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In directional solidification, two characteristic parameters determine the dendritic growth: the thermal gradient and the pulling velocity. To achieve the suitable microstructure and improve the performance of casting, they are usually used to resize the pulling velocity or temperature gradient in directional solidification process. The structures obtained under different directional solidification conditions, and their associated properties both have been hot research points. It is difficult to observe the microstructure, which is usually on a micrometer scale, directly in experiment, and the phase-field method becomes a strong tool to understand the dendrite growth pattern. We mainly study the liquid channel formed after Fe-C alloy dendrite tip splitting under the specific condition of directional solidification and analyze the influence on liquid channel of pulling velocity in this paper. We choose the fixed thermal gradient G =20 K/mm which is on the order of the experimental value, and pulling velocity VP no more than 10 mm/s to keep the cooling rate in the range of low speed in dendrite growth, so that the interface kinetic effect can be neglected. Recent experimental results show the different interfacial energies in various compositions of Al-Zn alloy and Fe-C alloy, then we can investigate a series of directional solidification microstructures with fixed alloy Fe-0.5 wt.%C composition at different interfacial energies in our simulations. We find that the liquid channel is formed as a result of anisotropy competition between system and materials, the length and C concentration of liquid channel increase with the pulling velocity increasing, while the diameter of liquid channel is constant. It is interesting to find that there is a minimum of pulling velocity almost equal to 1 mm/s, the tip will not split and no liquid channel forms in the following steps either when the velocity is smaller than the minimum. We also compare the segregation caused by solute enrichment in liquid channel and solute segregation between dendrite arms in a series of simulations: the former is more serious than the latter. Then we point out the way to reduce the segregation caused by liquid phase channel by reducing the pulling velocity properly. It will be more practical to couple the flow field with other external field, such as magnetic field, in the simulation.
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Keywords:
- directional solidification /
- liquid channel /
- pulling velocity /
- segregation
[1] Karagadde S, Yuan L, Shevchenko N, Eckert S, Lee P D 2014 Acta Mater. 79 168
[2] Ma D X, Zhou B, Andreas B P 2011 Adv. Mater. Res. 278 428
[3] Boden S, Eckert S, Gerbeth G 2010 Mater. Lett. 64 1340
[4] Haxhimali T, Karma A, Gonzales F, Rappaz M 2006 Nat. Mater. 5 660
[5] Dantzig J A, Napoli P D, Friedli J, Rappaz M 2013 Metall. Mater. Trans. A 44 5532
[6] Friedli J, Napoli P D, Rappaz M, Dantzig J A 2012 IOP Conf. Ser. 33 012111
[7] Morteza A, Sebastian G, Nikolas P 2012 Acta Mater. 60 657
[8] Salgado-Ordorica M, Desbiolles J L, Rappaz M 2011 Acta Mater. 59 5074
[9] Melendez A J, Beckermann C 2012 J. Cryst. Growth 340 175
[10] Ohno M, Matsuura K 2010 Acta Mater. 58 5749
[11] Ohno M, Matsuura K 2009 Phys. Rev. E 79 031603
[12] Wheeler A A, Boettinger W J, Mcfadden G B 1993 Phys. Rev. E 47 1893
[13] Fehlner W R, Vosko S H 1976 Can. J. Phys. 54 2159
[14] Kurz W, Fisher D J (translated by Li J G,Hu Q D) 2010 Fundamentals of Solidification (Beijing: Higher Education Press) pp158 (in Chinese) [库兹W, 费舍D J 著 (李建国,胡侨丹 译) 2010 凝固原理 (北京: 高等教育出版社) 第158页]
[15] Wang X B, Lin X, Wang L L, Yu H L, Wang M, Huang W D 2013 Acta Phys. Sin. 62 078102 (in Chinese) [王贤斌, 林鑫, 王理林, 宇红雷, 王猛, 黄卫东 2013 物理学报 62 078102]
[16] Xie Y 2012 Ph. D. Dissertation (Leicester: University of Leicester) (in Chinese) [谢玉 2012 博士论文 (雷彻斯特市: 雷彻斯特大学)]
[17] Burden M H, Hunt J D 1974 J. Cryst. Growth 22 109
[18] Hunt J D, Lu S Z 1996 Metall. Mater. Trans. A 27 611
[19] Lu S Z, Hunt J D 1992 J. Cryst. Growth 123 17
[20] Guo C W, Li J J, Ma Y, Wang J C 2015 Acta Phys. Sin. 64 148101 (in Chinese) [郭春文, 李俊杰, 马渊, 王锦程 2015 物理学报 64 148101]
[21] Zhang Y P, Lin X, Wei L, Peng D J, Wang M, Huang W D 2013 Acta Phys. Sin. 62 178105 (in Chinese) [张云鹏, 林鑫, 魏雷, 彭东剑, 王猛, 黄卫东 2013 物理学报 62 178105]
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[1] Karagadde S, Yuan L, Shevchenko N, Eckert S, Lee P D 2014 Acta Mater. 79 168
[2] Ma D X, Zhou B, Andreas B P 2011 Adv. Mater. Res. 278 428
[3] Boden S, Eckert S, Gerbeth G 2010 Mater. Lett. 64 1340
[4] Haxhimali T, Karma A, Gonzales F, Rappaz M 2006 Nat. Mater. 5 660
[5] Dantzig J A, Napoli P D, Friedli J, Rappaz M 2013 Metall. Mater. Trans. A 44 5532
[6] Friedli J, Napoli P D, Rappaz M, Dantzig J A 2012 IOP Conf. Ser. 33 012111
[7] Morteza A, Sebastian G, Nikolas P 2012 Acta Mater. 60 657
[8] Salgado-Ordorica M, Desbiolles J L, Rappaz M 2011 Acta Mater. 59 5074
[9] Melendez A J, Beckermann C 2012 J. Cryst. Growth 340 175
[10] Ohno M, Matsuura K 2010 Acta Mater. 58 5749
[11] Ohno M, Matsuura K 2009 Phys. Rev. E 79 031603
[12] Wheeler A A, Boettinger W J, Mcfadden G B 1993 Phys. Rev. E 47 1893
[13] Fehlner W R, Vosko S H 1976 Can. J. Phys. 54 2159
[14] Kurz W, Fisher D J (translated by Li J G,Hu Q D) 2010 Fundamentals of Solidification (Beijing: Higher Education Press) pp158 (in Chinese) [库兹W, 费舍D J 著 (李建国,胡侨丹 译) 2010 凝固原理 (北京: 高等教育出版社) 第158页]
[15] Wang X B, Lin X, Wang L L, Yu H L, Wang M, Huang W D 2013 Acta Phys. Sin. 62 078102 (in Chinese) [王贤斌, 林鑫, 王理林, 宇红雷, 王猛, 黄卫东 2013 物理学报 62 078102]
[16] Xie Y 2012 Ph. D. Dissertation (Leicester: University of Leicester) (in Chinese) [谢玉 2012 博士论文 (雷彻斯特市: 雷彻斯特大学)]
[17] Burden M H, Hunt J D 1974 J. Cryst. Growth 22 109
[18] Hunt J D, Lu S Z 1996 Metall. Mater. Trans. A 27 611
[19] Lu S Z, Hunt J D 1992 J. Cryst. Growth 123 17
[20] Guo C W, Li J J, Ma Y, Wang J C 2015 Acta Phys. Sin. 64 148101 (in Chinese) [郭春文, 李俊杰, 马渊, 王锦程 2015 物理学报 64 148101]
[21] Zhang Y P, Lin X, Wei L, Peng D J, Wang M, Huang W D 2013 Acta Phys. Sin. 62 178105 (in Chinese) [张云鹏, 林鑫, 魏雷, 彭东剑, 王猛, 黄卫东 2013 物理学报 62 178105]
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