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

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.

2017 ◽  
Vol 114 (44) ◽  
pp. 11627-11632 ◽  
Author(s):  
Ran Drori ◽  
Miranda Holmes-Cerfon ◽  
Bart Kahr ◽  
Robert V. Kohn ◽  
Michael D. Ward

The growth dynamics of D2O ice in liquid H2O in a microfluidic device were investigated between the melting points of D2O ice (3.8 °C) and H2O ice (0 °C). As the temperature was decreased at rates between 0.002 °C/s and 0.1 °C/s, the ice front advanced but retreated immediately upon cessation of cooling, regardless of the temperature. This is a consequence of the competition between diffusion of H2O into the D2O ice, which favors melting of the interface, and the driving force for growth supplied by cooling. Raman microscopy tracked H/D exchange across the solid H2O–solid D2O interface, with diffusion coefficients consistent with transport of intact H2O molecules at the D2O ice interface. At fixed temperatures below 3 °C, the D2O ice front melted continuously, but at temperatures near 0 °C a scalloped interface morphology appeared with convex and concave sections that cycled between growth and retreat. This behavior, not observed for D2O ice in contact with D2O liquid or H2O ice in contact with H2O liquid, reflects a complex set of cooperative phenomena, including H/D exchange across the solid–liquid interface, latent heat exchange, local thermal gradients, and the Gibbs–Thomson effect on the melting points of the convex and concave features.


2016 ◽  
Vol 16 (1) ◽  
pp. 124-130 ◽  
Author(s):  
M. Trepczyńska-Łent ◽  
E. Olejnik

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.


2012 ◽  
Vol 110 (2) ◽  
pp. 443-451 ◽  
Author(s):  
Dongmei Liu ◽  
Xinzhong Li ◽  
Yanqing Su ◽  
Jingjie Guo ◽  
Liangshun Luo ◽  
...  

2007 ◽  
Vol 546-549 ◽  
pp. 1447-1450 ◽  
Author(s):  
Yan Qing Su ◽  
Chang Liu ◽  
Xin Zhong Li ◽  
Jing Jie Guo ◽  
Heng Zhi Fu

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.


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

2011 ◽  
Vol 675-677 ◽  
pp. 109-112
Author(s):  
Shu Ang Shi ◽  
Wei Dong ◽  
Shi Hai Sun ◽  
Yi Tan ◽  
Guo Bin Li ◽  
...  

The distribution of resistivity, impurity and polarity in multicrystalline silicon ingot prepared by directional solidification method was detected. The effect of impurity distribution on resistivity was also researched. The results show that the shapes of equivalence line of resistivity in the cross section and vertical section of the silicon ingot depend on the solid-liquid interface. The resistivity in the vertical section increases with the increasing of solidified height at the beginning of solidification and reaches to maximum at the polarity transition point, then decreases rapidly with the increasing of solidified height and tends to zero on the top of the ingot because of the high impurity concentration. Study proves that the variation of resistivity in the vertical section is mainly relevant to the concentration distribution of the impurities such as Al, B and P in the growth direction.


2019 ◽  
Vol 142 (1) ◽  
Author(s):  
J. B. Allen

In this work, we develop one- and two-dimensional phase-field simulations to approximate dendritic growth of a binary Al–2 wt% Si alloy. Simulations are performed for both isothermal as well as directional solidification. Anisotropic interface energies are included with fourfold symmetries, and the dilute alloy assumption is imposed. The isothermal results confirm the decrease in the maximum concentration for larger interface velocities as well as reveal the presence of parabolic, dendrite tips evolving along directions of maximum interface energy. The directional solidification results further confirm the formation of distinctive secondary dendritic arm structures that evolve at regular intervals along the unstable solid/liquid interface.


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