Impact of Thermal Transport on Silicon Carbide Formation/Engulfment During Directional Solidification of Si

2012 ◽  
Author(s):  
Xu Ma ◽  
Hui Zhang ◽  
Lili Zheng
Keyword(s):  
Directional Solidification ◽  
Carbon Concentration ◽  
Thermal Transport ◽  
Solidification Rate ◽  
Carbon Accumulation ◽  
Carbide Formation ◽  
Melt Convection ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Sic Particle

This paper investigates thermal transport on SiC formation and engulfment in directional solidification of crystalline Si. A comprehensive computational model is developed which is capable of describing fluid and thermal transport, SiC particle formation/transport, and its pushing-engulfment near the solidification interface. It is found that the impurity of carbon concentration in the melt is affected by melt convection; the concave interface leads to the carbon accumulation in the central region near the interface; the size of the SiC particle when engulfed into solid Si is mainly determined by the solidification rate. The distributions of carbon concentration and SiC particles are determined by both melt convection, interface shape and solidification rate. The low solidification rate is not desirable for high quality Si crystal growth when the solid/liquid interface is concave.

Equilibrium and Metastable Eutectics Near the Ni3Al Composition

2005 ◽  
Vol 486-487 ◽  
pp. 257-260
Author(s):  
Y. Lu ◽  
J.S. Lee ◽  
Je Hyun Lee ◽  
Dang Moon Wee ◽  
Myung Hoon Oh
Keyword(s):  
High Temperature ◽  
Directional Solidification ◽  
Solidification Rate ◽  
Eutectic Structure ◽  
Research Area ◽  
Solidification Behavior ◽  
Considerable Research ◽  
Increasing Temperature ◽  
Solid Liquid Interface ◽  
Solid Liquid

Ni3Al has been considerable research area due to its high temperature behavior increasing strength with increasing temperature. A series of directional solidification studies showed that the eutectic occurred between g’/b and the metastable eutectic of g/b forms under slightly different conditions, however, it is not well established whether the eutectic is composed of g/g‘, g’/b, or g/b . In order to understand solidification behavior of the eutectic structure, directional solidification experiments have been carried out with solidification rate near the Ni3Al composition in this study. The effects of the solidification rate and composition on formation of the equilibrium and metastable eutectics have been discussed. The (g’+g) coupled phase was also shown to form with the eutectic at the solid/liquid interface.

Formation of Ferrite with Cr Equivalents and Solidification Rates in Mod. (9-12)Cr-1Mo Steels

2007 ◽  
Vol 124-126 ◽  
pp. 1497-1500
Author(s):  
Y.H. Kim ◽  
H.C. Kim ◽  
Yeon Gil Jung ◽  
J.H. Lee ◽  
B.H. Chi ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Volume Fraction ◽  
Solidification Rate ◽  
Liquid Interface ◽  
Solidification Microstructure ◽  
Composition Change ◽  
Heat Treated ◽  
Solid Liquid Interface ◽  
Solid Liquid

The influence of solidification rates and Cr equivalents on the formation of the ferrite was studied by directional solidification in mod. (9-12)Cr-1Mo steels. It was found that the volume fraction of ferrite increased as increasing Cr equivalent and solidification rate. The volume fraction of the ferrite showed much higher at low solidification rates with the planar or cellular interface than that at high solidification rates with the dendritic interface. The volume fraction of ferrite in solidification microstructure showed much higher than that in extruded and heat-treated alloys. It depends on not only solidification rate and Cr equivalent but also the solidification fraction. At low solidification rates, there occurs segregation because the solid/liquid interface was planar or cellular, and it makes composition change with solidification fractions. The formation of ferrite has been discussed with Cr equivalent and solidification rate.

Microstructure Evolution with Solidification Rates in IN 738LC Superalloy

2006 ◽  
Vol 510-511 ◽  
pp. 450-453 ◽  
Author(s):  
H.C. Kim ◽  
Y.H. Kim ◽  
Yeon Gil Jung ◽  
Je Hyun Lee ◽  
Chang Yong Jo ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Morphological Evolution ◽  
Solidification Rate ◽  
Planar Interface ◽  
Interface Morphology ◽  
High Thermal Gradient ◽  
Solid Liquid Interface ◽  
Superalloy In738lc ◽  
Solid Liquid ◽  
Base Superalloy

The morphological evolution and growth mechanism of solidification interface with solidification rates were investigated in the Ni-base superalloy, IN738LC, by directional solidification and quenching technique under a relatively high thermal gradient of 20.5oC/mm. The planar interface of the MC-γ eutectic was found at the low solidification of 1 µm/s, and the dendritic interface formed above 5 µm/s. The dendrite lengths increased as increasing increasing solidification rate, and the dendrite tip temperature was close to the liquidus temperature at 50 µm/s. The carbide morphologies were blocky-type and rod-type in the planar interface of low solidification rates, and as the solidification rate increased, the carbide shape changed from script type to spotty type. The phase transformation temperatures from the dendrite to MC carbide and eutectic were estimated by DTA and by the solid/liquid interface morphology by directional solidification.

The Solidification Microstructure and Carbide Formation Behaviors in the Cobalt-Based Superalloy ECY768

2005 ◽  
Vol 486-487 ◽  
pp. 374-377 ◽  
Author(s):  
J.S. Lee ◽  
Je Hyun Lee ◽  
Baig Gyu Choi ◽  
Chang Yong Jo ◽  
Ung Yu Paik ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Base Alloy ◽  
Freezing Temperature ◽  
Solidification Microstructure ◽  
M23c6 Carbide ◽  
Carbide Formation ◽  
Eutectic Carbides ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Selection Of

Co-base superalloys have been applied in the stationary compoents of gas turbine owing to their excellent high temperaure properties. The stationary Co-base alloy components are generally manufactured by casting. Solidification behavior of the alloy is an important factor in the selection of casting parameters. In the present study, solidification microstructure and carbide formation behaviors were studied by directional solidification. Directional solidification experiments were carried out at the solidification rates of 0.5 ~ 150µm/s with the Co-base superalloy ECY768. Between the dendrites just below the final freezing temperature, MC carbide and M23C6 carbide were found. It was identified that the script or blocky carbides were Ta or W-rich MC carbide, and the lamellar carbides were Cr-rich M23C6 eutectic carbides. The solid/liquid interface morphology clearly showed that freezing of the Cr-rich eutectic carbide occurred just after the script type MC carbide.

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.

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.

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.

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