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采用单辊急冷技术实现了NiAl-Mo三元两相共晶合金的快速凝固, 同时与常规条件下的凝固组织进行了对比研究. 实验发现, 单辊急冷的合金条带与常规条件的凝固样品均由B2结构的NiAl金属间化合物和bcc结构的Mo固溶体两相组成, 两相均具有(110)晶面优先生长的趋势, 并呈现出(110)NiAl//(110)Mo取向关系. 常规条件下得到的微观结构主要由规则的两相共晶组织组成, 形成了类似菊花状的共晶胞. 而单辊急冷条件下形成的组织结构主要是由近辊面的柱状晶区和近自由面的等轴晶区组成的凝固组织. 理论计算发现, 合金熔体的单辊辊速由10 m/s增大至50 m/s后, 其冷却速率从1.01×107 K/s逐渐增大到2.46×107 K/s, 冷却速率明显高于常规铸造过程, 因而形成了差别很大的凝固组织. 随着辊速(冷却速率)的增加, 合金条带的厚度从54.4 μm减小至22 μm, 近辊面柱状晶区的厚度所占比例也逐渐增大, 晶粒发生了明显细化.The rapid solidification of ternary NiAl-Mo eutectic alloy is investigated by using melt-spinning technique, and the conventional casting is also carried out for a comparison study. The phase constitutions of the alloy samples obtained from different experiments each include both B2-NiAl intermetallic and bcc-Mo solid solution, which are both presented in the 〈110〉priority growth direction. The growth orientation relationship of the coupled two eutectic phases are obtained to be (110)NiAl//(110)Mo. The cast alloy is composed mainly of two regular eutectic phases in structure and exhibits daisy-like eutectic cells. However, the melt-spinning ribbons show the microstructures of the columnar grain near the roller surface zone and the equiaxed grain near the air zone. With the wheel speed increasing from 10 m/s to 50 m/s, the cooling rate of the alloy ribbons increases from 1.01×107 K/s to 2.46×107 K/s, while the thickness of alloy ribbons decreases from 49.4 μm to 22 μm. Meanwhile, the volume fraction of columnar grain zone increases gradually, and the grains are refined obviously. The cooling rate in the melt-spinning experiment for alloy ribbon is obviously higher than that in the conventional casting test, which leads to a significant difference in solidification microstructure between two techniques.
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Keywords:
- rapid solidification /
- ternary eutectic /
- eutectic transformation /
- cooling rate
[1] Bei H, George P G 2005 Acta Mater. 53 69
[2] Ferrandini P, Batista W W, Caram R 2004 J. Alloys Compd. 381 91
[3] Gao Q, Guo J T, Huai K W 2007 Intermetallics 15 734
[4] Tang L Z, Zhang Z G, Li S S, Gong S K 2010 Trans. Nonferrous Met. Soc. China 20 212
[5] Sun H P, Shen J, Zhang J F, Fu H Z 2010 Rare Metal Mat. Eng. 39 1009 (in Chinese) [苏慧平, 沈 军, 张建飞, 傅恒志 2010 稀有金属材料与工程 39 1009]
[6] Liang Y C, Guo J T, Zhou L Z, Zhang C L, Lin J D 2010 Mater. Lett. 64 1707
[7] Ebrahimi F, Shrivatava S 1998 Acta Mater. 46 1493
[8] Gali A, Bei H, George E P 2010 Acta Mater. 58 421
[9] Rablbauer R, Fischer R, Frommeyer G 2004 Z. Metallkd. 95 525
[10] Frommeyer G, Rablbauer R, Schafer H J 2010 Intermetallics 18 299
[11] Xie Y, Guo J T, Zhou L Z, Chen H D, Long O Y 2010 Trans. Nonferrous Met. Soc. China 20 2265
[12] Deputier S, Guerin R, Ballini Y, Guivarch A 1995 J. Alloys Compd. 217 13
[13] Zhang Q A, Zhao G P, Hou Q Y, Wu H Y 2005 Mater. Sci. Eng. A 397 113
[14] Dudova M, Kucharova K, Bartak T, Bei H, George E P, Somsen C, Dlouhy A 2011 Scripta Mater. 65 699
[15] Poirier D, Salcudean M 1988 J. Heat Transfer 110 562
[16] Xu J F, Wei B B 2004 Acta Phys. Sin. 53 1909 (in Chinese) [徐锦锋, 魏炳波 2004 物理学报 53 1909]
[17] Li Z Q, Wang W L, Zhai W, Wei B B 2011 Acta Phys. Sin. 60 108101 (in Chinese) [李志强, 王伟丽, 翟薇, 魏炳波 2011 物理学报 60 108101]
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[1] Bei H, George P G 2005 Acta Mater. 53 69
[2] Ferrandini P, Batista W W, Caram R 2004 J. Alloys Compd. 381 91
[3] Gao Q, Guo J T, Huai K W 2007 Intermetallics 15 734
[4] Tang L Z, Zhang Z G, Li S S, Gong S K 2010 Trans. Nonferrous Met. Soc. China 20 212
[5] Sun H P, Shen J, Zhang J F, Fu H Z 2010 Rare Metal Mat. Eng. 39 1009 (in Chinese) [苏慧平, 沈 军, 张建飞, 傅恒志 2010 稀有金属材料与工程 39 1009]
[6] Liang Y C, Guo J T, Zhou L Z, Zhang C L, Lin J D 2010 Mater. Lett. 64 1707
[7] Ebrahimi F, Shrivatava S 1998 Acta Mater. 46 1493
[8] Gali A, Bei H, George E P 2010 Acta Mater. 58 421
[9] Rablbauer R, Fischer R, Frommeyer G 2004 Z. Metallkd. 95 525
[10] Frommeyer G, Rablbauer R, Schafer H J 2010 Intermetallics 18 299
[11] Xie Y, Guo J T, Zhou L Z, Chen H D, Long O Y 2010 Trans. Nonferrous Met. Soc. China 20 2265
[12] Deputier S, Guerin R, Ballini Y, Guivarch A 1995 J. Alloys Compd. 217 13
[13] Zhang Q A, Zhao G P, Hou Q Y, Wu H Y 2005 Mater. Sci. Eng. A 397 113
[14] Dudova M, Kucharova K, Bartak T, Bei H, George E P, Somsen C, Dlouhy A 2011 Scripta Mater. 65 699
[15] Poirier D, Salcudean M 1988 J. Heat Transfer 110 562
[16] Xu J F, Wei B B 2004 Acta Phys. Sin. 53 1909 (in Chinese) [徐锦锋, 魏炳波 2004 物理学报 53 1909]
[17] Li Z Q, Wang W L, Zhai W, Wei B B 2011 Acta Phys. Sin. 60 108101 (in Chinese) [李志强, 王伟丽, 翟薇, 魏炳波 2011 物理学报 60 108101]
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