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铁道科学与工程学报

JOURNAL OF RAILWAY SCIENCE AND ENGINEERING

Vol. 14    No. 6    December 2004

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Phase-field simulation of dendritic sidebranching induced by thermal noise
ZHU Chang-sheng(朱昌盛)1, 2, WANG Zhi-ping(王智平)1
JING Tao(荆 涛)3,  LIU Bai-cheng(柳百成)3

1. CAD Center, Lanzhou University of Technology, Lanzhou 730050, China;
2. State Key Laboratory of Gansu New Nonferrous Metal Materials,
Lanzhou University of Technology, Lanzhou 730050,  China;
 3. Department of Mechanical Engineering, Tsinghua University, 
Beijing 100084, China

Abstract: The influence of undercooling and noise magnitude on dendritic sidebranching during crystal growth was investigated by simulation of a phase-field model which incorporates thermal noise. It is shown that, the sidebranching is not influenced with inclusion of the nonconserved noise, therefore, in order to save the computational costs it is often neglected; while conserved noise drives the morphological instability and is dominant origin of sidebranching. The dependence of temperature field on magnitude of thermal noise is apparent, when Fu gets an appropriate value, noise can induce sidebranching but not influence the dendritic tip operating state. In the small undercooled melt, the thermal diffusion layer collected around the dendrite is thick, which suppresses the growth of its sidebranching and makes the dendrite take on the morphology of no sidebranching, but when the undercooling is great, the thermal diffusion layer is thin, which is advantageous to the growth of the sidebranching and the dendrite presents the morphology of the developed sidebranching.

 

Key words:  Phase-field method; undercooling; thermal noise; dendritic sidebranching; numerical simulation

ISSN 1672-7029
CN 43-1423/U

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