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| FORMATION AND EVOLUTION OF THE NON-DENDRITIC MORPHOLOGY IN UNDERCOOLING MELT WITH LOWER SHEARING RATE |
| ZHAO Lining, LIN Xin, HUANG Weidong |
| State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072 |
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Cite this article:
ZHAO Lining LIN Xin HUANG Weidong. FORMATION AND EVOLUTION OF THE NON-DENDRITIC MORPHOLOGY IN UNDERCOOLING MELT WITH LOWER SHEARING RATE. Acta Metall Sin, 2011, 47(4): 403-409.
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Abstract With the development of the semisolid metal processing technology, many efforts have been made to understand the relationship of the microstructural evolution with the shear rate and the melt undercooling. The globular and rosette microstructures can be obtained under the different shearing rates and melt undercooling. Since the microstructure evolves rapidly under the general high shearing rate in the previous researches, it is difficult to reveal the formation process of semisolid microstructure in detail. In this work, the evolutions of globular and rosette crystals were studies by using a transparent organic alloy Succinonitrile-5%H2O (molar fraction) with a small shearing rate. It is found that there is a critical value of the shearing rate in the semisolid process above which the morphology of the globular crystal could be stable and below which it would be destabilized to form equiaxed dendrite. In addition, when the interface lost the stability, the globular crystals will evolve to dendrite under a higher melt undercooling and to rosette under a lower undercooling. The continuous splitting of the tip of the perturbation cells in the globular crystal induces the formation of the rosette morphology.
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Received: 06 October 2010
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| Fund: Supported by National Natural Science Foundation of China (No.50771083) and Fund of the State Key Laboratory of Solidification Processing (NWPU) (No.02-TZ-2008) |
| About author: HUANG Weidong |
| [1] Spencer D B, Mehrabian R, Flemings M C. Metall Trans, 1972; 3A: 1925 [2] Flemings M C. Metall Trans, 1991; 22B: 957[3] Vogel R A, Cantor B. J Cryst Growth, 1977; 37: 309[4] Vogel A, Doherty R D, Cantor B. Proc Conf on Solidification and Casting of Metals, Sheffield, 1977, London: Metal Society, 1977: 518[5] Vogel A. Met Sci, 1978; 12: 576[6] Molenaar J M M, Salemans F W H C, Katgerman L. J Mater Sci, 1985; 20: 4335[7] Doherty R D. Met Sci, 1982; 16: 1[8] Mullis A M. Acta Mater, 1999; 47: 1783[9] Ji S, Fan Z. Metall Mater Trans, 2002; 33A: 3511[10] Li T, Huang W D, Lin X. Chin J Nonferrous Met, 2000; 10: 635(李涛, 黄卫东, 林 鑫. 中国有色金属学报, 2000; 10: 635)[11] Lin X, Li T, Huang W D. Solid State Phenom, 2006; 16–17: 155[12] Li T, Lin X, Huang W D. Acta Mater, 2006; 54: 481[13] Ji S, Fan Z, Bevis M J. Mater Sci Eng, 2001; A299: 210[14] Martinez R A, Flemings M C. Metall Mater Trans, 2005; 36A: 2205[15] Li T. PhD Thesis, Northwestern Polytechnical Universty, Xi’an, 2003(李涛. 西北工业大学博士学位论文. 西安, 2003)[16] Bian X F, Wang W M, Li H, Ma J J. The Melt Structure of Metal. Shanghai: ShangHai Jiao Tong University Press, 2003: 39(边秀房, 王伟民, 李 辉, 马家骥. 金属熔体结构. 上海: 上海交通大学出版社, 2003: 39)[17] Min N B. The Physical Fundamental of Crystal Growth. Shanghai: Shanghai Science and Technology Press, 1981: 226(闵乃本. 晶体生长的物理基础. 上海: 上海科学技术出版社, 1981: 226) |
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