Modeling and experimental study of the interface morphology and growth kinetics of fibrous eutectic solidification

2006 ◽  
Vol 21 (12) ◽  
pp. 3009-3016 ◽  
Author(s):  
X. Yao
Keyword(s):  
Growth Rate ◽  
Temperature Gradient ◽  
Scaling Law ◽  
Experimental Studies ◽  
High Growth ◽  
Eutectic Growth ◽  
Growth Front ◽  
Eutectic Solidification ◽  
Stable Range ◽  
Fixed Temperature

Experimental studies of fibrous eutectic growth in succinonitrile–camphor reveal that models of the stable range of interfibrous spacings must incorporate the dynamic effects and the instability of the growth front of the fibrous phase, which determines the fineness and regularity of the microstructures. An analytical mathematical model for fibrous eutectic growth has been developed and compared with the experimental results. The selected wavelength scales obey , where d0, ls, lt are the capillary, diffusion, and thermal lengths, respectively. While only at a relatively high growth rate or steep temperature gradient, the scaling law λ2V = constant is fulfilled. It is found that the selected band of interfibrous spacings is very narrow. This means that the interfibrous spacing is almost unique at a given growth rate and a fixed temperature gradient. The effects of convection on the interfibrous spacing selection and fibrous phase instability of short wavelength perturbations have also been investigated. These studies reveal that the controlled solidification of a fibrous eutectic produces a very fine and regular microstructure.

Numerical and experimental studies of high growth-rate over area with 1-inch in diameter under moderate input-power by using MWPCVD

2008 ◽  
Vol 17 (7-10) ◽  
pp. 1062-1066 ◽  
Author(s):  
Hideaki Yamada ◽  
Akiyoshi Chayahara ◽  
Yoshiaki Mokuno ◽  
Shin-ichi Shikata
Keyword(s):  
Growth Rate ◽  
Experimental Studies ◽  
High Growth ◽  
Input Power ◽  
High Growth Rate

Analysis of the high growth-rate transition in Al–Si eutectic solidification

2009 ◽  
Vol 44 (18) ◽  
pp. 4892-4899 ◽  
Author(s):  
T. Hosch ◽  
L. G. England ◽  
R. E. Napolitano
Keyword(s):  
Growth Rate ◽  
High Growth ◽  
High Growth Rate ◽  
Eutectic Solidification

Exploring SiC Growth Limitation of Vapor-Liquid-Solid Mechanism when Using Two Different Carbon Precursors

2013 ◽  
Vol 740-742 ◽  
pp. 323-326
Author(s):  
Kassem Alassaad ◽  
François Cauwet ◽  
Davy Carole ◽  
Véronique Soulière ◽  
Gabriel Ferro
Keyword(s):  
Growth Rate ◽  
High Growth ◽  
High Growth Rate ◽  
Carbon Precursor ◽  
Growth Limitation ◽  
Vapor Liquid Solid ◽  
Partial Pressures ◽  
Vapor Liquid Solid Mechanism ◽  
Vls Growth ◽  
Vapor Liquid

Abstract. In this paper, conditions for obtaining high growth rate during epitaxial growth of SiC by vapor-liquid-solid mechanism are investigated. The alloys studied were Ge-Si, Al-Si and Al-Ge-Si with various compositions. Temperature was varied between 1100 and 1300°C and the carbon precursor was either propane or methane. The variation of layers thickness was studied at low and high precursor partial pressure. It was found that growth rates obtained with both methane and propane are rather similar at low precursor partial pressures. However, when using Ge based melts, the use of high propane flux leads to the formation of a SiC crust on top of the liquid, which limits the growth by VLS. But when methane is used, even at extremely high flux (up to 100 sccm), no crust could be detected on top of the liquid while the deposit thickness was still rather small (between 1.12 μm and 1.30 μm). When using Al-Si alloys, no crust was also observed under 100 sccm methane but the thickness was as high as 11.5 µm after 30 min growth. It is proposed that the upper limitation of VLS growth rate depends mainly on C solubility of the liquid phase.

PHASE-FIELD MODELING OF ELASTIC EFFECTS IN EUTECTIC GROWTH WITH MISFIT STRESSES

2012 ◽  
Vol 04 (01) ◽  
pp. 1250024
Author(s):  
ZOHREH EBRAHIMI ◽  
JOAO REZENDEH
Keyword(s):  
Phase Field ◽  
Elastic Energy ◽  
Field Model ◽  
Phase Field Model ◽  
Solidification Process ◽  
Eutectic Growth ◽  
Point Of View ◽  
Eutectic Solidification ◽  
Elastic Model ◽  
Sharp Interface Model

Elastic interactions, arising from a difference of lattice spacing between two coherent phases in eutectic alloys with misfit stresses, can have an influence on microstructural pattern formation of eutectic colonies during solidification process. From a thermodynamic point of view the elastic energy contributes to the free energy of the phases and modifies their mutual stability. Therefore, the elastic stresses will have an effect on stability of lamellae, lamellae spacing and growth modes. In this paper, a phase-field model is employed to investigate the influence of elastic misfits in eutectic growth. The model reduces to the traditional sharp-interface model in a thin-interface limit, where the microscopic interface width is small but finite. An elastic model is designed, based on linear microelasticity theory, to incorporate the elastic energy in the phase-field model. Theoretical and numerical approaches, required to model elastic effects, are formulated and the stress distributions in eutectic solidification structures are evaluated. The two-dimensional simulations are performed for directed eutectic growth and the simulation results for different values of the misfit stresses are illustrated.

Very High Growth Rate of 4H-SiC Using MTS as Chloride-Based Precursor

2008 ◽  
Vol 600-603 ◽  
pp. 115-118 ◽  
Author(s):  
Henrik Pedersen ◽  
Stefano Leone ◽  
Anne Henry ◽  
Franziska Christine Beyer ◽  
Vanya Darakchieva ◽  
...  
Keyword(s):  
Growth Rate ◽  
Linear Dependence ◽  
Growth Rates ◽  
Molar Fraction ◽  
High Growth ◽  
High Growth Rate ◽  
Epitaxial Layers ◽  
Single Precursor ◽  
Very High

The chlorinated precursor methyltrichlorosilane (MTS), CH3SiCl3, has been used to grow epitaxial layers of 4H-SiC in a hot wall CVD reactor, with growth rates as high as 170 µm/h at 1600°C. Since MTS contains both silicon and carbon, with the C/Si ratio 1, MTS was used both as single precursor and mixed with silane or ethylene to study the effect of the C/Si and Cl/Si ratios on growth rate and doping of the epitaxial layers. When using only MTS as precursor, the growth rate showed a linear dependence on the MTS molar fraction in the reactor up to about 100 µm/h. The growth rate dropped for C/Si < 1 but was constant for C/Si > 1. Further, the growth rate decreased with lower Cl/Si ratio.

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