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130 results on '"Jie, Wan-qi"'

41. Crystallization of Spherical Single Crystal of Silicon from Undercooled Droplet under Containerless Processing

Author

Jian, Zeng Yun, Jie, Wan Qi, and Kuribayashi, Kazuhiko

Subjects
Materials science, Silicon, Condensed matter physics, Mechanical Engineering, chemistry.chemical_element, Condensed Matter Physics, law.invention, Crystal, Crystallography, chemistry, Mechanics of Materials, law, General Materials Science, Crystallization, Supercooling, Single crystal
Abstract

The images of the growing crystal in the growth process of the undercooled droplets of silicon were lively recorded by using a high-speed camera. The number of crystal that nucleated spontaneously from the undercooled liquid was found to decrease to 1 when the undercooling was higher than 5K. The morphology of the growing single crystal of silicon was a thin plate. A model for predicting the critical undercooling of growing single crystal of silicon from undercooled liquid has been developed. The theoretically predicted value of the undercooling from present model for silicon is in agreement with the experimentally measured result.

Published
2005

43. Solute redistribution in the initial transient region of directional solidification specimen

Author

Jie Wan-qi and Ma Dong

Subjects
Temperature gradient, Planar, Materials science, Coupling effect, Thermal, General Physics and Astronomy, Redistribution (chemistry), Mechanics, Kinematics, Mass transportation, Directional solidification
Abstract

The solute redistribution during initial transient process of directional solidification of a binary alloy is associated with the solid-liquid interface advancing velocity which will pass a hysteretic process approaching to the externally imposed velocity. In the present paper, a new accelerated growth equation, dV/dt = μG[m/G dG*L/dt + Ve - V] is deduced, based on which a new formula for the initial transient solute redistribution is obtained with the reasonable assumption that the solid-liquid interface advancing velocity changes exponentially during solidification. It shows that the kinematic effect dominates solidification at high velocity while the coupling effect of thermal and mass transportation controls that at lower velocity. In addition, another new equation to calculate the time required for a planar interface to lose stability is also found. Since the effects of the imposed thermal gradient are taken into account in the new equations, they are more reasonable and satisfactory than those given by Tiller et al. and by Smith et al.

Published
1996

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