Calorific Value of Coke 5. Quenching Method

Мирошниченко, И. В.; Мірошниченко, Д. В.; Shulga, I. V.; Balaeva, Ya. S.

doi:10.3103/s1068364x20040080

Cited by 6 publications

(9 citation statements)

References 8 publications

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“…As mentioned before specific features of rapid solidification are the localisation of the diffusion fields and the transition to solute trapping (k v → 1) that occurs at a finite velocity of the solid-liquid interface. It was detected experimentally first by Olsen and Hultgren [287] in 1950, and Duwez et al [288] in 1960 and early investigated by Miroshnitchenko [289,290]. To describe such phenomena, first theories of rapid solidification were developed [291][292][293][294][295].…”

Section: Rapid Solidificationmentioning

confidence: 99%

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Progress in modelling solidification microstructures in metals and alloys: dendrites and cells from 1700 to 2000

Kurz

Fisher

Trivedi

2018

International Materials Reviews

154

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This is the first account of the history of our understanding of, and ability to model, solidification microstructures. Its objective is to retrace the scientific steps made, from the earliest observations of the eighteenth century to our present-day understanding of dendrites and eutectics. Because of the abundance of information, especially that added during the present century, sub-division was essential: this being the first of three articles. They cover dendrites and cells from 1700 to 2000, and then from 2001 to 2015 and finally eutectics and peritectics from 1700 to 2015. The authors have striven always to identify the genesis of every advance made, being aware that such a compact history must leave many worthy contributions by the wayside; others will doubtless complete the history. This review shows how crossfertilisation between theory and experiment, and basic and applied research led to both the posing and answering of challenging fundamental questions, thus rewarding society with beneficial results.

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Section: Rapid Solidificationmentioning

confidence: 99%

“…It was detected experimentally first by Olsen and Hultgren [287] in 1950, and Duwez et al. [288] in 1960 and early investigated by Miroshnitchenko [289,290]. To describe such phenomena, first theories of rapid solidification were developed [291–295].…”

Section: Rapid Solidificationmentioning

confidence: 99%

Progress in modelling solidification microstructures in metals and alloys: dendrites and cells from 1700 to 2000

Kurz

Fisher

Trivedi

2018

International Materials Reviews

154

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“…Upon cooling, after the melt reaches the temperature of crystallization beginning, the Ti-B alloy containing less than 48 at.% B (assuming an uniform distribution of components), corresponds to a liquid solution of titanium and boron with the TiB phase crystallizing in the melt. As is known [6], to start the melt crystallization, its overcooling ΔT from the phase equilibrium temperature is necessary. At that, the new phase nuclei originate by fluctuation way and grow or dissolve depending on the ratio of their effective nucleus radius to the critical radius r cr of the nucleus.…”

Section: Resultsmentioning

confidence: 99%

Features of the welded seam material crystalliza-tion in Ti-TiB alloy under electron-beam welding conditions

Loboda,

Zvorykin,

Zvorykin

et al. 2023

Mech. Adv. Technol.

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Natural metal composite materials represent a promising class of modern structural materials that need to be welded. Such materials can be welded by fusion, as has been established with the Ti-TiB alloy as an example. The enhanced operational properties of such materials are determined by the microstructure, which is characterized by the presence of microfibers of borides, carbides, or silicides in the metal matrix. To preserve the mechanical properties of materials in a welded joint, it is necessary to ensure the formation of reinforcing microfibers in the welded seam material. Determination of formation mechanism of boride microfibers, originated in the welded seam material, will become the basis for optimizing of fusion welding modes, in particular, electron beam welding mode. The purpose of this study is the determination of formation mechanism of boride microfibers originated in the welded seam material. Two most probable variants of the formation mechanism are analyzed, which involve eutectic decomposition during crystallization from a liquid melt or eutectoid decomposition from a metastable crystallized alloy. The third version is a mixed variant of the two above-mentioned mechanisms. In the article the results of metallographic analysis of features of boride phase distribution and an analysis of elemental composition of boride fibers based on local Auger electron spectroscopy are presented. The object of study was a Ti-TiB alloy joint obtained by electron-beam welding. The analysis factors were the features of size, orientation, and nature of the distribution of boride phase microfibers in different areas of the welded seam. The characteristic elemental composition of boride microfibers, which characterizes the correspondence to equilibrium phases, is also studied. The degree of deviation of the ratio of boron and titanium in such a phase from the thermodynamically equilibrium in different layers of the material of the welded seam, formed by an electron beam in vacuum, is determined. The dependence of boride phase distribution under various conditions of heat exchange in the welded seam material on the side surfaces and in the central regions is established. It is shown that some of boride microfibers formed in the material of the welded seam are characterized by a deviation from the thermodynamically stable composition ТіВn (n = 1) to ТіВn (n = 0.85). The dendritic nature of boride microfibers distribution and the presence of meta-stable phase formations on Ti and B basis provide the grounds for proposing the predominant mechanism for the formation of structure of the welded seam material in the Ti-TiB alloy during crystallization. An analysis of hypothetical variants of the formation mechanism of boride microfibers originated in the welded seam material showed that the formation of a dendritic type of structure is characteristic for the growth of crystals of a new phase in the liquid phase. Such growth is characterized by the formation of equilibrium phases. The presence of a significant amount of non-equilibrium boride phase in the welded seam indicates the residue of non-equilibrium boron in the titanium matrix and continuation of growing of boride fibers in the crystallized welded seam. A determined mechanism for formation of boride microfibers originated in the welded seam material is eutectic decomposition during crystallization from a liquid melt with the formation of TiB microfibers and further growth of such crystals due to eutectoid decomposition from a metastable crystallized Ti-TiB alloy. The results obtained make it possible to understand the mechanism of formation of a welded seam in welded natural-composite metal materials, which permits to develop the recommendations for optimizing the welding technology for such materials.

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“…However, if the solidification is very rapid, one or other of the metal's high-temperature modifications may be quenched and then remain in a metastable state at room temperature for a while, converting to a stable phase with time. 93,94 Accordingly, another argument for the phenomenon in point will be electrochemical phase formation in polymorphous metals leading to metastable polymorphs typical of metal crystallization from a liquid state at extremely high rates. 61,64,95 Identification of metastable modifications.-To implement the above idea, a study was carried out into the structure of samples of the polymorphous metal manganese obtained by electrodeposition in ammonium chloride solution at current densities ranging from 5.0 to 25.0 A dm −2 and temperature 22 °C corresponding to an undercooling of ΔТ = 1224 K. Also studied were electrodeposits of the polymorphous metal cobalt obtained in a sulphate solution at temperature 23 °C and current densities from 5.0 to 20.0 A dm −2 ; in this case, the metal's liquid phase must have been exposed to an undercooling of ΔТ = 1472 K. X-ray diffraction analysis was carried out using a modified DRON-3 X-ray diffractometer with Cu-K α irradiation.…”

Section: First Principal Hypothesismentioning

confidence: 99%

“…(1) the crystallization of the electrodepositing polymorphous metal in the form of metastable modification, which is identical to the one of the same cast metal solidified from liquid state in saturated hydrogen environment; 111 (2) the appearance in the electrodepositing metal of a porous structure that has all the features characteristic of the porous structure of a cast material solidified from a liquid state in a saturated hydrogen environment; 111 (3) an increase in metal porosity with an increase in its saturation with hydrogen during electrodeposition. 111 Electrochemical high-defect crystalline phase formation in metals.-Idea ten and its realization.-It is well-known 94,124 that liquid-quenched crystalline metals have extremely high vacancy concentrations that may run to 10 −4 . This is 15 orders of magnitude more than 10 −19 , the equilibrium vacancy concentration value measured following crystallization under normal conditions.…”

Section: First Principal Hypothesismentioning

confidence: 99%

Review—Electrochemical Phase Formation via a Supercooled Liquid State Stage: Metastable Structures and Intermediate Phases

Girin

2022

J. Electrochem. Soc.

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A review of experimental works proving the existence of the phenomenon of the electrochemical phase formation in metals and alloys via a supercooled liquid state stage is presented. The research findings focused on the electrochemical formation of metastable structures and intermediate phases, as well as on the structural features accompanying them. Electrochemical amorphous phase formation in metals and alloys, electrochemical quasicrystalline phase formation in metals, and electrochemical polymorphic phase formation in metals are discussed. Electrochemical hydrogen-related structure formation in metals, electrochemical high-defect crystalline phase formation in metals, and electrochemical texture-inhomogeneous structure formation in metals are considered. Electrochemical formation of intermediate phases in metals and alloys, electrochemical formation of eutectics in metallic alloys, and electrochemical formation of chemical compounds at the metallic cathode/electrodepositing metal interface are analyzed. Electrochemical reduction of ions in metals and alloys at a liquid cathode versus a solid chemically identical one, electrochemical phase formation of metals at chemically identical solid or liquid cathode, and electrochemical phase formation of alloys at chemically identical solid or liquid cathode are discussed.

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Calorific Value of Coke 5. Quenching Method

Cited by 6 publications

References 8 publications

Progress in modelling solidification microstructures in metals and alloys: dendrites and cells from 1700 to 2000

Progress in modelling solidification microstructures in metals and alloys: dendrites and cells from 1700 to 2000

Features of the welded seam material crystalliza-tion in Ti-TiB alloy under electron-beam welding conditions

Review—Electrochemical Phase Formation via a Supercooled Liquid State Stage: Metastable Structures and Intermediate Phases

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