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    Wyświetlanie 1-4 z 4
    Tytuł:
    Precipitation Processes during Non-Isothermal Ageing of Fine-Grained 2024 Alloy
    Autorzy:
    Kozieł, J.
    Błaż, L.
    Włoch, G.
    Sobota, J.
    Lobry, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/352499.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    AA2024 alloy
    scrap metal milling
    structure refining
    powder metallurgy
    precipitation hardening
    Opis:
    Mechanical alloying and powder metallurgy procedures were used to manufacture very fine-grained bulk material made from chips of the 2024 aluminum alloy. Studies of solution treatment and precipitation hardening of as-received material were based on differential scanning calorimetry (DSC) tests and TEM/STEM/EDX structural observations. Structural observations complemented by literature data lead to the conclusion that in the case of highly refined structure of commercial 2024 alloys prepared by severe plastic deformation, typical multi-step G-P-B →θ” →θ’ →θ precipitation mechanism accompanied with G-P-B →S” →S’ →S precipitation sequences result in skipping the formation of metastable phases and direct growth of the stable phases. Exothermic effects on DSC characteristics, which are reported for precipitation sequences in commercial materials, were found to be reduced with increased milling time. Moreover, prolonged milling of 2024 chips was found to shift the exothermic peak to lower temperature with respect to the material produced by means of common metallurgy methods. This effect was concluded to result from preferred heterogeneous nucleation of particles at subboundaries and grain boundaries, enhanced by the boundary diffusion in highly refined structures. Transmission electron microscopy and diffraction pattern analysis revealed the development of very fine Al4C3 particles that grow due to the chemical reaction between the Al matrix and graphite flakes introduced as a process control agent during the preliminary milling of chips. Al4C3 nano-particles are formed at high temperatures, i.e. during hot extrusion and the subsequent solution treatment of the samples. Highly refined insoluble particles such as aluminum carbide particles and aluminum oxides were found to retard recrystallization and reduce recovery processes during solution treatment of preliminarily milled materials. Therefore, the as-extruded material composed of a milled part and chip residuals retained its initial bimodal structure in spite of solution heat treatment procedures. This points to a high structural stability of the investigated materials, which is commonly required for new technologies of high-strength Al-based materials production.
    Źródło:
    Archives of Metallurgy and Materials; 2016, 61, 1; 169-176
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Improving environmental odor measurements : comparison of lab-based standard method and portable odor measurement technology
    Autorzy:
    Maurer, D. L.
    Bragdon, A. M.
    Short, B. C.
    Ahn, H.
    Koziel, J. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/204983.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    odor
    volatile organic compounds
    air quality measurements
    standardization
    olfactometry
    Opis:
    Current standard odor measurement methods are lab-based and require substantial investment in hardware, sample collection, training, and maintenance. Odor samples must be collected in the field using bags and brought to the lab to test. This can be a time-consuming process, with the possibility of the sample loss. The actual odor measurements are based on dilution olfactometry, embodied in the AC’SCENT® International Olfactometer, following the ASTM E679-04 standard. In recent years a portable olfactometer, the Scentroid SM100i, has been developed for odor measurements. The portable olfactometer has many advantages over lab-based standard method, especially the lower cost-per-sample. However, very little is known about the performance and reliability of portable olfactometer where the dilutions are controlled with orifices in metallic plates. It is important to evaluate the Scentroid SM100i accuracy to determine the usefulness of using it as a comparable technology for odor measurements. The main objective of this research is to compare the performance of the lab-based ASTM E679-04 method with portable odor measurement technology. Specific objectives include: (1) determining the accuracy of the dilution ratios specified by the manufacturer of both the AC’SCENT International Olfactometer and the Scentroid SM100i; (2) comparing results between olfactometers using n-butanol, a commonly used standard gas in the olfactometry field, and (3) determining the accuracy of odor measurement using real odor samples collected from livestock farms in Iowa. The AC’SCENT olfactometer had an average percent error between the factory specifications and measured dilution ratios of 5.23% compared with 14.1% for Scentroid SM100i (using plate i-2 with dilution range most comparable to the AC’SCENT olfactometer). The use of other dilution plates resulted in average percent errors ranging from 9.68% to 25.31%. The Scentroid SM100i deviated from the manufacturer specifications for flowrates and dilution ratios, but these flowrates were generally consistent with each dilution setting. Overall, the Scentroid SM100i overestimated the odor concentrations with the mean difference of 22.9% (ranging from 0.95% to 93.34%). When the post-measurement adjustment using dilution correction was made, the mean percent average difference was 11.8%.
    Źródło:
    Archives of Environmental Protection; 2018, 44, 2; 100-107
    2083-4772
    2083-4810
    Pojawia się w:
    Archives of Environmental Protection
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Structure of the amorphous-crystalline Fe66Cu6B19Si5Nb4 alloy obtained by the melt-spinning process
    Struktura amorficzno-krystalicznego stopu Fe66Cu6B19Si5Nb4 otrzymanego metodą melt-spinning
    Autorzy:
    Kozieł, T.
    Latuch, J.
    Zielińska-Lipiec, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/355938.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    metallic glasses
    amorphous/crystalline composites
    melt-spinning
    szkło metaliczne
    kompozyty amorficzno-krystaliczne
    metoda melt-spinning
    Opis:
    This paper presents structure investigations of the rapidly cooled Fe66Cu6B19Si5Nb4 alloy. A proper selection of chemical composition enabled in-situ formation of the amorphous-crystalline composite during the melt spinning process. Liquid phase separation into the Fe-rich and the Cu-rich phases was confirmed. The microstructures of alloy, melt-spun from 1723 and 1773 K, are composed of the Fe-rich amorphous matrix and Cu-rich spherical crystalline precipitates. For the higher melt-ejection temperature, no coarse precipitates could be observed. Amorphous nature of the Fe-rich matrix was confirmed by presence of a broad diffraction maximum on the X-ray diffraction patterns, a halo ring on the electron diffraction pattern as well as presence of exothermic effects, related to the crystallization of the Fe-rich amorphous matrix, in the differential scanning calorymetry. Beside presence of copper, revealing positive heat of mixing with iron, relatively large supercooled liquid region, was noticed.
    Praca przedstawia badania kompozytu amorficzno-krystalicznego otrzymanego w stopie Fe66Cu6B19Si5Nb4. Badania obejmowały rentgenowską analizę fazową (XRD), skaningową kalorymetrie różnicową (DSC), mikroskopię swietlną (LM), skaningową mikroskopię elektronową (SEM) i transmisyjną mikroskopię elektronową (TEM). Odpowiedni dobór składu chemicznego umożliwił uzyskanie kompozytu amorficzno-krystalicznego dzięki wykorzystaniu zjawiska podziału w stanie ciekłym w efekcie dodatniego ciepła tworzenia roztworu pomiędzy żelazem i miedzią. Mikrostruktury badanego stopu, po odlaniu z temperatury 1723 i 1773 K, składają się z amorficznej osnowy bogatej w żelazo i krystalicznych kulistych wydzieleń bogatych w miedź. Dla wyższej temperatury odlewania nie obserwowano dużych wydzieleń. Obecność fazy amorficznej została potwierdzona poprzez obecność halo na dyfrakcji elektronowej oraz efekt cieplny egzotermiczny w badaniach skaningowej kalorymetrii różnicowej, związany z krystalizacją osnowy bogatej w żelazo. Pomimo dodatku miedzi, wykazującej dodatnie ciepło tworzenia roztworu z żelazem, wyznaczony zakres cieczy przechłodzonej jest względnie duży.
    Źródło:
    Archives of Metallurgy and Materials; 2013, 58, 2; 601-605
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Zr Purity and Oxygen Content on the Structure and Mechanical Properties of Melt-Spun and Suction-Cast Cu46Zr42Al7Y5 Alloy
    Autorzy:
    Kozieł, T.
    Latuch, J.
    Cios, G.
    Bała, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/352353.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    metallic glasses
    bulk metallic glasses
    melt spinning
    suction casting
    Opis:
    The effect of oxygen content in zirconium on the structure and mechanical properties of the Cu46Zr42Al7Y5 alloy, in the form of melt-spun ribbons and suction-cast rods, was investigated. Two types of Zr, rod and crystal bar of different nominal purities and oxygen contents, were used to synthesize the alloy by arc melting. Rapidly solidified ribbons were produced by melt spinning and their amorphous structures were confirmed by X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). Bulk samples in the form of rods were cast using a special water-cooled suction casting unit attached to the arc melting system. XRD and DSC studies proved the amorphous structure of the bulk alloy synthesized from low-oxygen Zr and partial crystallization of the same alloy for high-oxygen Zr. In both bulk samples, uniformly distributed crystalline particles were identified as yttrium oxides. Higher mean compressive strength of amorphous alloy was observed. The hardness of amorphous phase was close to 500 HV1 in both bulk alloys, while the hardness of crystalline dendritic areas, observed in the alloy synthesized from high oxygen Zr, was lower by about 50 HV1.
    Źródło:
    Archives of Metallurgy and Materials; 2016, 61, 2B; 1215-1219
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-4 z 4

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