Oscillatory Instabilities in Cellular Solidification

1990 ◽  
Vol 43 (5S) ◽  
pp. S56-S58 ◽  
Author(s):  
K. Brattkus
Keyword(s):  
Directional Solidification ◽  
Absolute Stability ◽  
Symmetric Model ◽  
Solid Diffusion ◽  
Long Wave ◽  
Spatially Periodic ◽  
The Stability ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Oscillatory Instabilities

We adapt the recent derivation of a long-wave evolution equation for a solid-liquid interface undergoing directional solidification near the limit of absolute stability to the case of a symmetric model that includes solid diffusion. The stability of steady and spatially periodic solutions are investigated and it is found that these cellular solutions are subject to an oscillatory instability with twice the wavenumber of the underlying pattern. We discuss this instability in the context of experiments on the directional solidification of nematic liquid crystals.

On long-wave morphological instabilities in directional solidification

1995 ◽  
Vol 6 (6) ◽  
pp. 639-652 ◽  
Author(s):  
A. C. Skeldon ◽  
G. B. McFadden ◽  
M. D. Impey ◽  
D. S. Riley ◽  
K. A. Cliffe ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Wave Equations ◽  
Numerical Study ◽  
Liquid Interface ◽  
Interface Morphology ◽  
Binary Liquid ◽  
Long Wave ◽  
Morphological Instabilities ◽  
Solid Liquid Interface ◽  
Solid Liquid

A binary liquid that undergoes directional solidification is susceptible to morphological instabilities which cause the solid/liquid interface to change from a planar to a cellular state. This paper presents a numerical study of a class of long-wave equations that describe the evolution of interface morphology. We find new bifurcation points, new solution branches, and the existence of inverted hexagonal nodes and cells.

Stability of Solid/Liquid Interface of Pb-80wt%Sn Alloy under Direct Current during Directional Solidification

2013 ◽  
Vol 313-314 ◽  
pp. 245-248
Author(s):  
Ning Li ◽  
Rong Zhang ◽  
Li Min Zhang ◽  
Li Fei Du ◽  
Qian Liu
Keyword(s):  
Growth Rate ◽  
Directional Solidification ◽  
Direct Current ◽  
Liquid Interface ◽  
Density Current ◽  
Medium Density ◽  
Morphological Stability ◽  
The Stability ◽  
Solid Liquid Interface ◽  
Solid Liquid

The effect of medium-density current on the morphological stability of S/L interface of Pb-80wt%Sn alloy during directional solidification was investigated. The results indicated that both the DC of positive and negative 200 Acm-2 could decrease the critical growth rate of cellular/dendrite transition and minish the range of growth rate of cellular crystal. DC accelerated the microstructure transition from cellular crystal to dendrite crystal at the same pulling rate. Furthermore, the dendrite crystal was refined by positive and negative DC at high pulling rate. The effect of direction of DC to the microstructure transition could be neglected. In conclusion, the positive and negative 200 Acm-2 decreased the stability of solid/liquid interface of Pb-80%Sn alloy, and the lower the pulling rate was applied, the more obviously DC affected the microstructure.

Spatial Profile of Thermoelectric Effects During Peltier Pulsing in Bi and Bi/MnBi Eutectic

1986 ◽  
Vol 87 ◽  
Author(s):  
R. P. Silberstein ◽  
D. J. Larson
Keyword(s):  
Directional Solidification ◽  
Joule Heating ◽  
Current Density ◽  
Peltier Effect ◽  
Thomson Effect ◽  
Thermoelectric Effects ◽  
Spatial Profile ◽  
Thermal Transients ◽  
Solid Liquid Interface ◽  
Solid Liquid

AbstractWe have studied the spatial profile of the thermal transients that occur during and following the current pulsing associated with Peltier Interface Demarcation during directional solidification. Results for pure Bi are presented in detail and compared with corresponding results for the Bi/MnBi eutectic. Significant thermal transients occur throughout the sample that can be accounted for by the Peltier effect, the Thomson effect, and Joule heating. We have separated these effects and studied their behavior as a function of time, current density, and position with respect to the solid/liquid interface.

scholarly journals Solidification Front of Oriented Ledeburite

2016 ◽  
Vol 16 (1) ◽  
pp. 124-130 ◽  
Author(s):  
M. Trepczyńska-Łent ◽  
E. Olejnik
Keyword(s):  
Directional Solidification ◽  
Solidification Front ◽  
Liquid Interface ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Interface Structures

Abstract Directional solidification of the Fe - 4,3 wt % C alloy was performed with the pulling rate equal to v=83 μm/s. Sample was frozen during solidification to reveal the shape of the solid/liquid interface. Structures eutectic pyramid and spherolitic eutectic were observed. The solidification front of ledeburite eutectic was revealed. The leading phase was identified and defined.

Influence of initial solid–liquid interface morphology on further microstructure evolution during directional solidification

2012 ◽  
Vol 110 (2) ◽  
pp. 443-451 ◽  
Author(s):  
Dongmei Liu ◽  
Xinzhong Li ◽  
Yanqing Su ◽  
Jingjie Guo ◽  
Liangshun Luo ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Microstructure Evolution ◽  
Liquid Interface ◽  
Interface Morphology ◽  
Solid Liquid Interface ◽  
Solid Liquid

Microstructure Evolution of Ti-Al Peritectic System during the Initiated Stage of Directional Solidification

2007 ◽  
Vol 546-549 ◽  
pp. 1447-1450 ◽  
Author(s):  
Yan Qing Su ◽  
Chang Liu ◽  
Xin Zhong Li ◽  
Jing Jie Guo ◽  
Heng Zhi Fu
Keyword(s):  
Steady State ◽  
Directional Solidification ◽  
Microstructure Evolution ◽  
Aluminum Content ◽  
Solid Phase ◽  
Tial Alloys ◽  
Transient Stage ◽  
Set Up ◽  
Solid Liquid Interface ◽  
Solid Liquid

The microstructure evolution of Ti-Al peretectic system in transient stage and steady state in directional solidification was predicted via theoretical analysis. The solute distribution controlled by diffusion at and ahead the solid-liquid interface will determine whether the properitectic and peritectic phases can nucleate and grow ahead of the opposing solid phase. The formation of banding structure is possible in a certain composition range. At the steady state, a microstructure selection map was set up based on interface response function model. The microstructure of TiAl alloys with different aluminum content was studied with Bridgman directional solidification method. Some evidence in the experiment has been found to support the theoretical prediction.

Effect of Heating Temperature on Microstructure of Directionally Solidified Ni-43Ti-7Al Alloy

2017 ◽  
Vol 898 ◽  
pp. 552-560 ◽  
Author(s):  
Lei Zhou ◽  
Li Jing Zheng ◽  
Hu Zhang
Keyword(s):  
Volume Fraction ◽  
Heating Temperature ◽  
Thermal Gradients ◽  
Directionally Solidified ◽  
Melt Structure ◽  
Cast Sample ◽  
The Stability ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Liquid Metal Cooling

By liquid metal cooling (LMC) process, the Ni-43Ti-7Al (at.%) alloy has been directionally solidified (DS) at different heating temperatures (1450°C, 1550°C, 1650°C) and a constant withdrawal rate of 100μm/s. The results showed that anomalous eutectic structures which consisted of Ti2Ni and TiNi phases were formed at the grain boundaries of as-cast sample and similar structures were also observed in the intercellular regions of DS samples. However, the microstructure changed from the equiaxial structure to the cellular structure due to the axial thermal gradients imposed. After DS, the NiTi and Ti2Ni phases preferentially grew along certain orientation, but the preferred crystallographic orientations of them changed as the heating temperature increased to 1650°C, which might be related to the change of melt structure. As expected, the volume fraction of Ti2Ni increased from 3.3% to 5.2% and the cellular spacing decreased from 47.8μm to 27.0μm as heating temperature increased. In addition, the stability of solid/liquid interface decreased, resulting from the coupling effects of G and ΔT- with the heating temperature increasing.

In-situ observation of solid-liquid interface during directional solidification of succinonitrile and pivalic acid

2005 ◽  
Vol 16 (1-4) ◽  
pp. 107-110
Author(s):  
A. P. Shpak ◽  
O. P. Fedorov ◽  
E. L. Zhivolub ◽  
Y. J. Bersudskyy ◽  
O. V. Shuleshova
Keyword(s):  
Directional Solidification ◽  
Pivalic Acid ◽  
Liquid Interface ◽  
In Situ Observation ◽  
Solid Liquid Interface ◽  
Solid Liquid
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