Structure and Shape of Iron Dendrites in the Cu–Fe Alloy with the Addition of Carbon, Which Was Poured, Cooled and Solidified Under the Action of a Magnetostatic Field
O. V. Nogovitsyn$^{1}$, V. O. Seredenko$^{1}$, Yu. M. Romanenko$^{2}$, O. V. Seredenko$^{1}$, O. V. Chystyakov$^{1}$
$^{1}$Физико-технологический институт металлов и сплавов, НАН Украины, бульв. Академика Вернадского, 34/1, 03142 Киев, Украина
$^{2}$Национальный технический университет Украины «Киевский политехнический институт имени Игоря Сикорского», просп. Берестейский, 37, 03056 Киев, Украина
Получена: 03.05.2024; окончательный вариант - 09.07.2024. Скачать: PDF
Cu–Fe alloys with both a copper base and dispersed (≅ 10 μm) globular inclusions of the iron phase are promising as materials with high special properties. Foundry technologies are low-cost and low-limited by the thickness of the products; however, at their low cooling rates (up to 50 K/s), branched dendrites (≅ 100 μm) are formed. Therefore, it is important to improve the dispersion of the iron phase and its structure. As established, in the Cu–20% Fe alloy smelted in an induction crucible furnace (at temperature of 1723 K), microalloyed with 0.05% C, poured into cylindrical forms (Re = (1.7–4.0)⋅104, Ri = 6.0⋅10−5, specific energy and power of mixing are of 4.4 J/kg and 1.1 W/kg, respectively), structural zones are formed: peripheral zone cooled at 19.6 K/s with a length of 17% of the casting radius with suspension structure (inclusions of 7.5 μm) and central one (at 1.1 K/s) with dendrites up to 350 μm, of which 40% are divided into fragments. A constant magnetic field applied to the melt poured in and solidified forms a magnetohydrodynamic boundary layer (Hartmann) of the melt (Ha = 13.2) with a thickness of 260 μm, which is accompanying the crystallization front during the formation of the peripheral zone, increasing the heat transfer (k = 72.9). The Hartman layer and field-enhanced microcurrents near the interphase surface of inclusions caused by the Marangoni and Seebeck effects during recalescence of dendrites increase the cooling rate of the periphery (30.1 K/s), its width (34% of the radius of the casting), and the dispersion of the suspension (3.3 μm), grinding the dendrites of the central zone (150 μm) and dividing them into fragments up to 90%. Increased mixing of the melt in the middle of the sub-melted dendrites destroys the continuous shells on the interphase surface of inclusions and the columnar structure and increases the dispersion (size ≅ 1 μm) of their subgrains. The results of the perspective work on the fabrication of copper alloys with dispersed globularized dendritic inclusions spread over the entire volume of cylindrical castings with a cavity, flat bimetallic and continuously cast cylindrical and flat bodies.
Ключевые слова: Cu–Fe alloy, melt cooling, microalloying with carbon, permanent magnetic field, iron dendrites, cast structure.
URL: https://mfint.imp.kiev.ua/ru/abstract/v46/i12/1185.html
PACS: 61.25.Mv, 61.72.Mm, 68.70.+w, 81.05.Bx, 81.30.Fb, 83.60.Np, 83.80.Gh