Mechanisms of Layer Structure Formation in Peritectic Alloys

ABSTRACTThe mechanisms of layer structure formation in the two phase region of peritectic systems are discussed. Under diffusive growth conditions, a banded structure is predicted within a narrow composition range in the hypoperitectic composition. Experimental studies show the formation of an oscillatory structure in the hyperperitectic region. It is shown that this structure is induced by convection in the melt, and it is a novel structure in which a large single tree-like structure of primary phase is surrounded by the peritectic phase. Basic ideas of convection that lead to this tree-like morphology are described.

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Directional Solidification of Sn-Cu6Sn5 In Situ Composites

Advances in Materials Science and Engineering ◽

10.1155/2019/9210713 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Osvaldo Fornaro

Keyword(s):

Directional Solidification ◽

Eutectic Reaction ◽

Secondary Phase ◽

Phase Region ◽

Primary Phase ◽

Point Of View ◽

System Stability ◽

Two Phase ◽

Directional Growth ◽

Free Solder

The Sn-Cu system presents an important interest from academic and technological point of view because it is part of the family of alloys proposed as lead-free solder alloys for electronic components and also due to the mechanisms involved during the growth of the different phases. Sn-Cu system has two intermetallic phases, i.e., ε-Cu3Sn and η-Cu6Sn5, and η can be used as the negative (anode) electrode in Li-ion batteries, alone or as part of (Co,Ni)xCu6−xSn5-type composites. Obtaining this η phase from liquid with the appropriate chemical composition is a very difficult task because it has a formation temperature lower than liquidus for such a composition. In this way, the η phase appears as a consequence of a solid-solid transformation from the ε phase However, it is possible to find the η phase as the primary or secondary phase after a eutectic reaction for lower concentrations of Cu. On the other side, the Cu6Sn5 phase shows a hexagonal to monoclinic solid-solid transformation around 187°C, which could affect the mechanical system stability when it is used as solder. In this work, directional solidification at different growth velocities of hypereutectic Sn-Cu samples was performed. The resultant microstructure varies with the growth velocity, but it is formed for a fibber-like primary phase Cu6Sn5 which is projected towards the liquid phase. Behind this region, these fibbers are rounded by a two-phase Sn-Cu6Sn5 structure. In this way, three zones could to be defined in the sample during the directional growth: (i) an entirely solid two-phase region, formed by η rounded by β(Sn) + η eutectic-like structure, (ii) a two-phase solid (η) + liquid, and (iii) the remnant liquid in front of the interface.

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Rotors with a novel structure for enhanced follow-up dynamic mixing

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2020-0205 ◽

2021 ◽

Vol 19 (4) ◽

pp. 427-438

Author(s):

Xin Wen ◽

Yumei Ding ◽

Meinong Shi ◽

Hua Yan ◽

Xiahua Zuo ◽

...

Keyword(s):

Ph Value ◽

Experimental Studies ◽

Working Environment ◽

Mixing Efficiency ◽

Two Phase ◽

Mixing Angle ◽

Mixing Effect ◽

Novel Structure ◽

Working Performance

Abstract Nowadays, dynamic mixers are widely used in industry. But dynamic mixers have problems like low mixing efficiency and high mixing resistance. Therefore, many scholars are committed to improving the rotor inside the dynamic mixer to improve its working performance. In this paper, a new structure of spiral rotor with chamfer and perforation was designed for promoting the performance of the dynamic mixing equipment. We measured the pH value to find which rotor’s working performance is better. On this basis, a numerical simulation was conducted on the mixing angle of the two-phase fluid to explore the best working environment of the dynamic mixer. Experimental studies proved that the mixing effect of the new structure rotor was better. The simulation results showed that the mixing effect of the two-phase flow was better when it merged at 135°.

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Hot Rolling of FeSi Steels – Effects by Hot Rolling in the Two Phase Region

Materials Science Forum ◽

10.4028/www.scientific.net/msf.704-705.1161 ◽

2011 ◽

Vol 704-705 ◽

pp. 1161-1166 ◽

Cited By ~ 1

Author(s):

J. Schneider ◽

W. Jungnickel ◽

W. Müller ◽

Harti Hermann ◽

R. Kawalla

Keyword(s):

Phase Transformation ◽

Hot Rolling ◽

Experimental Studies ◽

Phase Region ◽

Process Conditions ◽

Stress Strain ◽

Two Phase ◽

Strain Behaviour ◽

Finish Rolling ◽

Effect Of Hot Rolling

Finish rolling in the two-phase region may offer new possibilities for improving the properties of the FeSi steels with phase transformation. Therefore a deeper understanding of the effects by hot rolling in the two phase region or mixed rolling: multistep hot rolling in the two phase region and in the ferrite region on the evolution of the microstructure is desirable. In this paper we will present the results of our experimental studies on the effect of hot rolling in the intercritical state on the hardening and softening in the ferrite state. It will be demonstrated that depending on the process conditions at hot rolling the austenite ferrite transformation affects the stress strain behaviour in the ferrite state at multistep hot rolling remarkable.

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A statistical theory of liquid crystalline mixtures: phase separation

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1976.0162 ◽

1976 ◽

Vol 352 (1668) ◽

pp. 41-56 ◽

Cited By ~ 38

Keyword(s):

Liquid Crystal ◽

Phase Separation ◽

Liquid Crystalline ◽

Experimental Studies ◽

Phase Region ◽

Crystal Formation ◽

Two Phase ◽

First Order ◽

Repulsive Forces

The molecular field theory of multicomponent liquid crystalline mixtures, developed by Humphries, James & Luckhurst, has been extended to investigate the possibility of phase separation in binary mixtures of rods and spheres. This extension indicates that the addition of a spherical solute to a liquid crystal depresses the transition from the isotropic to the nematic phase. The solute induced phase transition is first order, although the nematic and isotropic phases are found to be separated by a two-phase region consisting of both nematic and isotropic phases. These qualitative conclusions of the theory are in complete accord with experiment and there is also reasonable agreement with certain quantitative predictions. The same problem has been tackled using a lattice model with purely repulsive anisotropic interactions; this theory would appear to be marginally less successful than our own which is based on a weaker anisotropic potential. Consequently it is not possible to use experimental studies of phase separation in binary liquid crystal mixtures to demonstrate the rôle of repulsive forces in liquid crystal formation.

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The nature of the change of the surface temperature of the workpiece during hot rolling of pipe steel

MATEC Web of Conferences ◽

10.1051/matecconf/201822401104 ◽

2018 ◽

Vol 224 ◽

pp. 01104 ◽

Cited By ~ 1

Author(s):

Vladimir Nekit ◽

Sergey Platov ◽

Maksim Krasnov

Keyword(s):

Surface Temperature ◽

Hot Rolling ◽

Pipe Steel ◽

Practical Importance ◽

Experimental Studies ◽

Phase Region ◽

Work Piece ◽

Two Phase ◽

Deformation Processes ◽

Two Stages

The article is devoted the experimental studies of deformation and temperature parameters of rolling the pipe steel on the rolling mill 5000 PJSC “MMK”. Knowledge of the regularities of the change in the surface temperature of work piece during hot rolling under the conditions of thermo mechanical deformation processes is of great theoretical and practical importance. The temperature conditions determine the energy and force parameters of rolling, as well as the mechanical properties and microstructure of the finished products. The experimental rolling was carried out in two stages: roughing at 6 passes at a temperature of 1050-900 ° C and finishing at 18-20 passes at a temperature below the start of the phase transformation of 900 ° C. The finishing rolling has been carried out in a two-phase region at the stage of polymorphic transformation in the steel. Significant differences in the nature of temperature changes at different stages of rolling are revealed.

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Solution Properties and Phase Behavior of Ammonium Hexylene Octyl Succinate in Water and Water-Oil System

Dhaka University Journal of Pharmaceutical Sciences ◽

10.3329/dujps.v3i1.183 ◽

1970 ◽

Vol 3 (1) ◽

Author(s):

Md. Hamidul Kabir ◽

Ravshan Makhkamov ◽

Shaila Kabir

Keyword(s):

Critical Micelle Concentration ◽

Phase Behavior ◽

Liquid Crystalline ◽

Carbon Number ◽

Phase Region ◽

Solution Properties ◽

Middle Phase ◽

Two Phase ◽

Lamellar Liquid Crystal ◽

Drug Ingredient

The solution properties and phase behavior of ammonium hexylene octyl succinate (HOS) was investigated in water and water-oil system. The critical micelle concentration (CMC) of HOS is lower than that of anionic surfactants having same carbon number in the lipophilic part. The phase diagrams of a water/ HOS system and water/ HOS/ C10EO8/ dodecane system were also constructed. Above critical micelle concentration, the surfactant forms a normal micellar solution (Wm) at a low surfactant concentration whereas a lamellar liquid crystalline phase (La) dominates over a wide region through the formation of a two-phase region (La+W) in the binary system. The lamellar phase is arranged in the form of a biocompatible vesicle which is very significant for the drug delivery system. The surfactant tends to be hydrophilic when it is mixed with C10EO8 and a middle-phase microemulsion (D) is appeared in the water-surfactant-dodecane system where both the water and oil soluble drug ingredient can be incorporated in the form of a dispersion. Hence, mixing can tune the hydrophile-lipophile properties of the surfactant. Key words: Ammonium hexylene octyl succinate, mixed surfactant, lamellar liquid crystal, middle-phase microemulsion. Dhaka Univ. J. Pharm. Sci. Vol.3(1-2) 2004 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

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Effects of Varying Geometrical Parameters on Boiling From Microfabricated Enhanced Structures

Journal of Heat Transfer ◽

10.1115/1.1513575 ◽

2003 ◽

Vol 125 (1) ◽

pp. 103-109 ◽

Cited By ~ 52

Author(s):

C. Ramaswamy ◽

Y. Joshi ◽

W. Nakayama ◽

W. B. Johnson

Keyword(s):

Heat Dissipation ◽

Layer Structure ◽

Single Layer ◽

Nucleate Boiling ◽

Heat Fluxes ◽

Working Fluid ◽

Geometrical Parameters ◽

Small Range ◽

Two Phase ◽

Wall Superheat

The current study involves two-phase cooling from enhanced structures whose dimensions have been changed systematically using microfabrication techniques. The aim is to optimize the dimensions to maximize the heat transfer. The enhanced structure used in this study consists of a stacked network of interconnecting channels making it highly porous. The effect of varying the pore size, pitch and height on the boiling performance was studied, with fluorocarbon FC-72 as the working fluid. While most of the previous studies on the mechanism of enhanced nucleate boiling have focused on a small range of wall superheats (0–4 K), the present study covers a wider range (as high as 30 K). A larger pore and smaller pitch resulted in higher heat dissipation at all heat fluxes. The effect of stacking multiple layers showed a proportional increase in heat dissipation (with additional layers) in a certain range of wall superheat values only. In the wall superheat range 8–13 K, no appreciable difference was observed between a single layer structure and a three layer structure. A fin effect combined with change in the boiling phenomenon within the sub-surface layers is proposed to explain this effect.

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Revisiting the Bøggild Intergrowth in Iridescent Labradorite Feldspars: Ordering, Kinetics, and Phase Equilibria

Minerals ◽

10.3390/min11070727 ◽

2021 ◽

Vol 11 (7) ◽

pp. 727

Author(s):

Shiyun Jin ◽

Huifang Xu ◽

Seungyeol Lee

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Atom Probe ◽

Phase Region ◽

Two Phase ◽

Subsolidus Phase ◽

Plagioclase Feldspar ◽

X Ray ◽

Transmission Electron ◽

Scanning Transmission

The enigmatic Bøggild intergrowth in iridescent labradorite crystals was revisited in light of recent work on the incommensurately modulated structures in the intermediated plagioclase. Five igneous samples and one metamorphic labradorite sample with various compositions and lamellar thicknesses were studied in this paper. The lamellar textures were characterized with conventional transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The compositions of individual lamellae were analyzed with high-resolution energy-dispersive X-ray spectroscopy (EDS) mapping and atom probe tomography (APT). The average structure states of the studied samples were also compared with single-crystal X-ray diffraction data (SC-XRD). The Na-rich lamellae have a composition of An44–48, and the Ca-rich lamellae range from An56 to An63. Significant differences between the lamellar compositions of different samples were observed. The compositions of the Bøggild intergrowth do not only depend on the bulk compositions, but also on the thermal history of the host rock. The implications on the subsolidus phase relationships of the plagioclase feldspar solid solution are discussed. The results cannot be explained by a regular symmetrical solvus such as the Bøggild gap, but they support an inclined two-phase region that closes at low temperature.

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