scholarly journals Investigation of Peritectic Solidification Morphologies by Using the Binary Organic Model System TRIS-NPG

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 966
Author(s):  
Johann P. Mogeritsch ◽  
Mehran Abdi ◽  
Andreas Ludwig
Keyword(s):  
Growth Conditions ◽  
Model System ◽  
Process Conditions ◽  
Competitive Growth ◽  
Diffusive Growth ◽  
Β Phase ◽  
Α Phase ◽  
Peritectic Solidification ◽  
Solid Liquid Interface ◽  
Solid Liquid

Under pure diffusive growth conditions, layered peritectic solidification is possible. In reality, the competitive growth of the primary α-phase and the peritectic β-phase revealed some complex peritectic solidification morphologies due to thermo-solutal convection. The binary organic components Tris-(hydroxylmenthyl) aminomethane-(Neopentylglycol) were used as a model system for metal-like solidification. The transparency of the high-temperature non-faceted phases allows for the studying of the dynamic of the solid/liquid interface that lead to peritectic solidification morphologies. Investigations were carried out by using the Bridgman technic for process conditions where one or both phases solidify in a non-planar manner. Different growth conditions were observed, leeding to competitive peritectic growth morphologies. Additionally, the competitive growth was solved numerically to interpret the observed transparent solidification patterns.

scholarly journals Investigation on Peritectic Solidification Morphologies by Using the Binary Organic Model System TRIS-NPG

2020 ◽  
Author(s):  
Johann P. Mogeritsch ◽  
Mehran Abdi ◽  
Andreas Ludwig
Keyword(s):  
Beta Phase ◽  
Growth Conditions ◽  
Model System ◽  
Process Conditions ◽  
Competitive Growth ◽  
Solutal Convection ◽  
Diffusive Growth ◽  
Peritectic Solidification ◽  
Solid Liquid Interface ◽  
Solid Liquid

Under pure diffusive growth conditions, layered peritectic solidification is possible. In reality, the competitive growth of the primary alfa-phase and the peritectic beta-phase revealed some complex peritectic solidification morphologies due to thermo-solutal convection. The binary organic components TRIS-NPG were used as model system for metal-like solidification. The transparency of the high-temperature non-faceted phases allows studying the dynamic of the solid/liquid interface which lead to peritectic solidification morphologies. Investigations were carried out by using the Bridgman technic for process conditions where one or both phases solidify in a non-planar manner. Different growth conditions were observed which led to competitive peritectic growth morphologies. Additionally, the competitive growth was solved numerically to interpret the observed transparent solidification patterns.

scholarly journals Diffusive steel scrap melting in carbon-saturated hot metal—phenomenological investigation at the solid–liquid interface

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1358 ◽  
Author(s):  
Penz ◽  
Schenk ◽  
Ammer ◽  
Klösch ◽  
Pastucha ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Carbon Concentration ◽  
Steel Production ◽  
Production Optimization ◽  
Steel Scrap ◽  
Process Conditions ◽  
Hot Metal ◽  
Scrap Melting ◽  
Solid Liquid Interface ◽  
Solid Liquid

The oxygen steelmaking process in a Linz-Donawitz (LD) converter is responsible for more than 70% of annual crude steel production. Optimization of the process control and numerical simulation of the LD converter are some of the current challenges in ferrous metallurgical research. Because of the process conditions and oxidation of impurities of the hot metal, a lot of chemical heat is generated. Therefore, steel scrap is charged as a coolant with the economical side aspect of its recycling. One of the more complex aspects is, among others, the dissolution and melting behaviour of the scrap in carbon-saturated hot metal. Heat and mass transfer act simultaneously, which has already been investigated by several researchers using different experimental approaches. The appearances at the interface between solid steel and liquid hot metal during diffusive scrap melting have been described theoretically but never investigated in detail. After an experimental investigation under natural and forced convective conditions, the samples were further investigated with optical microscopy and electron probe microanalysis (EPMA). A steep carbon concentration gradient in the liquid appeared, which started at an interface carbon concentration equal to the concentration on the solid side of the interface. Moreover, the boundary layer thickness moved towards zero, which symbolized that the boundary layer theory based on thermodynamic equilibrium was not valid. This fact was concluded through the prevailing dynamic conditions formed by natural and forced convection.

Structural Properties of β-FeSi2 Bulk Crystal Grown by Horizontal Gradient Freeze Method

1995 ◽  
Vol 402 ◽  
Author(s):  
H. Kakemoto ◽  
Y. Tsaic ◽  
A. C. Beye ◽  
H. Katsumata ◽  
S. Sakuragi ◽  
...  
Keyword(s):  
High Purity ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Growth Conditions ◽  
Horizontal Gradient ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Α Phase ◽  
Micro Analysis

AbstractWe report on the synthesis of β-FeSi2 bulk materials using Horizontal Gradient Freeze (HGF) method. Chunk and powder FeSi2 or high-purity Fe (4N) and Si (9N) were used as starting materials. Three values (1:2, 2:5 and 1:3) of the Fe:Si ratio were selected in the very narrow α and β ranges of the equilibrium phase diagram. Samples were melted between 1300°C and 1500°C in high purity graphite crucibles covered with boron nitride. After cooling, the samples were kept at 800°C and 900°C during 66 to 100 hours, leading to transformation from α to β phase. Cooling rate and annealing time were taken as the two main parameters to optimize the growth conditions. Principal structural characterization was made by X-ray diffraction (XRD). Correlation with stoichiometry was achieved using the results of Rutherford Backscattering Spectroscopy (RBS) and Electron Probe X-Ray Micro Analysis (EPXMA). The samples obtained from 1:2 ratio exhibited mainly β phase while the 2:5 ratio specimens revealed almost α phase structure. The samples prepared with 1:3 ratio was found as a mixture of α and β phases under Si-rich conditions.

THE EFFECT OF GROWTH CONDITIONS UPON THE SOLIDIFICATION OF A BINARY ALLOY

1956 ◽  
Vol 34 (1) ◽  
pp. 96-121 ◽  
Author(s):  
W. A. Tiller ◽  
J. W. Rutter
Keyword(s):  
Binary Alloy ◽  
Impurity Content ◽  
Growth Conditions ◽  
Orientation Dependence ◽  
Liquid Interface ◽  
Critical Ratio ◽  
Liquid Lead ◽  
Careful Study ◽  
Solid Liquid Interface ◽  
Solid Liquid

This investigation provides both a theoretical and an experimental analysis of the factors which affect the mode of solidification of a binary alloy. These factors are: (i) the concentration of solute in the melt (C0); (ii) the rate of solidification (R); (iii) the temperature gradient in the melt at the solid–liquid interface (G). Extremely high purity lead was produced by zone refining and, from this material, crystals containing known concentrations of tin, silver, and gold were grown under a range of well-controlled growth conditions. The mode of solidification was investigated by a careful study of the change in appearance of the solid–liquid interface with a change in growth conditions. For a crystal containing a specific C0 of solute it was observed that (a) the transition from a smooth interface to a cellular interface occurred at a critical ratio of G to R; (b) the width of the cells varied inversely as G and inversely as R; (c) the transition from a cellular interface to a dendritic interface exhibited a large orientation dependence, and for a constant orientation breakdown occurred at a critical ratio of G to [Formula: see text]. The experimental observations confirm both the existence of a solute-rich layer of liquid adjacent to the solid-liquid interface and its quantitative features. From this agreement with theory the diffusion coefficients of tin, silver, and gold in liquid lead at 327 °C. are determined. This work serves to illustrate the effect of extremely small amounts of particular solutes upon the development of substructures during solidification. A technique is proposed for obtaining a measure of the purity of low impurity content alloys.

Effects of Geometric Constraint on Solidification Microstructural Development of Peritectic TiAl Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 1147-1152
Author(s):  
S. Zhang ◽  
M.J.M. Krane ◽  
David R. Johnson
Keyword(s):  
Growth Front ◽  
Microstructural Development ◽  
Thin Sections ◽  
Tial Alloys ◽  
Β Phase ◽  
Tracking Model ◽  
State Growth ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Tip Radius

Directional solidification of binary peritectic TiAl alloys through preforms with straight channels with spacing on the order of the dendritic tip radius were simulated using a modified solid-liquid interface tracking model. Interruption of the steady-state growth of the primary β-phase by constraint of solutal diffusion within very thin sections of ceramic preforms can lead to solidification conditions favorable for the nucleation and continued growth of the peritectic α-phase even after the growth front has exited the preform.

scholarly journals Analysis of Solid-Liquid Interface Behavior during Continuous Strip-Casting Process Using Sharp-Interface Technique

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Changbum Lee ◽  
Wooyoung Yoon ◽  
Seungwon Shin ◽  
Jaewoo Lee ◽  
Hee-eun Song
Keyword(s):  
Liquid Interface ◽  
Strip Casting ◽  
Sharp Interface ◽  
Optimum Process ◽  
Process Conditions ◽  
Reconstruction Method ◽  
Interface Behavior ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Continuous Strip

Continuous strip casting (CSC) has been developed to fabricate thin metal plates while simultaneously controlling the microstructure of the product. A numerical analysis to understand the solid-liquid interface behaviors during CSC was carried out and used to identify the solidification morphologies of the plate, which were then used to obtain the optimum process conditions. In this study, we used a modified level contour reconstruction method and the sharp-interface method to modify the interface tracking, and we performed a simulation analysis to identify the differences in the material properties that affect the interface behavior. The effects of the process parameters such as the heat transfer coefficient and extrusion velocity on the behavior of the solid-liquid interface are estimated and also used to improve the CSC process.

GROWTH CONDITIONS FOR STABILITY OF A CELLULAR SOLID-LIQUID INTERFACE

1957 ◽  
Vol 35 (10) ◽  
pp. 1223-1227 ◽  
Author(s):  
E. L. Holmes ◽  
J. W. Rutter ◽  
W. C. Winegard
Keyword(s):  
Freezing Temperature ◽  
Growth Conditions ◽  
Solute Concentration ◽  
Critical Value ◽  
Liquid Interface ◽  
Cellular Solid ◽  
First Approximation ◽  
Comparison Of The Results ◽  
Solid Liquid Interface ◽  
Solid Liquid

Samples of zone-refined lead containing various amounts of silver as solute were solidified under well-controlled conditions to study the transition from cellular to dendritic freezing as a function of composition, speed of freezing, temperature gradient in the melt during freezing, and crystallographic orientation of the solidifying crystal. A comparison of the results of this investigation with those of Tiller and Rutter (1956) on alloys of tin in lead shows that to a first approximation the onset of dendritic freezing under any given growth conditions occurs at a critical value of the average solute concentration in the liquid at the solid–liquid interface, independent of whether the solute present is tin or silver.

Microstructures Observed during Directional Solidification along the Univariant Eutectic Reaction in a Ternary Al-Cu-Si Alloy

2006 ◽  
Vol 508 ◽  
pp. 51-56 ◽  
Author(s):  
Jimmy De Wilde ◽  
Ludo Froyen
Keyword(s):  
Growth Velocity ◽  
Eutectic Reaction ◽  
Interlamellar Spacing ◽  
Liquid Interface ◽  
Ternary Alloys ◽  
Competitive Growth ◽  
Two Phase ◽  
The Stability ◽  
Solid Liquid Interface ◽  
Solid Liquid

Within the frame of the ESA research program SETA, “Solidification along a Eutectic Path in Ternary Alloys”, experiments have been performed focussing on several distinct subtopics. One of these subtopics is to study coupled growth along the univariant eutectic reaction: L → α + β. In this paper, the influence of the growth velocity v on the morphology of the solid/liquid interface is evaluated in a ternary Al-Cu-Si alloy with a composition close to the univariant eutectic groove L → α(Al) + θ-Αl2Cu. Different structural regions can be identified in terms of the stability of the solid-liquid interface (morphological stability) and the stability of the coupling (competitive growth) during unidirectional solidification as function of the solidification parameters. It is found that two-phase planar growth with a lamellar arrangement can be obtained at a sufficiently low growth rate v. The measured interlamellar spacing follows the Jackson and Hunt relationship λ2v = constant. At a higher growth velocity first a destabilisation of the solid/liquid interface is observed and finally competitive growth is observed revealing primary θ-Al2Cu growing ahead of the eutectic interface. It is assumed that the cellular break-up is a two-step process related to the crystallography of the system. Fitting the different morphologies into one microstructure map, an extension of the coupled zone concept as has been proposed for binary alloys is necessary.

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