COOLING RATE CONTROL AND SOLIDIFIED MICROSTRUCTURE OF Al－7.7Ca EUTECTIC ALLOY DURING AERODYNAMIC LEVITATION

ZHANG Long; ZHANG Shuguang; YU Jianding; LI Jianguo

doi:10.3724/SP.J.1037.2012.00718

Acta Metall Sin >

2013 , Vol. 29 >Issue 4: 451 - 456

DOI: https://doi.org/10.3724/SP.J.1037.2012.00718

COOLING RATE CONTROL AND SOLIDIFIED MICROSTRUCTURE OF Al－7.7Ca EUTECTIC ALLOY DURING AERODYNAMIC LEVITATION

ZHANG Long ,
ZHANG Shuguang ,
YU Jianding ,
LI Jianguo

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1) School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240
2) Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050

Received date: 2012-12-06

Revised date: 2013-01-11

Online published: 2013-04-11

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Abstract

The aerodynamic levitation process, which possesses the advantages of containerless solidification, easy control and versatility to materials, is a kind of advanced materials processing technology. How to accurately control the cooling rate during aerodynamic levitation is quite important for studying the processing－structure－property relationship of metallic materials. In this study, the characteristics of laser absorption, thermal radiation and heat convection of an aerodynamically levitated sample were analyzed, and a formula for the control of the cooling rate by means of tuning the laser power has been derived, which is described by:ΔT/Δt=-3[σε(T_s⁴-T_f⁴)+h(T_s-T₀)]/cρr+α(6L_s-3kΔt)/8cρπr³. By recording temperature－time curves with cooling rates of 9, 49, 98 and 253 ℃/s for the aerodynamically levitated Al－7.7Ca (mass fraction, %) eutectic alloy, the calculated values of cooling rates agree very well with the experimental data, verifying and validating the formula. Also, the microstructure of the aerodynamically levitated Al－7.7Ca eutectic alloy under different cooling rates was examined using OM and SEM. The metallographic observation shows that, under a low cooling rate of 9℃/s, the solidification structure of Al－7.7Ca alloy during aerodynamic levitation exhibits lamellar regular eutectic. With increasing the cooling rate, the undercooling measured from the recorded temperature－time curves increases, resulting in the refinement of the grain size and interlamellar spacing of regular eutectic. Moreover, there appears granular anomalous eutectic under higher cooling rates of 49, 98 and 253 ℃/s. The volume fraction of anomalous eutectic is increased with increasing the cooling rate. The anomalous eutectic is attributed to the formation during the rapid solidification stage. By measuring the interlamellar spacing of regular eutectic from Al－7.7Ca metallographs, the fitting data of interlamellar spacing and undercooling are in accordance with the classical JH model, showing that the regular eutectic is formed during slow solidification stage after recalescence.

Key words： aluminum alloy; aerodynamic levitation; cooling rate; solidification,; microstructure

Cite this article

ZHANG Long , ZHANG Shuguang , YU Jianding , LI Jianguo . COOLING RATE CONTROL AND SOLIDIFIED MICROSTRUCTURE OF Al－7.7Ca EUTECTIC ALLOY DURING AERODYNAMIC LEVITATION[J]. Acta Metall Sin, 2013 , 29(4) : 451 -456 . DOI: 10.3724/SP.J.1037.2012.00718

References

[1] Yu J D, Ishikawa T, Paradis P. J Crystal Growth, 2006; 292: 480

[2] Bertero G A, Hofmeister W H, Robinson M B, Bayuzick R J. Metall Trans, 1991; 22A: 2713

[3] Deng K, Ren Z M, Chen J Q, Jiang G C. Acta Metall Sin, 1999; 35: 739

(邓康, 任忠鸣, 陈坚强, 蒋国昌. 金属学报, 1999; 35: 739)

[4] Oran W A, Berge L H, Parker H W. Rev Sci Instrum, 1980; 51: 625

[5] Daniele F, Nada B, Majid N, Dimos P. J Appl Phys, 2011; 109: 093503

[6] Chen L, Luo X H. Acta Metall Sin, 2007; 43: 769

(陈亮, 罗兴宏. 金属学报, 2007; 43: 769)

[7] Ren L N, Cai E, Feng S. Acta Metall Sin, 2008; 44: 307

(任利娜, 蔡鳄, 冯生. 金属学报, 2008; 44: 307)

[8] Hu L, Lu X Y, Hou Z M. Physics, 2007; 36: 944

(胡亮, 鲁晓宇, 侯智敏. 物理, 2007; 36: 944)

[9] Wall J J, Weber R, Kim J, Liaw P K, Choo H. Mater Sci Eng, 2007; A445－446: 219

[10] Yasutomo A, Paul F P, Tomotsugu A, Takehiko I, Shinichi Y. Rev Sci Instrum, 2003; 74: 1057

[11] Taniguchi H, Yu J D, Arai Y, Yagi T, Fu D, Itoh M. Ferroelectrics, 2007; 346: 156

[12] Arai Y, Aoyama T, Yoda S. Rev Sci Instrum, 2004; 75: 2262

[13] Lee K J, Lee C H, Lee G W, Hwang W S, Lee C H, Yoda S, Cho W S. Thermochim Acta, 2012; 542: 37

[14] Sakai I, Murai K, Jiang L, Umesaki N, Honma T, Kitano A. J Electron Spectrosc Relat Phenom, 2005; 144－147: 1011

[15] Jia L M, Xu D M, Guo J J, Bai S H, Wang H H. Chin J Nonferrous Met, 2010; 20: 667

(贾丽敏, 徐达鸣, 郭景杰, 白世鸿, 王红红. 中国有色金属学报, 2010; 20: 667

[16] Massalski T B, Subramanian P R, Okamoto H, Kacprzak L. Binary Alloy Phase Diagrams. Materials Park, OH: ASM International, 1990: 1

[17] Yang C L, Yang G C, Lu Y P, Chen J Q, Zhou Y H. Acta Metall Sin, 2005; 41: 1053

(杨长林, 杨根仓, 卢一平, 陈甲琪, 周尧和. 金属学报, 2005; 41: 1053)

[18] Li J F, Yang G C, Zhou Y H. Acta Metall Sin, 1998; 34: 113

(李金富, 杨根仓, 周尧和. 金属学报, 1998; 34: 113)

[19] Wang Y G, Kuang H, Huang Q. Chin J Univ Metrology, 2012; 23: 139

(王玉刚, 匡环, 黄其. 中国计量学院学报, 2012; 23: 139)

[20] Huang Y L, Yang F H, Liang G Y, Su J Y. Chin J Lasers, 2003; 30: 449

(黄延禄, 杨福华, 梁工英, 苏俊义. 中国激光, 2003; 30: 449)

[21] Wang N, Cao C D, Wei B B. Acta Metall Sin, 1998; 34: 824

(王楠, 曹崇德, 魏炳波. 金属学报, 1998; 34: 824)

[22] Pu J, Wang J F, Xiao J Z, Gan Z H, Yi H Y. Chin J Nonferrous Met, 2003; 13: 835

(蒲健, 王敬丰, 肖建中, 甘章华, 易回阳. 中国有色金属学报, 2003; 13: 835)

[23] Wei B, Herlach D M, Feuerbacher B, Sommer F. Acta Metall Mater, 1993; 41: 1801

[24] Xu Z, Yao S S. Theories of Material Processing. Beijing: Science Press, 2003: 78

(徐洲, 姚寿山. 材料加工原理. 北京: 科学出版社, 2003: 78)

[25] Jackson K A, Hunt J D. Trans Met Soc AIME, 1966; 236: 1129

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