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    Wyświetlanie 1-4 z 4
    Tytuł:
    Growth Law for Columnar Structure within the Copper and Copper Alloys Solidifying at a High Peclet Number
    Autorzy:
    Kwapisiński, Piotr
    Wołczyński, Waldemar
    Powiązania:
    https://bibliotekanauki.pl/articles/27765081.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    continuously cast copper ingots
    perturbation wavelength
    criterion of marginal stability
    Opis:
    The copper and copper alloys’ ingots have been subjected to structural observation in order to estimate the Peclet Number at which these ingots were solidifying. It was stated that the formation of columnar structure within the ingots occurred at a high Peclet Number, higher than the threshold value of this parameter, Pe = 500. The formulated relationships of the Growth Law correspond to a high Peclet Number due to application of the adequate development in series of the Ivantsov’s function. The Growth Law has been developed on the basis of the definition of the wavelength of perturbation which leads to the dispersion of the planar s/l interface. New definition of the index of stability connected with the behavior of solute concentration at the s/l interface has been delivered. The current definition is related to non-equilibrium solidification. The index can be easily calculated using some parameters delivered by a given Cu-X phase diagram. Physical meaning of the formulated Growth Law has also been presented.
    Źródło:
    Archives of Metallurgy and Materials; 2023, 68, 2; 579--584
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pattern Selection in the Eutectic Growth - Thermodynamic Interpretation
    Autorzy:
    Wołczyński, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/352184.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    criterion of lower minimum entropy production
    structural competition
    marginal stability
    irregular growth
    microsegregation
    Opis:
    The (Zn) – single crystal strengthened by the E = (Zn) + Zn16 Ti eutectic precipitate is subjected to directional growth by the Bridgman’s system and current analysis. Experimentally, the strengthening layers (stripes) are generated periodically in the (Zn) – single crystal as a result of the cyclical course of precipitation which accompanies the directional solidification. These layers evince diversified eutectic morphologies like irregular rods, regular lamellae, and regular rods. The L – shape rods of the Zn16 Ti – intermetallic compound appear within the first range of the growth rates when the irregular eutectic structure is formed. Next, the branched rods transform into regular rods and subsequently the regular rods into regular lamellae transitions can be recorded. The regular lamellae exist only within a certain range of growth rates. Finally, the regular rods reappear at some elevated growth rates. A new solution to the diffusion equation is provided to describe the micro-field of the solute concentration in the liquid adjacent to the front of the growing eutectic structure. The solution is based on the mass balance in the considered system. Moreover, the existence of the protrusion of the leading eutectic phase over the wetting one is required by the mass balance. The appearance of the d – protrusion in the growing eutectic is well confirmed by the experimental observations of the frozen solid/liquid interface.The mentioned solution satisfies the concept of the eutectic coupled growth according to which undercooling of the leading phase is less than undercooling of the wetting eutectic phase. Also, the Ti – solute micro-segregation / redistribution is analyzed within the matrix of the single crystal. The micro-segregation is described as a result of the solution to the adequate, newly developed differential equation. The definition for the solute redistribution is given by the subsequently / separately formulated relationship. This definition takes into account both extent -, and intensity of the solute redistribution. Finally, the entropy production is calculated for the regular lamellae -, and for the regular rods formation, respectively. The entropy production is a function of some parameters which define the eutectic phase diagram, coefficient of the diffusion in the liquid, and some capillary parameters connected with the mechanical equilibrium located at the triple point of the solid/liquid interface. Branches formation is related to the marginal stability. A new criterion is formulated and subjected to successful verification. It is: in the structural – thermodynamic competition the winner is this kind of the pattern for which minimum entropy production has a lower value.
    Źródło:
    Archives of Metallurgy and Materials; 2020, 65, 2; 653-666
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nature of Segregation in the Steel Static and Brass Continuously Cast Ingots
    Autorzy:
    Wołczyński, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/356511.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    macro-segregation maps
    brass ingots morphology
    marginal stability criterion
    Growth Law for columnar structure
    formation
    Opis:
    Experimental observations of the steel morphology as well as measurements of the solutes concentration in the macro-scale were made on the basis of the vertical cut at the mid-depth of the 15-tons steel forging ingot serially produced in one of the steel plant in Poland. Experimental observations of the morphology accompanied by the measurements of the Peclet Number were also made on the cross-section of the continuously cast brass ingots serially produced in the copper / brass industry in Poland. The performed measurements allowed to work out some maps of the alloying elements segregation for the longitudinal section of the steel static ingot and a Growth Law for the columnar grains formation in the brass ingots. The marginal stability criterion has been applied to the last mentioned development / description. Some suggestions for the micro-segregation measurement mode in the columnar structure are derived.
    Źródło:
    Archives of Metallurgy and Materials; 2018, 63, 4; 1915-1922
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermodynamic pattern selection in the stripes generated periodically during the (Zn) - single crystal growth
    Termodynamiczna selekcja morfologii prążków generowanych periodycznie podczas wzrostu monokryształu (ZN)
    Autorzy:
    Wołczyński, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/353058.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    minimum entropy production
    marginal stability
    surface tension anisotropy
    structure selection
    structure transformation
    minimum produkcji entropii
    marginalna stabilność
    napięcie powierzchniowe
    wybór struktury
    przekształcenie struktury
    Opis:
    The (Zn) - hexagonal single crystal growth was performed by the Bridgman system. Some eutectic stripes were generated periodically in the single crystal. The stripes consisted of the strengthening inter-metallic compound, Zn16Ti and (Zn) - solid solution. Two morphology transitions were recorded. At the first threshold growth rate, L-shape irregular rods transformed into regular lamellar structure. The transition was accompanied by the irregular into regular morphology alteration. The regular lamella into regular rods transition occurred at the second threshold growth rate. The new, proposed thermodynamic pattern selection criterion (PSC) of the lower minimum entropy production was applied to describe the structural transitions. The solid/liquid interface perturbation of the (Zn) - phase was referred to the marginal stability.
    Heksagonalny monokryształ roztworu stałego (Zn) został wyprodukowany w układzie Bridgmana. Prążki eutektyczne zostały wygenerowane periodycznie w monokrysztale. Prążki składały się z umacniającego związku międzymetalicznego Zn16Ti oraz roztworu stałego (Zn). Zarejestrowano dwa przejścia morfologiczne. Przy pierwszej prędkości progowej nieregularne włókna o przekroju L doznały transformacji w regularne płytki. Temu przejściu towarzyszyła przemiana morfologii nieregularnej w regularna. Regularne płytki dokonały transformacji w regularne włókna przy drugiej prędkości progowej. Niższe minimum produkcji entropii to proponowane, nowe kryterium termodynamiczne dla selekcji struktur, jakie zastosowano by opisać przejścia strukturalne. Perturbacja frontu krystalizacji fazy (Zn) została odniesiona do stanu stabilności marginalnej.
    Źródło:
    Archives of Metallurgy and Materials; 2013, 58, 2; 309-313
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-4 z 4

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