M.
Kováčová, A.
Bidulský, R.
Lityńska-Dobrzyńska, L.
Dutkiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/1418957.pdf
Data publikacji:
2012-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Bx
81.07.-b
81.20.Hy
81.40.-z
Opis:
The mechanical properties and substructure formation of high purity aluminium (99.999%) processed by severe plastic deformation method (equal channel angular pressing) were studied. The equal channel angular pressing process was carried out at room temperature by route C (sample rotation around the axis about 180° after each pass) in a die with two channels intersecting at an angle of Φp = 90. The softening mechanism through dynamic recovery was recognized up to 6th equal channel angular pressing pass, however, after that the mechanical strengthening was revealed. The samples after equal channel angular pressing processing were annealed in different temperature and time conditions. The influence of annealing temperature and time on microhardness as well as diameter of grain size were investigated in samples processed by the 4th equal channel angular pressing pass.
Źródło:
Acta Physica Polonica A; 2012, 122, 3; 557-560
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Occurrence of antibodies against Chlamydophila abortus in sheep and goats in the Slovak Republic
Autorzy:
Cislakova, L
Halanova, M.
Kovacova, D.
Stefancikova, A.
Powiązania:
https://bibliotekanauki.pl/articles/51528.pdf
Data publikacji:
2007
Wydawca:
Instytut Medycyny Wsi
Tematy:
goat
Chlamydophila abortus
sheep
Slovak Republic
serological examination
occurrence
antibody
Opis:
Chlamydophila abortus is one of the most important causative agents of enzootic abortion and other chlamydial infections of sheep and goats. The presence of specifi c serum antibodies to Chlamydophila abortus was studied in sheep and goats breeding in the Slovak Republic by the complement fi xation test. 22,040 sheep and goats were examined during 5 years. Specifi c anti-Ch. abortus antibodies were found in 2,360 out of 20,878 sheep sera examined (11.7%), and in 85 out of 1,162 examined goats (7.7%). The occurrence of antichlamydial antibodies indicates the importance of performing screening examinations in commercial breeding with the aim of reducing the spread of this disease between animals, and also interrupting the spread and transmission from animals to human.
Źródło:
Annals of Agricultural and Environmental Medicine; 2007, 14, 2
1232-1966
Pojawia się w:
Annals of Agricultural and Environmental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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