The convective effect on the morphological instability of KNbO3 crystals

Cai, Li Xia; Jin, Weiqing; Yoda, Shinichi; Zhang, Pan; Liang, Xinan; Liu, Z.H.

doi:10.1016/s0022-0248(01)01481-6

Cited by 7 publications

(4 citation statements)

References 8 publications

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“…Along with the dendrite growth, the component ratio in the melts in front of the interface (points II, III, IV) is gradually close to the stoichiometric concentration, which can be explained by the convective transfer effect. From point T to IV, the tip of the dendrite arrives at the diffusive-convective region, and the component ratio at point IV is close to the stoichiometric concentration, which illustrates that the convective transfer makes the concentration in the melts uniform [10] . However, as to the problem on how the heat transfer, mass transfer and momentum transfer affect the growth rate, structures and components in the dendrite growth, much more thorough work will be required.…”

Section: Resultsmentioning

confidence: 81%

In situ observation of NaBi(WO4)2 dendrite growth and the study on microstructure of solidification

Jin

et al. 2007

SCI CHINA SER G

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The dendrite growth process of transparent NaBi(WO 4 ) 2 with small prandtl and high melting point was studied by using the in-situ observation system. According to the dynamic images and detailed information, there are two kinds of restriction effect on the dendrite growth, the competition between arms and branches and the convection in the melt. The dendrite growth rate was time dependent, and the rate of arm growth reached the maximum 5.8 mm/s in the diffusive-advective region and rapidly decreased in the diffusive-convective region. The growth rate of branch had the same change trends as the arm's. Based on the EPMA-EDS data of solidification structure of quenched NaBi(WO 4 ) 2 melt, it was found that there were component differences from stoichiometric concentration in the melt near the interface during the growth process.oxide, dendrite, in-situ observation, solidification structure

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Section: Resultsmentioning

confidence: 81%

In situ observation of NaBi(WO4)2 dendrite growth and the study on microstructure of solidification

Jin

et al. 2007

SCI CHINA SER G

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“…Our previous works [5,6] have shown that, for oxide melt morphological instability will occur and skeletal or dendritic shape will be obtained during rapid growth. In this work, using an in situ observation system, we distinguished diffusive and convective effects on crystal morphological stability in case of high cooling rate.…”

Section: Introductionmentioning

confidence: 99%

Solute distribution in KNbO ₃ melt-solution and its effect on dendrite growth during rapid solidification

et al. 2009

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This paper reports that the rapid solidification of mixed Li 2 B 4 O 7 and KNbO 3 melted in a Pt loop heater has been performed experimentally by the method of quenching, and various morphologies of KNbO 3 crystals have been observed in different regions of the quenched melt-solution. Dendrites were formed in the central region where mass transfer is performed by diffusion, whereas polygonal crystals with smooth surface grew in the marginal region where convection dominates mass transport. Based on measurement of KNbO 3 concentration along crystal interface by electronic probe analysis, it finds the variety of crystal morphologies, which is the result of different solute distributions: in the central region the inhomogeneity of solute concentration is much sharper and morphological instability is easier to take place; nevertheless in the marginal region the concentration homogeneity has been greatly enhanced by convection which prevents the occurrence of morphological instability. Additional solute distribution in the melt along the primary dendrite trunk axis as well as that in mushy zones has also been determined. Results show that the solute concentration in the liquid increases linearly with distance from the trunk tip and more solutes were found to be concentrated in mushy zones. The closer the mushy zone is to trunk tip, the lower the solute concentration will be there.

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“…The effect of convective flow on dendritic growth under microgravity has been investigated during the past decades. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Huang and Glicksman [1] first carried out the important experimental investigation in the micro-gravity environment and found that buoyancy-driven convention has a profound effect on the growth speeds and the tip radii of the isolated dendrites. Rubinstein and Glicksman [3] found that dendrite growth velocity is an indication of the effect of interfacial energy anisotropy and buoyancy-driven convection.…”

Section: Introductionmentioning

confidence: 99%

“…Baumgartl et al [7] theoretically and experimentally studied the effect of buoyancy-driven convection and obtained a good correlation between the results of three-dimensional time-dependent numerical modeling, experimental modeling, and crystal growth of GaAs. Cai et al [9] concluded that the combinative effect of buoyancy and surface tension convection enhances the homogeneity of the solute concentration and thus their morphological stability. Basil et al [10] made numerical simulations as well as laboratory experiments of buoyancy-driven convection in an ampoule under varying heating and gravitational acceleration loadings and studied the nature and strength of the convective motion under low gravity conditions.…”

Section: Introductionmentioning

confidence: 99%

Effect of buoyancy-driven convection on steady state dendritic growth in a binary alloy

Chen

Wang

2013

Chinese Phys. B

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The effect of buoyancy-driven convection on the steady state dendritic growth in an undercooled binary alloy is studied. For the case of the moderate modified Grashof number, the uniformly valid asymptotic solution in the entire region of space is obtained by means of the matched asymptotic expansion method. The analytical results show that the buoyancydriven convection has a significant effect on the needle-like interface of dendritic growth. Due to the buoyancy-driven convection, the needle-like interface shape of the crystal is changed. When the Peclet number that is not affected by the buoyant flow is less than a certain critical value, the interface shape of the dendrite becomes thinner as the Grashof number increases; when it is larger than the critical value, the interface shape becomes fatter as the Grashof number increases. In the undercooled binary alloy the morphology number plays an active role in the interface shape and leads to the buoyancy effect that is different from the situation for the pure melt. The smaller the morphology number is, the more significant change the interface shape has. As the Peclet number further increases, the effect of buoyancy on the interface diminishes eventually.

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The convective effect on the morphological instability of KNbO3 crystals

Cited by 7 publications

References 8 publications

In situ observation of NaBi(WO4)2 dendrite growth and the study on microstructure of solidification

In situ observation of NaBi(WO4)2 dendrite growth and the study on microstructure of solidification

Solute distribution in KNbO ₃ melt-solution and its effect on dendrite growth during rapid solidification

Effect of buoyancy-driven convection on steady state dendritic growth in a binary alloy

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The convective effect on the morphological instability of KNbO3 crystals

Cited by 7 publications

References 8 publications

In situ observation of NaBi(WO4)2 dendrite growth and the study on microstructure of solidification

In situ observation of NaBi(WO4)2 dendrite growth and the study on microstructure of solidification

Solute distribution in KNbO 3 melt-solution and its effect on dendrite growth during rapid solidification

Effect of buoyancy-driven convection on steady state dendritic growth in a binary alloy

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Solute distribution in KNbO ₃ melt-solution and its effect on dendrite growth during rapid solidification