使用有限元耦合元胞自动机模型预测水平单向凝固实验中 Al-4.5%Cu(质量分数)合金试样的温度场和微观凝固组织。晶体形核和枝晶生长动力学模型分别采用Rappaz连续形核模型和Kurz-Giovanola-Trivedi(KGT)模型简化形式,基于纯扩散条件,采用 KGT 模型简化公式计算生长参数。结果显示:数值模拟可以较准确地预测柱状晶向等轴晶转变(CET)位置和等轴晶晶粒尺寸,但因模拟未考虑晶核的运动,激冷等轴晶区的模拟有较大偏差。模拟和实验结果都证明过热度显著影响Al-Cu合金的凝固组织,过热度低于20℃条件下可以获得全等轴晶组织,否则会出现柱状晶;过热度50℃以上的试样CET位置几乎不发生变化。
The temperature field and the grain structure of Al-4.5%Cu (mass fraction) alloy in horizontal directional solidification process were predicted using a cellular automaton (CA) coupled with finite-element (FE) model. The Rappaz model was adopted to calculate the nucleation. And the Kurz-Giovanola-Trivedi (KGT) model was used to describe the growth kinetics of dendritic tips. The growth parameters of Al-4.5%Cu alloy were calculated using simplified KGT formula, which was derived based on the pure diffusion condition. The results show that the position of the columnar to equiaxed transition (CET) and the size of equiaxed grains can be simulated reasonably. However, large deviation of the simulated result exists in the chill zone as the movement of nucleus is not considered. The simulated and experimental results prove that the superheat greatly influences the solidification microstructures of Al-Cu alloy. Full equiaxed grains can be obtained if superheat is lower than 20 ℃, otherwise columnar grains will be observed. When the superheat is above 50 ℃, the positions of CET are no longer changed.
参考文献
[1] | Li, ZJ;Zhong, HG;Sun, QZ;Xu, ZQ;Zhai, QJ .Effect of cooling rate on hot-crack susceptibility of duplex stainless steel[J].Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing,2009(1/2):191-195. |
[2] | ZHONG H;TAN Y;LI H;MAO X, ZHAI Q.The effect of high superheat on the solidification structure and carbon segregation of ferrite-based alloy[A].Olando,Florida:The Minerals,Metals & Materials Society,2012:215-221. |
[3] | 仲红刚;陈湘茹;敖鹭;李仁兴,翟启杰 .凝固组织水平生长过程的模拟方法及装置[P].中国,200910199568.X,2010-08-11. |
[4] | TASSA M;HUNT J D .The measurement of Al-Cu dendrite tip and eutectic interface temperatures and their use for predicting the extent of the eutectic range[J].Journal of Crystal Growth,1976,34(01):38-48. |
[5] | 李建国;毛协民;傅恒志;史正兴.Al-Cu 合金高梯度定向凝固过程中的形态转变[J].材料科学进展,1991(06):461-466. |
[6] | 屈敏,刘林,唐峰涛,傅恒志.试样直径对Al-Cu合金定向凝固温度梯度和一次枝晶间距的影响[J].中国有色金属学报,2008(02):282-287. |
[7] | R.H. Mathiesen;L. Arnberg;P. Bleuet .Crystal Fragmentation and Columnar-to-Equiaxed Transitions in Al-Cu Studied by Synchrotron X-Ray Video Microscopy[J].Metallurgical and Materials Transactions, A. Physical Metallurgy and Materials Science,2006(8):2515-2524. |
[8] | 严卫东,刘汉武,杨爱民,熊玉华,刘林.Al-Cu合金等轴枝晶组织形成的模拟及计算机可视化[J].铸造技术,2001(06):14-16. |
[9] | 卜晓兵,李落星,张立强,朱必武,王水平.Al-Cu合金凝固微观组织的三维模拟及优化[J].中国有色金属学报,2011(09):2195-2201. |
[10] | 孙勇,赵维民,胡爱文,刘丽丽.铸件定向凝固微观组织模拟[J].铸造技术,2005(10):949-950,953. |
[11] | MATHIESEN R H;ARNBERG L .Stray crystal formation in Al 20wt.%Cu studied by synchrotron X-ray video microscopy[J].Materials Science and Engineering A,2005,413:283-287. |
[12] | D. Ruvalcaba;R.H. Mathiesen;D.G. Eskin .In situ observations of dendritic fragmentation due to local solute-enrichment during directional solidification of an aluminum alloy[J].Acta materialia,2007(13):4287-4292. |
[13] | RAPPAZ M;GANDIN C A .Probabilistic modelling of microstructure formation in solidification processes[J].Acta Metallurgical and Materials,1993,41(02):345-360. |
[14] | LANGER J S;MüLLER-KRUMBHAAR J .Stability effects in dendritic crystal growth[J].Journal of Crystal Growth,1977,42:11-14. |
[15] | LANGER J S .Dynamics of dendritic pattern formation[J].Materials Science and Engineering A,1984,65(01):37-44. |
[16] | KURZ W;GIOVANOLA B;TRIVEDI R .Theory of microstructural development during rapid solidification[J].,1986,34(05):823-830. |
[17] | LIPTON J;KURZ W;TRIVEDI R .Rapid dendrite growth in undercooled alloys[J].ACTA METALLURGICA,1987,35(04):957-964. |
[18] | 杨世铭;陶文铨.传热学[M].北京:高等教育出版社,2006:602. |
[19] | DAVIES R H;DINSDALE A T;CHART T G;BARRY T I RAND M H .Application of MTDATA to the modeling of multicomponent equilibria[J].HIGH TEMPERATURE SCIENCE,1990,26:251-262. |
[20] | POIRIER D R;SPEISER R .Surface tension of aluminum rich Al-Cu liquid alloys[J].Metallurgical Transactions A,1991,22(13):1156-1160. |
[21] | JACKSON K A;HUNT J D;UHLMANN D R;SEWARD T P .On the original equiaxed zone in casting[J].Transactions of the Metallurgical Society of AIME,1966,236:149-158. |
[22] | H. NGUYEN-THI;G. REINHART;N. MANGELINCK-NOEL .In-Situ and Real-Time Investigation of Columnar-to-Equiaxed Transition in Metallic Alloy[J].Metallurgical and Materials Transactions, A. Physical Metallurgy and Materials Science,2007(7):1458-1464. |
[23] | 司乃潮,许能俊,司松海,李云达,史剑.温度梯度对定向凝固Al-4.5%Cu合金一次枝晶间距的影响[J].材料工程,2011(04):75-79. |
[24] | CHALMERS B .The structure of ingots[J].Journal of the Australian Institute of Metals,1963,8:255-270. |
[25] | OHNO A;MOTEGI T;SODA H .Origin of the equiaxed crystals in castings[J].ISIJ International,1971,35:18-23. |
[26] | OHNO A .Formation mechanism of the equiaxed chill zone in cast ingots[J].ISIJ International,1970,34:244-248. |
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