Ivo Šulák
Academy of Sciences of the Czech Republic
Cubic zirconiaCeramicCrystalliteTransmission electron microscopyStrain rateLüders bandComposite materialFocused ion beamThermal barrier coatingEutectic systemHardening (metallurgy)MetallurgyMaterials scienceSuperalloyScanning electron microscopeInconelLow-cycle fatigueSofteningCoatingSlip (materials science)Atmospheric-pressure plasmaMicrostructureYttria-stabilized zirconia
23Publications
5H-index
73Citations
Publications 22
Newest
#1Talha J. Pirzada (University of Oxford)H-Index: 3
#2Dong Liu (UoB: University of Bristol)H-Index: 13
Last. Robert O. Ritchie (University of California, Berkeley)H-Index: 132
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Abstract The deformation and fracture of a 0/90 °Nextel 720 alumina/Mullite fibre / alumina matrix ceramic-matrix composite material has been observed by in situ synchrotron x-ray computed micro-tomography at ambient temperature and at 1100 °C. A three-point loading configuration was used and samples were loaded monotonically until final fracture. The flexural strength was found to be unaffected by temperature. 3D visualisation of the microstructure showed fracture occurred by propagation of int...
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#1Stanislava Fintová (CAS: Academy of Sciences of the Czech Republic)H-Index: 12
#2Ivo Kuběna (CAS: Academy of Sciences of the Czech Republic)H-Index: 14
Last. Jaroslav Polák (CAS: Academy of Sciences of the Czech Republic)H-Index: 39
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Abstract Pure polycrystalline copper has been subjected to cyclic loading with frequencies from 4 Hz to 20 kHz. With increasing frequency, the S-N curve was shifted to a higher number of cycles to fracture. Quasi-static and dynamic tensile tests were performed to identify the strain rate sensitivity corresponding to the increase of the cyclic frequency in order to explain the shift of the S-N curve with the frequency. Surface relief evolution has been studied in specimens cycled with various str...
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Abstract null null Surface relief evolution and fatigue crack initiation of Rene 41 superalloy was studied. The material was tested in two thermodynamical states: solutionised and aged. Cylindrical specimens were cycled at total strain amplitude 0.8% at room temperature. In order to study relevant mechanisms resulting in surface relief formation and eventually fatigue crack initiation, cycling was interrupted at definite number of elapsed cycles. After each interruption, the specimen surface was...
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Superaustenitic steel Sanicro 25 has been subjected to in-phase and out-of-phase thermomechanical fatigue cycles in the temperature range from 250°C to 700°C. Both constant strain rate cycling and cycling with 10 minutes dwell at peak temperature were applied. The effect of the dwells on the cyclic response, internal structure and damage mechanism was studied. Cyclic hardening/softening curves, cyclic stress-strain curves and fatigue life curves were evaluated. The transmission electron microsco...
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#1Luca Bertolla (CAS: Academy of Sciences of the Czech Republic)H-Index: 1
#1Luca BertollaH-Index: 4
Last. Jiří Holas (Brno University of Technology)H-Index: 1
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Abstract We herein demonstrated the exfoliation of hexagonal boron nitride (h-BN) into nanosheets (BNNSs) by using concentrated low-modulus water glass (WG, SiO2/Na2O ratio = 1.6) as high viscosity exfoliating medium. The process led to BNNSs yield of nearly 30 %. As the suspension was neutralized with HCl, BNNSs with lateral size of approximately 250 nm and narrow size distribution, were found to align into perfectly parallel rows. High-resolution transmission electron microscopy (HR-TEM) analy...
1 CitationsSource
#1Ivo Šulák (CAS: Academy of Sciences of the Czech Republic)H-Index: 5
#2Karel Obrtlík (CAS: Academy of Sciences of the Czech Republic)H-Index: 20
Last. Ladislav Čelko (Central European Institute of Technology)H-Index: 11
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Abstract The charm of diffusion coatings is mainly in their protective function of the surface of gas turbine components, which are often subjected to fatigue-creep loading in extremely hostile environments. Their impact gains in importance with the increasing time that the components are exposed to high temperatures and aggressive environments. This motivates the authors to study the low cycle fatigue behaviour of Al-Cr coated nickel-based superalloy Inconel 713LC. Polycrystalline diffusion Al-...
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Abstract Cylindrical specimens of γ precipitate strengthened superalloy MAR-M247 were cyclically strained under total strain control conditions using a symmetrical push–pull cycle at 23 °C, 700 °C and 800 °C in air. The fatigue hardening/softening curves and low cycle fatigue life curves are presented. Special attention is paid to the effect of temperature on plastic strain localisation and fatigue crack initiation at 23 °C, 700 °C and 800 °C. Plastic strain localisation into dislocation-rich sl...
3 CitationsSource
#1Alice ChlupováH-Index: 1
#2Ivo ŠulákH-Index: 5
Last. Jiří SvobodaH-Index: 27
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The very recently developed coarse-grained new-generation oxide dispersion strengthened (ODS) alloys containing 5 vol.% homogeneously distributed yttrium nano-precipitates seems to be a promising oxidation-resistant structural material for applications at temperatures above 1000 °C. The primary aim of the present paper is the introduction of the new-generation oxide dispersion strengthened (ODS) alloy and the first testing of its high temperature fatigue properties at 800 °C, concurrently demons...
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#1Ivo Šulák (CAS: Academy of Sciences of the Czech Republic)H-Index: 5
#2Jiří Man (CAS: Academy of Sciences of the Czech Republic)H-Index: 19
Last. Karel Obrtlík (CAS: Academy of Sciences of the Czech Republic)H-Index: 20
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Abstract In the present work, the mechanisms of fatigue crack initiation and early crack propagation of a γ′ strengthened nickel-based superalloy have been investigated. Low cycle fatigue tests have been performed on polycrystalline superalloy MAR-M247 under symmetrical strain controlled loading at ambient temperature in air. The nature of early fatigue damage, crack initiation and subsequent fatigue crack propagation was assessed for applied total strain range of 1%. Test was interrupted at giv...
1 CitationsSource
#1Ivo Šulák (CAS: Academy of Sciences of the Czech Republic)H-Index: 5
#2Karel Obrtlík (CAS: Academy of Sciences of the Czech Republic)H-Index: 20
Last. David Jech (Central European Institute of Technology)H-Index: 5
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This study investigates the strain-controlled low-cycle fatigue (LCF) behaviour of an untreated and surface-treated MAR-M247 superalloy in a symmetrical push-pull cycle with a constant strain rate at 900°C in laboratory air. A newly developed experimental thermal and environmental barrier coating (TEBC) system, consisting of a 170 μm thick CoNiCrAlY bond coat (BC) and a bilayer ceramic top coat (TC), with an interlayer and an upper layer, was deposited using air plasma spray techniques. The cera...
1 CitationsSource