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Artifacts and errors in EBSD mapping of retained austenite in TRIP steel
Mikmeková, Šárka; Jozefovič, Patrik; Ambrož, Ondřej
2021 - English
The present work aims to demonstrate artifacts and errors in visualization of retained austenite phase in TRIP steel by an electron back-scattered diffraction (EBSD) technique. Retained austenite phases size and shape obtained by the EBSD are directly compared with a real image of these phases acquired by means of an atomic force microscopy (AFM). The effect of the step size parameter used for the EBSD analysis on the retained austenite phase fraction and morphology is discussed in detail and quantified. Surface roughness as a barrier for the imaging of fine features situated on a specimen surface is demonstrated.
Keywords:
EBSD; SEM; AFM; retained austenite; TRIP steel
Available at various institutes of the ASCR
Artifacts and errors in EBSD mapping of retained austenite in TRIP steel
The present work aims to demonstrate artifacts and errors in visualization of retained austenite phase in TRIP steel by an electron back-scattered diffraction (EBSD) technique. Retained austenite ...
Adhesion of PVD Coatings on Surface of Small Arm
Joska, Z.; Rak, L.; Daniel, Josef; Horníček, J.; Tříska, V.; Nguyen, C.H.
2020 - English
This work deals with the possibility of increasing the utility properties of the functional part of the weapon by deposition of PVD coating. These coatings are widely known for their high hardness and abrasion resistance without affecting the anticorrosion properties. The experimental part evaluates the created duplex coating on the piston of the assault rifle Sa vz. 58. Duplex coating adhesion, surface morphology and coating thickness was evaluated on opto digital microscope Olympus DSX 500. The impact resistance of the coating was evaluated by dynamic impact test. The durability tests of the coatings were carried out during the training of students in the military training. The results showed the application of PVD coating significantly reduced piston head wear and increased user comfort in the form of shortening time of the cleaning and maintenance process after firing.
Keywords:
adhesion of PVD Coatings
Available at various institutes of the ASCR
Adhesion of PVD Coatings on Surface of Small Arm
This work deals with the possibility of increasing the utility properties of the functional part of the weapon by deposition of PVD coating. These coatings are widely known for their high hardness and ...
Trip steel specimen preparation for advanced sem and EBSD
Ambrož, Ondřej; Mikmeková, Šárka; Hegrová, J.; Aoyama, T.
2020 - English
Modern scanning electron microscopy (SEM) allows observations of specimens with high surface sensitivity. The surface sensitivity is significantly affected by the accelerating voltages. With the development of the scanning electron microscopy, the requirements for the surface quality of samples increase. Metallographic methods originally intended for light microscopy become insufficient. The problem occurs especially with multiphase materials having a fine-grained structure. The investigated TRIP steel consists of a ferritic-bainitic matrix, retained austenite and martensite phases. The sizes of the smallest phases are nanometer units. The volume of residual austenite was determined by X-ray diffraction. The basic preparation of all tested samples involved conventional metallographic grinding and very fine mechanical polishing. One sample was analysed in this state. Other samples were subsequently chemically polished, electropolished and chemical-mechanically polished. The specimens were observed in the SEM using a SE and a BSE detector at low energies immediately after the preparation. An EBSD was performed in the same areas to characterize the retained austenite. Topographical imaging by special AFM, integrated into the SEM, demonstrated that the mechanical polishing results in surface deformation and residual austenite is transformed. All other methods have their specifics and for modern sensitive SEM instruments it is necessary to optimize individual procedures.
Keywords:
TRIP steel; metallography; SEM; EBSD; AFM
Available at various institutes of the ASCR
Trip steel specimen preparation for advanced sem and EBSD
Modern scanning electron microscopy (SEM) allows observations of specimens with high surface sensitivity. The surface sensitivity is significantly affected by the accelerating voltages. With the ...
Dynamic impact wear and impact resistance of W-B-C coatings
Daniel, Josef; Grossman, Jan; Buršíková, V.; Zábranský, L.; Souček, P.; Mirzaei, S.; Vašina, P.
2020 - English
Coated components used in industry are often exposed to repetitive dynamic impact load. The dynamic impact test is a suitable method for the study of thin protective coatings under such conditions. Aim of this paper is to describe the method of dynamic impact testing and the novel concepts of evaluation of the impact test results, such as the impact resistance and the impact deformation rate. All of the presented results were obtained by testing two W-B-C coatings with different C/W ratio. Different impact test results are discussed with respect to the coatings microstructure, the chemical and phase composition, and the mechanical properties. It is shown that coating adhesion to the HSS substrate played a crucial role in the coatings.
Keywords:
boron carbide W-B-C; fracture resistance; impact wear; W-B-C
Available at various institutes of the ASCR
Dynamic impact wear and impact resistance of W-B-C coatings
Coated components used in industry are often exposed to repetitive dynamic impact load. The dynamic impact test is a suitable method for the study of thin protective coatings under such conditions. ...
Study of secondary phases in trip steel by advanced sem and afm techniques
Mikmeková, Šárka; Ambrož, Ondřej; Hegrová, J.; Aoyama, T.
2020 - English
The paper aims to demonstrate a modern scanning electron microscope (SEM) as a powerful tool for visualization of the secondary phases in TRIP steel. The TRIP steel specimens prepared by various metallographic techniques were imaged by the SEM and the secondary phases presence was confirmed by an electron back-scattered diffraction (EBSD) technique. The chemical polishing by 5 % HF in H2O2 for 10 seconds results in selective etching for each individual phase, as confirmed by an atomic force microscopy (AFM) and hybrid AFM-in-SEM techniques. The phases are easily distinguishable in the SEM micrographs created by the low energy high take-off angle signal electrons. The proposed sample preparation technique together with special SEM imaging conditions enables us accurate analysis of distribution of secondary phases within the TRIP steel matrix and moreover, the retained austenite is distinguishable from the martensite phase.
Keywords:
TRIP steel; advanced SEM; metallography
Available at various institutes of the ASCR
Study of secondary phases in trip steel by advanced sem and afm techniques
The paper aims to demonstrate a modern scanning electron microscope (SEM) as a powerful tool for visualization of the secondary phases in TRIP steel. The TRIP steel specimens prepared by various ...
Determination of thickness refinement using STEM detector segments
Skoupý, Radim; Krzyžánek, Vladislav
2019 - English
Quantitative STEM imaging together with Monte Carlo simulations of electron scattering in solids can bring interesting results about properties of many thin samples. It is possible to determine thickness of a sample, to calculate mass of particles and measure mass per length/area. Appropriate calibration is one of the crucial parts of the method. Even a small error or inaccuracy in detector response to electron beam either blanked or full brings significant error into thickness determination. This problem can be overcome by parallel STEM imaging in more segments of the detector. Comparing more segments gives a possibility to use a signal from different segments for different thicknesses of a sample. Accuracy of individual parts of the detector depends on the captured signal quantity. It is desirable to use such a STEM detector segment that provides the greatest signal change to a unit of thickness. To demonstrate the usage, we used a sample of Latex nanospheres placed on thin carbon lacey film, diameter of the nanospheres was around 600 nm in order to compare the results from different detector segments. Thanks to the known thickness of the sample (calculated from its geometrical shape), it is possible to estimate the optimal acquisition settings and post processing steps with the known and the true state of the sample.
Keywords:
electron-microscopy; Quantitative STEM; thickness determination; detector segments; Monte Carlo simulation
Available at various institutes of the ASCR
Determination of thickness refinement using STEM detector segments
Quantitative STEM imaging together with Monte Carlo simulations of electron scattering in solids can bring interesting results about properties of many thin samples. It is possible to determine ...
An appropriate method for assessing hydrogel pore sizes by cryo-sem
Adámková, Kateřina; Trudicová, M.; Hrubanová, Kamila; Sedláček, P.; Krzyžánek, Vladislav
2019 - English
The aim of our work was to examine and describe ultrastructure of the agarose hydrogel and any possible structural concentration dependencies, and to assess the distribution and size of pores of agarose hydrogel in dependence on its concentration. Four concentrations were prepared (0.5 %, 1.0 %, 2.0 % and 4.0 % of dry weight content) and cryo-SEM and turbidimetry methods were executed on wet (original) samples in order to image the ultrastructure and measure the pore sizes within. \nReasonable results were obtained for the wet samples as they were closer to their native state they are usually used for applications in. Cryo-SEM and turbidimetry provided comparable results of pore diameters and allowed to compare pore diameters dependant on the concentrations, moreover, it showed more detailed and realistic structure.
Keywords:
hydrogelcryo-SEM; agarose; cryo-SEM; freezing methods; image analysis
Available at various institutes of the ASCR
An appropriate method for assessing hydrogel pore sizes by cryo-sem
The aim of our work was to examine and describe ultrastructure of the agarose hydrogel and any possible structural concentration dependencies, and to assess the distribution and size of pores of ...
Hiding e-beam exposure fields by deterministic 2D pattering
Horáček, Miroslav; Knápek, Alexandr; Matějka, Milan; Krátký, Stanislav; Urbánek, M.; Mika, Filip; Kolařík, Vladimír
2018 - English
The high stability and good current homogeneity in the spot of the e-beam writer is crucial to\nthe exposure quality, particularly in the case of large-area structures when gray-scale\nlithography is used. Even though the deflection field distortion is calibrated regularly and\nbeam focus and beam astigmatism is dynamically corrected over the entire deflection field, we can observe disturbances in the exposed relief.\nRecently, we presented a method that makes use of e–beam exposure imperfection by\nintroducing marginally visible high–frequency diffraction gratings of variable pitch that fill in\nseparate orthogonal exposure fields. The actually presented approach follows up our\nresearch on aperiodic arrangements of optical primitives, especially on the phyllotactic–\nlike arrangement of sub–micron relief optical elements. This approach is extended from the\ndiffraction element arrangement to the higher level of exposure fields arrangements.
Keywords:
phyllotaxis; electron beam lithography
Available at various institutes of the ASCR
Hiding e-beam exposure fields by deterministic 2D pattering
The high stability and good current homogeneity in the spot of the e-beam writer is crucial to\nthe exposure quality, particularly in the case of large-area structures when gray-scale\nlithography is ...
STEM modes in SEM
Konvalina, Ivo; Paták, Aleš; Mikmeková, Eliška; Mika, Filip; Müllerová, Ilona
2018 - English
The segmented semiconductor STEM detector in the Magellan 400 FEG SEM microscope\n(https://www.fei.com/) is used to detect transmitted electrons (TEs) and allows observing\nsamples in four imaging modes. Two modes of objective lens, namely high resolution (HR)\nand ultra-high resolution (UHR), differ by their resolution and by the presence or absence of\na magnetic field around the sample. If the beam deceleration (BD) mode is chosen, then\nan electrostatic field around the sample is added and two further microscope modes HR + BD\nand UHR + BD, become available. Trajectories of TEs are studied with regard to their angular\nand energy distribution in each mode in this work.\n
Keywords:
SEM; STEM
Available at various institutes of the ASCR
STEM modes in SEM
The segmented semiconductor STEM detector in the Magellan 400 FEG SEM microscope\n(https://www.fei.com/) is used to detect transmitted electrons (TEs) and allows observing\nsamples in four imaging ...
Creation of electron vortex beams using the holographic reconstruction method in a scanning electron microscope
Řiháček, Tomáš; Horák, M.; Schachinger, T.; Matějka, Milan; Mika, Filip; Müllerová, Ilona
2018 - English
Electron vortex beams (EVB) were theoretically predicted in 2007 and first experimentally\ncreated in 2010. Although they attracted attention of many researchers, their\ninvestigation takes place almost solely in connection with transmission electron microscopes (TEM). On the other hand, although scanning electron microscopes (SEM) may provide some advantages for EVB applications, only little attention has been dedicated to them. Therefore, the aim of this work is to create electron vortices in SEM at energies of several keV.
Keywords:
electron vortex beams; scanning electron microscopy; electron diffraction
Available at various institutes of the ASCR
Creation of electron vortex beams using the holographic reconstruction method in a scanning electron microscope
Electron vortex beams (EVB) were theoretically predicted in 2007 and first experimentally\ncreated in 2010. Although they attracted attention of many researchers, their\ninvestigation takes place ...
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