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Investigation of deformation mechanisms in textured magnesium alloy
Dittrich, J.; Čapek, J.; Knapek, Michal; Minárik, P.
2019 - English
Advanced in-situ and ex-situ methods were used to reveal active deformation mechanisms during deformation of magnesium alloy with a strong texture. Three sets of samples were prepared from the rolled sheet of commercial AZ31 alloy with respect to its strong basal texture - normal direction (ND), rolling direction (RD) and 45 degrees between RD and ND, and were deformed in both compression and tension. The signal of acoustic emission (AE) was measured concurrently during the deformation. Electron backscattered diffraction (EBSD) was used to study the microstructure after the selected stages of the deformation. It is shown that the extension twinning played an important role during the plastic deformation in the samples having favorably oriented basal texture component, whereas in the unfavorably oriented samples, the role of twinning was marginal. Pronounced activation of twinning only in some samples caused a considerable variation in the deformation behavior and AE response. A consistent link between the energy and amplitudes of the AE signal and the microstructure changes investigated by EBSD was established.
Keywords:
magnesium; deformation; twinning; acoustic emission; EBSD
Available at various institutes of the ASCR
Investigation of deformation mechanisms in textured magnesium alloy
Advanced in-situ and ex-situ methods were used to reveal active deformation mechanisms during deformation of magnesium alloy with a strong texture. Three sets of samples were prepared from the rolled ...
Effect of aluminum content and precipitation on the corrosion behavior and acoustic emission response of AZ31 and AZ80 magnesium alloys
Veverková, E.; Knapek, Michal; Minárik, P.
2019 - English
In this study, we investigated the effect of aluminum content and precipitation on the corrosion behavior of the AZ31 and AZ80 magnesium alloys. The investigated alloys were received in the as-extruded condition in order to retain comparable grain size and texture. First, solid solution treatment was performed on the samples of both alloys. Subsequently, the samples were isothermally aged at 200 degrees C for 20 hours. The scanning electron microscopy was used to study the grain size and microstructure. The corrosion properties of samples were studied by potentiodynamic polarization measurements and the AE signal was concurrently recorded. Solution treated AZ80 and AZ31 samples exhibited similar behavior. The aged AZ80 sample showed lower corrosion rate. Also, a strong breakdown appeared in the later (compared to other samples) stage of the potentiodynamic test. The breakdown was found to be easily recognized by AE parameters.
Keywords:
Magnesium alloys; corrosion; acoustic emission; polarization
Available at various institutes of the ASCR
Effect of aluminum content and precipitation on the corrosion behavior and acoustic emission response of AZ31 and AZ80 magnesium alloys
In this study, we investigated the effect of aluminum content and precipitation on the corrosion behavior of the AZ31 and AZ80 magnesium alloys. The investigated alloys were received in the ...
Effect of implantation of C, Si and Cu into ZrNb nanometric multilayers
Daghbouj, N.; Karlík, M.; Lorinčík, J.; Polcar, T.; Callisti, M.; Havránek, Vladimír
2019 - English
Sputter-deposited Zr/Nb nanometric multilayer films with a periodicity (L) in the range from 6 to 167 nm were subjected to carbon, silicon and copper ion irradiation with low and high fluences at room temperature. The ion profiles, mechanical proprieties, and disordering behavior have been investigated by using a variety of experimental techniques (Secondary Ion Mass Spectrometry - SIMS, nanoindentation, X-ray diffraction - XRD, and scanning transmission electron microscopy - STEM). On the STEM bright field micrographs there is damage clearly visible on the surface side of the multilayer. Deeper, the most damaged and disordered zone, located close to the maximum ion concentration, was observed. The in-depth C and Si concentration profiles obtained from SIMS were not affected by the periodicity of the nanolayers. This is in accordance with SRIM simulations. XRD and electron diffraction analyses suggest a structural evolution in relation to L. After irradiation, Zr (0002) and Nb (110) reflexions overlap for L=6 nm. For the periodicity L > 6 nm the Zr (0002) peak is shifted to higher angles and Nb (110) peak is shifted to lower angles.
Keywords:
Zr/Nb multilayers; ion irradiation; strain; XRD; SIMS
Available at various institutes of the ASCR
Effect of implantation of C, Si and Cu into ZrNb nanometric multilayers
Sputter-deposited Zr/Nb nanometric multilayer films with a periodicity (L) in the range from 6 to 167 nm were subjected to carbon, silicon and copper ion irradiation with low and high fluences at room ...
Production and characterization of micro-size pores for ion track etching applications
Cannavó, Antonino; Havránek, Vladimír; Lavrentev, Vasyl; Torrisi, L.; Cutroneo, Mariapompea; Ceccio, Giovanni; Torrisi, Alfio; Horák, Pavel; Vacík, Jiří
2019 - English
For many years the applications of ion track etch materials have increased considerably, like charged particles detection, molecular identification with nanopores, ion track filters, magnetic studies with nanowires and so on. Over the materials generally used as track detector, the Poly-Allyl-Diglycol Carbonate (PADC), offers many advantages, like its nearly 100 % detection efficiency for charged particle, a high resistance to harsh environment, the lowest detection threshold, a high abrasion resistance and a low production costs. All of these properties have made it particularly attractive material, even if due to its brittleness, obtaining a thin film (less than 500 μm) is still a challenge. In this work, PADC foils have been exposed to a-particles emitted by a thin radioactive source of 241Am and to C ions from the Tandetron 4130 MC accelerator. The latent tracks generated in the polymer have been developed using a standard etching procedure in 6.25 NaOH solution. The dependence of the ion tracks' geometry on the ion beam energy and fluence has been evaluated combining the information obtained through a semiautomatic computer script that selects the etched ion tracks according to their diameter and mean grey value and nanometric resolution images by atomic force microscopy.
Keywords:
AFM; image analysis; PADC polymer
Available at various institutes of the ASCR
Production and characterization of micro-size pores for ion track etching applications
For many years the applications of ion track etch materials have increased considerably, like charged particles detection, molecular identification with nanopores, ion track filters, magnetic studies ...
Preparation of ppHMDSO Thin Films in Capacitively Coupled RF Glow Discharges under Dusty Plasma Conditions
Homola, V.; Buršíková, V.; Kelar, L.; Kelarová, Š.; Stupavska, M.; Peřina, Vratislav
2018 - English
The deposition of organosilicone thin films from mixture of hexamethyldisiloxane (HMDSO) and oxygen by using capacitively coupled R.F. glow discharges under dusty plasma conditions was investigated. High resolution topography and mechanical property maps of the prepared films were acquired by using atomic force microscopy techniques. The chemical bond and composition of the deposited films were analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The mechanical properties of the films were studied using quasistatic as well as dynamic nanoindentation tests and their surface free energies were evaluated by means of contact angle measuring technique using several testing liquids exhibiting various surface tensions. The thermal stability of the films was studied using thermal desorption spectroscopy. Neural network modelling was used to study the effect of plasma parameters on the hardness of ppHMDSO films
Keywords:
Hexamethyldisiloxane; mechanical properties; oxygen; PECVD
Available at various institutes of the ASCR
Preparation of ppHMDSO Thin Films in Capacitively Coupled RF Glow Discharges under Dusty Plasma Conditions
The deposition of organosilicone thin films from mixture of hexamethyldisiloxane (HMDSO) and oxygen by using capacitively coupled R.F. glow discharges under dusty plasma conditions was investigated. ...
Role of activation analysis in the preparation of reference materials
Kučera, Jan
2018 - English
The fundamentals of neutron activation analysis (NAA) and prompt gamma activation analysis (PGAA) and practices of both methods are briefly review, together with enlightening their specific role in the preparation of reference materials. The importance of homogeneity testing for the certification and use of reference materials (RMs) using NAA is appraised. Examples of the use of NAA and PGAA for the certification of element contents in environmental, biological, and material science RMs produced by world-leading institutions, such as U.S. NIST, IRMM, IAEA and by national institutions, as well, at the Nuclear Physics Institute within last almost 30 years are presented.
Keywords:
analytical methods; INAA; RNAA
Available at various institutes of the ASCR
Role of activation analysis in the preparation of reference materials
The fundamentals of neutron activation analysis (NAA) and prompt gamma activation analysis (PGAA) and practices of both methods are briefly review, together with enlightening their specific role in ...
Stability of the sodium content in selected botanical reference materials
Kameník, Jan; Kučera, Jan; Borovička, Jan; Havránek, Vladimír
2018 - English
Sodium mass fractions in NIST standard reference materials (SRM) SRM 1547 Peach Leaves and SRM 1515 Apple leaves determined by INAA in our laboratory in recent years has been higher than the certified values. Similarly, increased values were published for SRM 1547 by several other laboratories. The increased Na mass fractions was found also for freshly opened SRM 1547 bottle and for material originating from a different lab. Increased Na mass fractions were confirmed by ICP-MS analysis of both materials. Analysis of archived samples revealed that sodium mass fraction in materials stored in polyethylene capsules is in agreement with the certified values. The sodium content in the glass of SRM 1547 bottle was roughly 10 %. Direct measurement of the Na depth profile by micro-PIXE was not indicative whether Na is released, i.g., by a glass corrosion due to residual humidity in the botanical material. However, a model experiment with freshly prepared and pulverized peach leaves demonstrated that such a scenario is possible for leaf-based materials. Although the study was focused on two NIST materials, the process is possible for any material with rather low Na content.
Keywords:
standard reference materials; analysis; methods
Available at various institutes of the ASCR
Stability of the sodium content in selected botanical reference materials
Sodium mass fractions in NIST standard reference materials (SRM) SRM 1547 Peach Leaves and SRM 1515 Apple leaves determined by INAA in our laboratory in recent years has been higher than the certified ...
Stanovení prvkového složení drog neutronovou aktivační analýzou pro zjišťování jejich původu - studie proveditelnosti
Kučera, Jan; Kameník, Jan; Sabol, J.; Šesták, B.; Kolář, P.; Roman, M.
2018 - Czech
Analyzovali jsme pět vzorků heroinu a pět vzorků kokainu zachycených na území České republiky metodou instrumentální neutronové aktivační analýzy (INAA). Alespoň v jednom z analyzovaných vzorků heroinu jsme stanovili 16 stopových prvků, ve vzorcích kokainu se jednalo o 9 stopových prvků. Pozoruhodné rozdíly až v rozmezí několika řádů, jsme zjistili v obsazích prvků Na, Cl, Cr, Zn a Br, zejména ve vzorcích heroinu. Přesnost výsledků INAA jsme prokázali simultánní analýzou certifikovaného referenčního materiálu NIST SRM 1547 Peach Leaves. Výsledky stanovení stopových prvků v heroinu jsme porovnali s výsledky zahraničních autorů. Dosažené výsledky ukazují na vysoký potenciál metody INAA pro prvkovou charakterizaci drog za účelem zjištění jejich původu, způsobu výroby a čištění či způsobu ředění pro konečné uživatele. Pokládáme za účelné pokračovat v analýzách většího množství vzorků s konečným cílem vytvoření databáze prvkového složení vzorků zkonfiskovaných na území ČR, která by později mohla být rozšířena ve spolupráci se zahraničními protidrogovými a policejními orgány v mezinárodním měřítku. We analyzed five samples of heroine and five samples of cocaine seized in the Czech Repulic using instrumental neutron activation analysis (INAA). In the heroine speciments, we determined 16 trace elements in at least one of the samples analyzed, in the cocaine speciment, 9 trace elements could be determined. We have found remarkable differences, up to several orders of magnitude, in contents of the elements Na, Cl, Zna and Br, especially in the heroine samples. The accuracy of INAA results was proved by simultaneous analysis of a certified reference material NIST SRM 1547 Peach Leaves. The results of trace element determination in heroine samples are compard with those published by autors from abroad. The results obtained show a high potential of INAA for the drug elemental characteriaztion aimed at determination of their provenance, procedures used for their manufacturing and purification and cutting for the end users. The results achieved also suggest that it is desirable to analyze more samples with the final aim of establishing a database of elemental composition of drugs seized in the Czech Republic, which could possibly be extended later, in cooperation with foreign drug abuse and police bodies, at the international level.
Keywords:
heroine; cocain; INAA
Available on request at various institutes of the ASCR
Stanovení prvkového složení drog neutronovou aktivační analýzou pro zjišťování jejich původu - studie proveditelnosti
Analyzovali jsme pět vzorků heroinu a pět vzorků kokainu zachycených na území České republiky metodou instrumentální neutronové aktivační analýzy (INAA). Alespoň v jednom z analyzovaných vzorků ...
Ultra-low intensity proton beams for radiation response related experiments at the U-120M cyclotron
Matlocha, Tomáš; Křížek, Filip
2018 - English
The U-120M cyclotron at the Nuclear Physics Institute (NPI) of the Czech Academy of Sciences in Rez is used for radiation hardness tests of electronics for high-energy physics experiments. These tests are usually carried out with proton fluxes of the order of 105–109 proton cm-2 s -1. Some tests done for the upgrade of the Inner Tracking System of the ALICE experiment at CERN, however, required proton beam intensities several orders of magnitude lower. This paper presents a method which has been developed to achieve the proton beam flux of the order of 1 proton cm-2 s -1. The method is mainly based on reduction of the discharge current in the cyclotron internal Penning type ion source. Influence of this new operation mode on the lifetime of ion source cathodes is discussed.
Keywords:
ultra-low intensity proton flux; penning ion source; negative hydrogen yield resonance; cyclotron irraditation facility; radiation hardness tests
Available at various institutes of the ASCR
Ultra-low intensity proton beams for radiation response related experiments at the U-120M cyclotron
The U-120M cyclotron at the Nuclear Physics Institute (NPI) of the Czech Academy of Sciences in Rez is used for radiation hardness tests of electronics for high-energy physics experiments. These tests ...
Measurements and usage of cross sections of various (n,chi n) threshold reactions
Chudoba, Petr; Vrzalová, Jitka; Svoboda, Ondřej; Krása, Antonín; Kugler, Andrej; Majerle, Mitja; Suchopár, Martin; Wagner, Vladimír
2017 - English
Current trend in nuclear reactor physics is a transition from technologies using thermal neutrons to technologies utilizing fast neutrons. Unfortunately focus was put mainly on the thermal neutrons for a long time and lead to very good knowledge about this low energy region, but very scarce coverage of the high energy region. This means that there is a gap in the knowledge of excitation functions for higher energies. This gap spreads from 20 MeV up to 1 GeV and higher. This is exactly the energy region needed for description of advanced nuclear systems such as accelerator driven systems (ADS). Our group from Nuclear Physics Institute (NPI) of the CAS is a member of an international collaboration Energy & Transmutation of Radioactive Waste (E&T RAW). This collaboration focuses on ADS for many years. In order to measure neutron field within ADS models it is necessary to know excitation functions of reactions used to monitor the neutron field. In many cases there are almost no experimental data for suitable reactions. Worse and quite common case is that there are no data at all. Therefore we are also focusing on measurements of these data in order to fill the databases as well as to allow further improvements of codes for nuclear data calculations.
Keywords:
cross section; NPI; E&T RAW
Available at various institutes of the ASCR
Measurements and usage of cross sections of various (n,chi n) threshold reactions
Current trend in nuclear reactor physics is a transition from technologies using thermal neutrons to technologies utilizing fast neutrons. Unfortunately focus was put mainly on the thermal neutrons ...
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