气动悬浮冷速控制及Al－7.7Ca共晶合金的凝固组织

张龙; 张曙光; 余建定; 李建国

doi:10.3724/SP.J.1037.2012.00718

金属学报 >

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

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

论文

气动悬浮冷速控制及Al－7.7Ca共晶合金的凝固组织

张龙 ,
张曙光 ,
余建定 ,
李建国

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1) 上海交通大学材料科学与工程学院, 上海 200240
2) 中国科学院上海硅酸盐研究所, 上海 200050

张龙, 男, 1989年生, 硕士生

收稿日期: 2012-12-06

修回日期: 2013-01-11

网络出版日期: 2013-04-11

基金资助

国家自然科学基金项目51027005和上海市科委资助项目11JC1405900资助

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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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摘要

分析了气动悬浮金属样品在凝固过程中的激光能量吸收、热辐射以及对流换热特性, 推导出激光功率调控下的冷速控制公式. 根据气动悬浮Al－7.7Ca共晶合金样品的温度－时间曲线, 验证了计算与实测结果符合较好. 金相观察表明, 气动悬浮Al－7.7Ca共晶合金在低冷速下凝固时呈现规则层片共晶形态;随着冷速提高, 过冷度增大, 晶粒细化, 层片间距减小, 不规则粒状共晶的体积分数不断增加, 证实不规则共晶形成于凝固初期的快速凝固阶段. 规则共晶的层片间距与过冷度的关系符合经典的JH理论, 说明其形成于再辉后的慢速凝固阶段.

关键词： 铝合金; 气动悬浮; 冷却速率; 凝固; 组织

本文引用格式

张龙 , 张曙光 , 余建定 , 李建国 . 气动悬浮冷速控制及Al－7.7Ca共晶合金的凝固组织[J]. 金属学报, 2013 , 29(4) : 451 -456 . DOI: 10.3724/SP.J.1037.2012.00718

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

参考文献

[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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