Abstract This paper reports that the rapid solidification of mixed Li2B4O7 and KNbO3 melted in a Pt loop heater has been performed experimentally by the method of quenching, and various morphologies of KNbO3 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 KNbO3 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.
Received: 12 August 2008
Revised: 27 August 2008
Accepted manuscript online:
PACS:
68.70.+w
(Whiskers and dendrites (growth, structure, and nonelectronic properties))
Fund: Project
supported by the National Natural Science Foundation of China (Grant
Nos 50331040 and 50802105) and the Innovation Funds from Shanghai
Institute of Ceramics, Chinese Academy of Sciences (Grant No
SCX0623).
Cite this article:
Pan Xiu-Hong(潘秀红), Jin Wei-Qing(金蔚青), Liu Yan(刘岩), and Ai Fei(艾飞) Solute distribution in KNbO3 melt-solution and its effect on dendrite growth during rapid solidification 2009 Chin. Phys. B 18 699
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