K.J. Kurzydlowski

Warsaw University of Technology, Warszawa, Masovian Voivodeship, Poland

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Publications (150)145.23 Total impact

  • P. Maj, J. Zdunek, J. Mizera, K.J. Kurzydlowski
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    ABSTRACT: The aim of this research was to investigate the influence of a geometrical notch on the Portevin–Le Chatelier effect. This phenomenon manifests itself as the serrated stress–strain curve obtained for certain materials when they undergo plastic deformation during tensile tests. The Portevin–Le Chatelier effect can often be observed in aluminum alloys especially those with an addition of magnesium. The material examined in the present experiments was a model Al–3Mg alloy. Samples were prepared with notches cut in the specimens with different depths and shapes. The results clearly indicate that the notch has a significant influence on the Portevin–Le Chatelier effect. With increasing notch depth, the stress amplitude of the serrations increases together with their frequency and the course of the serrations changes.
    Materials Characterization 10/2014; 96:46–53. · 1.88 Impact Factor
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    ABSTRACT: Corrosion behavior of a metallic biomaterial is an important characteristic because the biocompatibility of a biomedical grade metallic implant is primarily related to corrosion behavior. The aim of this research was to study the effect of Equal Channel Angular Pressing (ECAP) process on corrosion behavior of the AISI 316L type austenitic stainless steel. ECAP was conducted on an AISI 316L stainless steel up to eight passes. Scanning transmission electron microscopy (STEM) technique was utilized to study the microstructure of the as-received material and the samples subjected to ECAP. Electrochemical corrosion polarization and electrochemical impedance spectroscopy tests were performed in Ringer solution in order to determine and compare the corrosion behavior of initial coarse-grained and ECAP-ed specimens as an indication of biocompatibility. The results showed that an ultrafine-grained/ nanocrystalline 316L stainless steel with a mean grain size of about 78 nm was obtained after performing the eight passes of ECAP. The corrosion resistance of 316L stainless steel was improved considerably by increasing of the number of ECAP passes. After performing the eight passes of ECAP process, the corrosion rate of 316L stainless steel measured to be 0.42 μA.cm2 which is significantly lower than that of initial coarse-grained material (3.12 μA.cm2).
    Corrosion -Houston Tx- 09/2014; · 1.77 Impact Factor
  • W. Chrominski, M. Kulczyk, M. Lewandowska, K.J. Kurzydlowski
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    ABSTRACT: Precipitation strengthening of an ultrafine-grained Al-Mg-Si alloy has been studied using samples obtained by hydrostatic extrusion. It has been demonstrated that the microstructure after hydrostatic extrusion consists of two types of grains: (1) nano-sized free of dislocations and surrounded with high angle grain boundaries and (2) micron-sized with dislocation substructure. After ageing at 160 °C, small needle-like precipitates appear in grain interiors of both nano- and micron-sized grains, bringing about a significant strength improvement. However, the precipitates are smaller than those in their coarse grained counterparts. As a consequence, they constitute weaker barriers for dislocations and induce a lower strengthening effect. In addition, one may observe intensive precipitation at nano-grains boundaries, which further reduces the strengthening effect. It was also shown that peak ageing and overageing take place for much shorter time than in the case of coarse grained samples and are caused by the grain growth rather than a change in the precipitation state.
    Materials Science and Engineering A 07/2014; 609:80–87. · 2.41 Impact Factor
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    ABSTRACT: The precipitation phenomena in 7475 nanograined aluminium alloy was analysed by means of microhardness measurements, small angle X-ray scattering and electron microscopy. The nanograined samples were obtained by the hydrostatic extrusion of solution annealed and water quenched samples. It has been established that low temperature ageing causes precipitation processes to occur. However, the precipitation phenomena in nanograined materials proceed differently to those in micrograined materials. Moreover, the particle strengthening is limited by enhanced grain boundary precipitation which does not contribute to an increase in strength (when dislocation slip is the dominant deformation mechanism) and by the smaller size of precipitates.
    Advanced Engineering Materials 04/2014; · 1.61 Impact Factor
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    ABSTRACT: Equal channel angular pressing (ECAP) CP-Ti Ultrafine-grained materials Corrosion resistance Cell behavior The electrochemical and cellular behavior of commercially pure titanium (CP-Ti) with both ultrafine-grained (UFG) and coarse-grained (CG) microstructure was evaluated in this study. Equal channel angular pressing was used to produce the UFG structure titanium. Polarization and electrochemical impedance tests were carried out in a simulated body fluid (SBF) at 37 °C. Cellular behaviors of samples were assessed using fibroblast cells. Results of the investigations illustrate the improvement of both corrosion and biological behavior of UFG CP-Ti in comparison with the CG counterpart.
    Materials Science and Engineering C 03/2014; · 2.74 Impact Factor
  • Marcin K. Heljak, Wojciech Swieszkowski, Krzysztof Jan Kurzydlowski
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    ABSTRACT: The rate of hydrolytic degradation of tissue-engineered scaffolds made from bioresorbable polyesters is dependent on several factors. Some are related to the properties of the degrading polymeric material, but others are related to the geometry of the porous structure and the operating environment. It is well known that the rate of hydrolytic degradation of a given object, porous or nonporous, is lower when it is exposed to dynamic conditions, a flowing medium, than when it operates in static conditions. The most likely reason is the more efficient removal of the acidic degradation products from the vicinity of the polymeric material when it is operating in a flowing medium. In this article, we present a new phenomenological reaction–diffusion model of aliphatic polymer degradation. The model can be used to predict the significance of various factors in in vitro degradation tests, with particular reference to the flow of the degradation medium, and the frequency of medium replacement in the case of static conditions. The developed model was used to simulate the degradation of poly(dl-lactide-co-glycolide) scaffolds with different porosities subjected to static and dynamic testing conditions. The results confirm that the porosity of the scaffold had a significant influence on the degradation rate. It was shown that the combination of dynamic conditions and high porosity effectively reduced the mass loss and molecular weight loss of the degrading polymer. However, the effect of changes in the velocity of the flowing medium had a negligible effect on the rate of degradation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40280.
    Journal of Applied Polymer Science 01/2014; · 1.40 Impact Factor
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    ABSTRACT: Nerve tissue engineering (TE) is a rapidly expanding area of research advancing towards the repair and regeneration of non-union peripheral nerve defects caused by injuries. The current challenge for researchers is to develop a biomimetic scaffold that is capable of stimulating the re-growth of the native tissue, thus structurally mimicking the extracellular matrix (ECM), providing chemical guidance cues and mechanical support for re-enervation of the damaged region. Laminin is a glycoprotein naturally occurring in nerves and it plays a significant role towards the migration of nerve cells and axonal outgrowth. In this study, laminin incorporated scaffolds were produced by co-axial electrospinning and blend electrospinning techniques, in order to develop suitable biomaterial constructs for peripheral nerve tissue regeneration. Core–shell and blend nanofibers of laminin incorporated poly(L-lactic acid)-co-poly(ε-caprolactone) (PLCL) with diameters of 316 ± 110 nm and 350 ± 112 nm were respectively, fabricated and the morphology, surface hydrophilicity, chemical and mechanical properties were investigated. The ability of attachment and proliferation of Schwann cells on the electrospun nanofibrous scaffolds was investigated by cell proliferation assay and their phenotype was evaluated by immunocytochemical staining using specific S100 antibody. The cells were found to attach and proliferate on core–shell PLCL–laminin scaffolds, expressing bi- and tri-polar elongations retaining their typical phenotype. Results of 7 days of in vitro culture of Schwann cells, showed 78% increase in cell proliferation on core–shell structured nanofibers compared to blend PLCL–laminin scaffolds, which confirmed the potential application of these constructs as substrates for peripheral nerve regeneration.
    European Polymer Journal 01/2014; 50:30–38. · 3.24 Impact Factor
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    ABSTRACT: Fabrication of scaffolds for tissue engineering (TE) applications becomes a very important research topic in present days. The aim of the study was to create and evaluate a hybrid polymeric 3D scaffold consisted of nano and microfibers, which could be used for bone tissue engineering. Hybrid structures were fabricated using rapid prototyping (RP) and electrospinning (ES) methods. Electrospun nanofibrous mats were incorporated between the microfibrous layers produced by RP technology. The nanofibers were made of poly(L-lactid) and polycaprolactone was used to fabricate microfibers. The micro- and nanostructures of the hybrid scaffolds were examined using scanning electron microscopy (SEM). X-ray microtomographical (μCT) analysis and the mechanical testing of the porous hybrid structures were performed using SkyScan 1172 machine, equipped with a material testing stage. The scanning electron microscopy and micro-tomography analyses showed that obtained scaffolds are hybrid nanofibers/microfibers structures with high porosity and interconnected pores ranging from 10 to 500um. Although, connection between microfibrous layers and electrospun mats remained consistent under compression tests, addition of the nanofibrous mats affected the mechanical properties of the scaffold, particularly its elastic modulus. The results of the biocompatibility tests did not show any cytotoxic effects and no fibroblast after contact with the scaffold showed any damage of the cell body, the cells had proper morphologies and showed good proliferation. Summarizing, using RP technology and electrospinning method it is possible to fabricate biocompatible scaffolds with controllable geometrical parameters and good mechanical properties.
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    P. Maj, J. Zdunek, M. Gizynski, J. Mizera, K.J. Kurzydlowski
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    ABSTRACT: The Portevin–Le Chatelier effect manifests itself as an unstable plastic flow which occurs during tensile tests of some dilute materials in a certain range of temperatures and strain rates. This phenomenon is also exceptionally intense in nickel based superalloys used in the aerospace industry. The aim of this research was to investigate the Portevin–Le Chatelier effect in Inconel 718 solution strengthened superalloy. The tested material was subjected to tensile tests carried out within the temperature range 250–600 °C with three different strain rates 2×10−3 s−1, 10−2 s−1 and 5×10−2 s−1. The strain curves were analyzed in terms of intensity and statistical behavior. A quantitative method to describe the phenomenon was used in the study. The results indicate the presence of clear trends with temperature and strain rates. Additional optical observations were carried out to assess the changes of the microstructure.
    Materials Science and Engineering: A. 01/2014; 619:158–164.
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    ABSTRACT: This study concerns imaging of the structure of materials using AFM tapping (TM) and phase imaging (PI) mode, using probes modified with Focused Ion Beam (FIB). Three kinds of modifications were applied–thinning of the cantilever, sharpening of the tip and combination of these two modifications. Probes shaped in that way were used for AFM investigations with Bruker AFM Nanoscope 8. As a testing material, titanium roughness standard supplied by Bruker was used. The results show that performed modifications influence the oscillation of the probes. In particular thinning of the cantilever enables one to acquire higher self-resonant frequencies, which can be advantageous for improving the quality of imaging in PI mode. It was found that sharpening the tip improves imaging resolution in tapping mode, which is consistent with existing knowledge, but lowered the quality of high frequency topography images. In this paper the Finite Element Method (FEM) was used to explain the results obtained experimentally.
    Micron. 01/2014;
  • Tomasz Brynk, Zbigniew Pakiela, Mariusz Kulczyk, Krzysztof J. Kurzydlowski
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    ABSTRACT: Fatigue crack growth tests are performed to determine materials service life using standardized geometry of samples and test procedures, which are difficult to fulfill in the case of ultrafine-grained metals, such as obtained by hydro-extrusion. This calls for the use of mini-samples. However, mini-samples require a special approach to displacement measurements. The aim of the present study was to demonstrate the possibility of fatigue crack growth rate tests with mini-samples made of Al 5483 and 7475 alloys in as delivered states and subjected to the grain size refinement by hydro-extrusion. The optical Digital Image Correlation, DIC, was used to this end. The results of the measurements were transformed into maps of displacements near to the crack tip registered at the maximum load for pre-selected loading cycles. The displacement fields were subsequently used to determine stress intensity factor values, positions of the crack tip and to develop Paris plots. The results allowed to compare fatigue crack growth rates in standard and ultrafine-grained aluminum alloys.
    Mechanics of Materials 12/2013; 67:46–52. · 2.23 Impact Factor
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    ABSTRACT: In the reported work, the combination of severe plastic deformation (SPD) and annealing under high hydrostatic pressure was used to enhance the ductility whilst maintaining the high mechanical strength possessed by the nanostructured 316LVM stainless steel. The nanostructure was obtained by a multi-step hydrostatic extrusion process to a total true strain of 1.8. This process produced a microstructure consisting of nanotwins and shear bands. The extruded samples were annealed at 700 and 900 °C for 10 min under atmospheric or hydrostatic pressures of 2 or 6 GPa. The resulting microstructures were examined using TEM and FIB techniques. The microstructural observations and X-ray measurements were used to estimate the crystallite sizes. The mechanical properties were determined by microhardness and tensile tests. It was established that annealing under high pressure improved the ductility of the material whilst retaining its high ultimate tensile strength.
    Mechanics of Materials 12/2013; 67:25–32. · 2.23 Impact Factor
  • Materials. 11/2013; 6(11):5016-5037.
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    ABSTRACT: In this work, the effects of vanadium addition in the range of 0.3-3% (in weight percent) for an oxide dispersion strengthened reduced activation ferritic (ODS RAF) steel were investigated. Samples of the V-modified steel have been prepared using elemental (Fe, Cr, W, Ti) and Y2O3 powders with the nominal composition of Fe-14Cr-2W-0.3Ti-0.3Y2O3. Consolidated and heat treated samples were investigated using Scanning Electron Microscopy and Scanning Transmission Electron Microscopy equipped with Electron Energy Loss Spectroscopy detector. Hardness and Charpy impact tests (KLST specimens) were also performed. The microstructure investigations revealed numerous particles of the size up to 0.5 μm. They are primarily Ti-Cr-V oxides located at the grain boundaries and inside the grains. These particles increase hardness and significantly reduce fracture resistance of the ODS RAF alloys developed here. However, it should be noted that the 0.3% V-ODS steel has unexpectedly the lowest transition temperature of about 282 K and that the 1-3% V-ODS steels, in spite of the transition temperature about 373 K, exhibit almost two times higher the lower shelf energy values in comparison with the 0.3% V-ODS and 0% V-ODS steels.
    Journal of Nuclear Materials 11/2013; 442(1-3). · 2.02 Impact Factor
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    ABSTRACT: In this study, the stability of grain size and oxide nanoparticles in the ODS steel upon annealing at high temperature (650–1350 °C) has been evaluated. The ODS Fe–Cr–W–Ti–Y2O3 steel has been manufactured by powder metallurgy, consolidated by hot isostatic pressing and processed by hydrostatic extrusion. Such a processing brings about ultrafine grain structure reinforced with oxide nanoparticles (few nm in diameter) and results in superior mechanical properties. The stability of nano-oxides has been analyzed by small angle X-ray scattering together with transmission electron microscopy. The results obtained revealed excellent thermal stability of ultrafine grained ODS ferritic steel, which was attributed to the resistance of oxides against coarsening.
    Journal of Materials Science 07/2013; 48(13):4620-4625. · 2.31 Impact Factor
  • Journal of Nanoscience and Nanotechnology 06/2013; 13(6):4025. · 1.15 Impact Factor
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    ABSTRACT: In the present study, the high pressure torsion (HPT) was used to refine the grain structure down to the nanometer scale in an austenitic stainless steel. The principles of HPT lay on torsional deformation under simultaneous high pressure of the specimen, which results in substantial reduction in the grain size. Disks of the 316LVM austenitic stainless steel of 10 mm in diameter were subjected to equivalent strains epsilon of 32 at RT and 450 degrees C under the pressure of 4 GPa. Furthermore, two-stage HPT processes, i.e., deformation at room temperature followed by deformation at 450 degrees C, were performed. The resulting microstructures were investigated in TEM observations. The mechanical properties were measured in terms of the microhardness and in tensile tests. HPT performed at two-stage conditions (firstly at RT next at 450 degrees C) gives similar values of microhardness to the ones obtained after deforming only at 450 degrees C but performed to higher values of the overall equivalent strain epsilon. The effect of high pressure torsion on structural refinement and mechanical properties of an austenitic stainless steel was evaluated.
    Journal of Nanoscience and Nanotechnology 05/2013; 13(5):3246-9. · 1.15 Impact Factor
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    M. Rasinski, H. Maier, C. Ruset, M. Lewandowska, K. J. Kurzydlowski
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    ABSTRACT: Tungsten coatings with molybdenum interlayer deposited on carbon-fibre reinforced carbon (CFC) substrates were selected as the first wall material for the divertor in the Wall Project at Joint European Torus (similar to the International Thermonuclear Experimental Reactor). For such a layered structure, diffusion of carbon from the CFC substrate towards the Mo and W deposits is expected during the operation of the reactor. As both molybdenum and tungsten form stable carbides, brittle compounds may form at the interface, thus strongly affecting the thermomechanical performance of the coated tiles. For the purpose of prediction of the operation time of such coated tiles, carbon diffusion and carbide formation kinetics need to be determined. In the present study, W/Mo/CFC samples were subjected to heat treatment at 1470 K for various annealing times. The Focused Ion Beam technique was used for sample preparation for electron microscopy examinations. Transmission electron microscopy observations supported with diffraction pattern analyses revealed the both W2C and WC carbides in the W coating, as well as that of Mo2C carbide in the Mo layer. The results were used to estimate the kinetics of coatings degradation.
    Thin Solid Films 03/2013; 531:21-25. · 1.87 Impact Factor
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    ABSTRACT: The plasma facing components (PFCs) must withstand the thermal, mechanical and neutron loads under cyclic mode of operation and vacuum. Despite that PFCs of ITER and demonstration reactors must assure reliability and long in service lifetime. For that reason PFCs are designed to be made of beryllium, tungsten or carbon fibre composites armours and copper based heat sink material. Such design concepts can only be used if joining methods of these dissimilar materials are resolved. Several techniques have been developed for joining W and Cu e. g. casting of pure Cu onto W, high temperature brazing, direct diffusion bonding or CVDs of W onto Cu. The main problem in the development of such joints is the large difference in the coefficients of thermal expansion, CTE (alphaCu4alphaW) and elastic modula (ECu0.2EW). These differences result in large stresses at the W/Cu interfaces during manufacturing and/or during operation, which may lead to cracking or delamination reducing lifetime of the components. Possible solution to this problem is the use of W-Cu composites (FGM). W-Cu composites are widely used for spark erosion electrodes, in heavy duty circuit breakers and as heat sinks of microelectronic devices. They are commonly produced by infiltration of a porous sintered tungsten by liquid copper. Other technological route is powder metallurgy. Coatings can be produced by low pressure plasma spraying. All these methods, however, are known to have some disadvantages. For infiltration there is a 30 wt.% limit of Cu content while for powder metallurgy and plasma spraying techniques porosity is of concern. In our work the W-Cu composites of different composition were produced by pulse plasma sintering (PPS). This new method utilizes pulsed high electric discharges to heat the powders under uniaxial load. The arc discharges clean surface of powder particles and intensify diffusion. The total sintering time is reduced to several minutes. In our investigations various conditions of milling, mixing and sintering have been examined. The chemistry and microstructure of powders and composites were investigated. Mechanical properties were measured at room temperature in tensile tests (microsamples) and by hardness measurements. Measurements of coefficients of thermal expansion were also carried out. It has been found that PPS method can be used to obtain material of 98% TD. The experiments of joining the composite material to tungsten and copper plates gave promising results.
    24th Symposium on Fusion Technology; 03/2013
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    ABSTRACT: The rapidly advancing miniaturization of micro-electronic devices leads to a considerable increase of the amount of heat evolved by electronic circuits. This, combined with the inexorable increase in the clock speed of running such devices, results in skyrocketing power densities in modern devices such as micropro-cessors and other high-performance chips. It is anticipated that, in the current decade, the power density will reach the limiting value possible to dissipate by the materials used at the present. As predicted by Patrick Gelsinger (Intel CTO), during the next few years the semiconductor industry will be "heating to a meltdown", with the trend of power densities in modern microprocessors literally escalating toward levels found within a nuclear reactor. In order to enable the packing density of micro-electronic devices to be further increased, we need new materials of higher thermal conductivity. Another requirement is that these materials should have a thermal expansion coefficient comparable with that of the microelectronic substrate material so as to avoid damage to the heat sink/substrate joint due to the thermal stresses induced by cyclic temperature variation. These requirements can be satisfied by the diamond/metal composites with the metal matrix of high thermal conductivity, such as e.g. Cu. The thermal properties (conductivity, thermal expansion) of the composites can easily be tailored by modifying the metal/diamond proportion. However, within the temperature range of consolidation of these composites, diamond is a metastable phase and may, during the consolidation, be transformed into its stable phase i.e. graphite. This can be avoided by conducting the process under conditions of thermodynamic stability of diamond, i.e. by applying appropriately high consolidation pressure (4–5 GPa), which however increases the production costs. The authors of the present study experimented with producing copper/diamond composites with 50 vol.% of diamond particles under conditions of thermodynamic instability of diamond by consolidating the composite using the pulse plasma sintering (PPS) method. The process temperature was 900 °C, the pressure was 80 MPa and the sintering time was 10 min. The phase composition, density and microstructure of the composites thus obtained were examined. The Cu/diamond PPS-consolidated composites had a theoretical density of 96% and the diamond particles were distributed uniformly within the copper matrix. The major challenge in the development of this kind of composites is to obtain a well bonded interface between the copper and the diamond. To increase the interfacial bonding in the Cu/diamond composites the copper was alloyed with chromium to form Cu0.8Cr. The Cu0.8Cr/diamond composite had a theoretical density of 99.8% and was characterized by a strong bond between the diamond and the copper matrix, which was due to formation the interface between diamond and copper matrix. This paper presents the results of TEM examinations of this interface and describes the method of preparation of thin foils cut through it using a FIB technique.
    Diamond and Related Materials 03/2013; 27-28:29-35. · 1.71 Impact Factor

Publication Stats

260 Citations
145.23 Total Impact Points


  • 1984–2014
    • Warsaw University of Technology
      • Faculty of Materials Science and Engineering
      Warszawa, Masovian Voivodeship, Poland
  • 2010
    • Queensland University of Technology
      • Institute of Health and Biomedical Innovation
      Brisbane, Queensland, Australia
  • 1986–1991
    • University of Manitoba
      • • Department of Mechanical and Manufacturing Engineering
      • • Faculty of Engineering
      Winnipeg, Manitoba, Canada
  • 1987–1988
    • The University of Winnipeg
      Winnipeg, Manitoba, Canada