Fe-C合金等温凝固过程的相场法模拟
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摘要
Fe-C合金系是目前应用最为广泛的工程结构材料,其力学性能的优劣和使用寿命的长短,与合金铸件在凝固过程中所形成的微观组织有关。用相场法进行合金凝固时微观组织所形成过程的模拟,对优化工艺参数、提高铸件质量,不仅具有重要的理论学术意义,而且也具有重要的工程应用价值。
     本文采用KKS(Kim,Kim,Suzuki.)模型,基于自由能泛函数推导了纯金属、单相二元合金及多元合金的相场控制方程,并重点对Fe-0.5mol%C单相二元合金等温凝固的相场控制方程和溶质控制方程进行推导。相场模型中考虑了界面各向异性,并引入了诱发侧向分支的扰动项,也为模型确定了合适的边界条件和初始条件等,采用基于均匀网格的有限差分法对控制方程进行了离散。采用基于Visual C++6.0平台的C语言进行编程,实现了用Tecplot10.0和Origin7.0将模拟结果以及凝固特征参数可视化。
     研究了晶粒的长大过程及各向异性强度对枝晶形貌的影响。结果表明,晶体生长初期,晶粒形貌为球状,随着计算时间的推移,晶粒形貌由球状经星形向枝晶形状转变,最后形成复杂的树枝晶;在不考虑成分过冷的时候,各向异性是使晶粒形貌以枝晶方式生长的最主要原因。
     研究了过冷度、各向异性强度和扰动强度对枝晶生长形貌的影响。结果表明,随着过冷度的减小,枝晶主干细化,各向异性程度增大,晶粒生长速度减小,溶质扩散层厚度增加,枝晶的最高溶质浓度降低,溶质梯度减小;随着各向异性的增加,晶粒由海藻状转变为枝晶状,枝晶生长速度也随之增大;扰动是引发枝晶的侧向分支的主要原因。各向异性强度和扰动强度均对枝晶溶质分布的影响并不显著。
     分析了枝晶生长过程中溶质分布情况。结果表明,溶质分布情况均与实际枝晶的溶质分布情况相一致。
     为了考核模拟结果,对Fe-C合金的凝固过程进行实验研究,并对试样进行了微观组织分析。结果表明,模拟结果与实际凝固结果基本一致,验证了相场模型的正确性。
Fe-C alloy system is the most widely used material for the engineering structures at present time. The mechanical properties and durability property of the alloy lie on the solidification microstructures in the casting process. Modeling of the alloy microstructure formation using phase-field model will help to evaluate and optimize the castings processing technology so as to improve their quality.
     Adopted KKS model and based on free energy function, the phase-field model of pure metal, binary single-phase alloy and multiple components alloy are derived respectively. Emphasis on derived the equation of phase-field and solute-field of binary single-phase alloy of the Fe-0.5mol%C under isothermal condition. The interface anisotropy is taken into account and a term of noise to produce the side-branches is introduced into the phase-field model. The initial conditions and boundary conditions is determined too. In order to solve the phase-field and solute-field equations used Finite Difference Formulas on uniform mesh. The computational program is programed by using Visual C++6.0. The vision result of simulation is achieved by using Tecplot 10.0 software and the curve of solidification characteristic parameter is showed by using Origin 7.0 software.
     The grain growth process and the influence of anisotropic intensity on dendrite morphologies are investigated. The results show that during the early stages of growth, the morphology of crystal grain is spherical, with increasing of time, the grain morphologies will transform into star shape from spheric shape, and then change as complex dendrite morphologies. The grain morphologies trend to dendritic by anisotropism.
     The influences of undercooling, anisotropic intensity and noise intensity on dendrite growth are investigated. The results show that with decreasing of undercooling, the morphology of dendritic trunk will become thinner, while anisotropic degree is increased, the speed of dendrite growth is decreased, thickness of solute diffusion layer is increased. The maximum solute concentration is decreased, the solute gradient is decreased. With increasing of anisotropic intensity, the grain morphology is transformed from seaweed to dendrite, and the speed of dendrite growth is increased. The main reason of dendrite side-branches is caused by the noise intensity. The influence of anisotropic intensity and noise intensity on the solute distribution of dendrite is not significant.
     The solute distribution on dendrite growth process is also investigated. The results show that the solute distribution of simulation is same as the actual case.
     In order to confirm the result from computer simulation, the solidification process of Fe-C alloy is carried on experimentally, and the microstructure of testing sample is studied in detail. The results show that the simulation results are almost same as the experimental results, which indicates that the conclusion results from the phase-field model simulation is successful.
引文
[1]李庆春.铸件形成理论基础[M].哈尔滨:哈尔滨工业大学出版社,1980:1-149.
    [2]石德珂.材料科学基础[M].北京:机械工业出版社,1995.
    [3]罗伯D[德].计算材料学[M]项金钟,吴兴惠译.北京:化学工业出版社.2002.9.
    [4]熊玉华,刘林.铸件凝固组织形成的计算机模拟[J].材料导报,1999,13(3):20-21.
    [5]黄列群.铸件凝固数值模拟的研究现状及发展趋势[J].机电工程,1997,5:56-58.
    [6]柳百成,荆涛.铸造工程的模拟仿真与质量控制[M].北京:机械工业出版社,2001.
    [7]Odifield W A,Quantitative Approach to Casting Solidification[J].Freezing of Cast Iron,ASM Trans.1966,59(2):945-960.
    [8]Hunt J D.Steady State Columnar and Equiaxed Growth of Dendrites and Eutectic[J].Mater.Sci.Eng.,1984,65:75-83.
    [9]Thevoz Ph,Desbiolies J L,Rappaz M.Modeling of Equiaxed Microstructure Formation in Casting[J].Metall.Trans.A,1989,20:311-321.
    [10]Rappaz M.,Thevoz Ph.Solute Diffusion Model for Exquiaxed Dendritic Growth:Analytical Solidification[J].Acta Metall,1987,35(12):2929-2933.
    [11]Wang C Y.,Beckermann C.Prediction of Columnar to Equiaxed Transition during Diffusion-Controlled Dendritic Alloy Solidification[J].Metall.Trans.A,1994,25:1081-1093.
    [12]Wang C Y,Beckermann C.Equiaxed Dendritic Solidification with Convection Multiscale/Multiphase Modeling[J].Metall Mater.Trans.A,1996,27(9):2754-2764.
    [13]Wang C Y,Beckermann C.Equiaxed Dendritic Solidification with Convection Numerical Simulations for an Al-4 Wt pct Cu Alloy[J].Metall Mater.Trans.A,1996,27(9):2765-2783.
    [14]Beckermann C,Wang C Y.Equiaxed Dendritic Solidification with Convection:PartⅢ.Comparisons with NH_4Cl-H_2O Experiments[J].Metall Trans.1996,27(9):2784-2795.
    [15]Spittle J A,Brown S G R.Computer Simulation of the Effects of Alloy Variables on the Grain Structures of Castings[J].Acta Metall.,1989,37(7):1803-1810.
    [16]Spittle J A,Brown S G R.A Computer Simulation of the Influence of Processing Conditions on As-cast Grain Structures[J].J.Mater.Sci.,1989,23:1777-1781.
    [17]Zhu P,Smith R W,Dynamic Simulation of Crystal Growth by Monte Carlo Method Ⅰ.Model Description and Kinetics[J].Acta Metall.,1992,40(4):683-692.
    [18]Zhu P,Smith R W,Dynamic Simulation of Crystal Growth by Monte Carlo Method Ⅱ.Ingot Microstructures[J].Acta Metall,1992,40(12):3369-3379.
    [19]Crespo D,Pradell T.Kinetic Theory of Microstructural Evolution in Nucleation and Growth Process[J].Mater.Sci.Enging.1997,238:160-165.
    [20]Lee H N,Ryoo H S.Monte Carlo Simulation of Microstructural Evolution Based on Grain Boundary Character Distribution[J].Mater Sci.Enging.2000,281:176-188.
    [21]Liguo Wang,Paulette Clancy.Kinetic Monte Carlo Simulation of the Growth of Poly crystalline Cu Films[J].Surface Science.2001,473:25-38.
    [22]许庆彦,柳百成.铸造合金凝固组织的计算机模拟与预测[J].稀有金属材料与工程,2003,32(6):401-406.
    [23]丁雨田,王海南,许广济等.Monte Carlo方法在定向凝固模拟中的应用[J].特种铸造及有色合金,2001,(2):83-85.
    [24]王同敏.金属凝固过程微观模拟研究[D].大连理工大学博士学位论文,2000.
    [25]Brown S G R,Bruce N B.Three-dimensional Simulation Cellular Automaton Model of Microstructural Evolution during Solidification[J].Journal of Material Science,1995,30(5):1144-1150.
    [26]刘红艳,何宜柱.元胞自动机模拟及其在金属材料设计中的应用[J].安徽工业大学学报,2001,18(4):290-294.
    [27]Brown S G R.A Three-dimensional Cellular Automaton Model of 'free' Dendritic Growth [J].Scripta Metallurgica et Materialia,1995,32(2):241-246.
    [28]Zhu M F,Hong C P.A three Dimensional Modified Cellular Automation Model for the Prediction of Solidification Microstructures[J].ISIJ International,2002,42(5):520-526.
    [29]Brown S G R.Simulation of Diffusional Composite Growth Using the Cellular Automaton Finite Difference(CAFD) Method[J].Journal of Materials Science,1998,33(19):4769-4773.
    [30]Jarvis D J,Brown S G R,Spittle J A.Modeling of Non-equilibrium Solidification in Ternary Alloys:Comparison of 1D,2D,and 3D Cellular Automaton-finite Difference Simulations[J].Materials Science and Technology,2000,16:1420-1424.
    [31]Rappaz M,Candin Ch A.Probabilistic Modeling of Microstructure Formation in Solidification Process[J].Acta Metall.,1993,41(2):345-360.
    [32]Rappaz M,Charbon Ch A,Sasikumar R.Probabilistic Modeling of Microstructure Formation in Solidification Process[J].Acta Metall.,1994,42:2365-2374.
    [33]Rappaz M,Gandin C A,Tintiller R.Three-Dimensional Simulation of the Grain Formation in Investment Casting[J].Metallurgical Trans.,1994,25(3):629-635.
    [34]Gandin Ch A,Rappaz M.A Coupled Finite Element-Cellular Automation Model for the Prediction of Dendritic Grain Structures in Solidification Process[J].Acta Metall.,1994,42(7):2223-2246.
    [35]Gandin Ch A.,Pappaz M.,Trivedi R.Three Dimensional Simulation of the Grain Formation in Investment Casting[J].MetaIl.Mater.Trans.A,1994,25(2):629-637.
    [36]Rappaz M,Gandin C A,Thevoz Ph,et al.Predication of Grain Structure in Various Solidification Process[J].MetaIl.Mater.Trans.A,1996,27(3):695-750.
    [37]Gandin Ch A,Rappaz M.Trivedi R.Three Dimensional Probabilistic Simulation of Solidification Grain Structures[J].Metall.Mater.Trans.A,1993,24:467-479.
    [38]Gandin Ch A,Desbiolies J L,Rappaz M,et al.Grain Texture Evaluation during Columnar Growth of Dendritic Alloys[J].Metall.Mater.Trans.A,1999,30(12):3153-3162.
    [39]Lee K Y,Hong C P.Stochastic Modeling of Solidification Grain Structure of Al-Cu Crystal Line Ribbons in Planar Casting[J].ISIJ Int.,1997,37(1):38-46.
    [40]Cho I S,Hong C P.Modeling of Microstructural Evolution in Squeeze Casting of an Al-4.5mass%Cu Alloy[J].ISIJInt.,1997,37(11):1098-1106.
    [41]Lee S Y,Lee S M,Hong C P.Numerical Modeling of Deflected Columnar Dendritic Grains Solidified in a Flowing Melt and Its Experimental Verification[J].ISIJ Int.,2000,40(1):48-57.
    [42]Thomas B G.,Beckermann C.Proceedings of Modeling Casting and Welding and Advanced Solidification Processes V_Ⅲ[C].USA:1998,17-132(included 3 papers).
    [43]Cho S H.Contribution of Nucleation Process to Grain Formation in Calculating Solidification Microstructure by CA-DFD[R].Tokyo.Japan.2000.
    [44]Zhu M F,Hong C P.A Modified Cellular Automaton Model for the Simulation of Dendritic Growth in Solidification of Alloys[J].ISIJ Int.,2001,41(5):436-445.
    [45]Zhu M F,Kim J M,Hong C P.Modeling of Globular and Dendritic Structure Evolution in Solidification of an Al-7mass%Si Alloy[J].ISIJ Int.,2001,41(9):992-998.
    [46]Chang S R,Kim J M,Hong C P.Numerical Simulation of Microstructure Evolution of Al Alloys in Centrifugal Castin[J].ISIJ Int.,2001,41(7):738-747.
    [47]Geiger J,Roosz A.Simulation of Grain Coarsening in Two Dimensions by Cellular-automaton[J].Acta Materialia,2001,49(4):623-629.
    [48]李殿中,苏仕方.镍基合金叶片凝固过程铸件微观组织模拟及工艺优化研究[J].铸造,1997,(8):1-7.
    [49]李殿中,杜强,胡志勇.金属成形过程中组织演变的Cellular Automaton模拟技术[J].金属学报,1999,32(1):1201-1205.
    [50]Beckermarm C,Diepers H J,Steinbach I,et al.Modeling Melt Convection in Phase-Field Simulation of Solidification[J].Comput Phys.,1999,154(1):456-496.
    [51]Beckermann C,Viskanta R.Mathematical Modeling of Transport Phenomena During Solidification of Alloys[J].Appl Mech Rev.,1993,46(1):1-7.
    [52]于艳梅,吕衣礼,张振忠.相场法凝固组织模拟的研究进展[J].铸造,2000,49(9):507-511.
    [53]Collins J B,Levin H.Diffuse Interface Model of Diffusion-Lim-ited Crystal Growth[J].Physical Review B,1985,31(9):6119-6122.
    [54]Caginalp G,Fife P C.Dynamics of Layered Interfaces Arising From Phase Boundaries[J].SIAM Journal of Apply Mathematics.,1988,48(3):506-510.
    [55]Caginalp G.Stefan and Hele-Shaw Type Model as Asymptotic Limits of the Phase-field Equations[J].Physical ReviewA,1989,39(11):5887-5890.
    [56]Fife P C,Gill G S.Phase Transition Mechanism Ms for the Phase-field Model under Internal Heating[J].Physical ReviewA,1991,43(2):843-851.
    [57]Kobayashi R.Modeling and Numerical Simulations of Dendritic Crystal Growth[J].Physical Review D.,1993,63(10):410-423.
    [58]Murrary B T,Wheeler A A,Glicksman M E.Simulation of Experimentally Observed Dendritic Growth Behavior Using a Phase-field Model[J].Crystal Growth.1995,154:44-62.
    [59]Wang S L,Sekerka R F,Wheeler A A,et al.Thermodynamically Consistent Phase-field Models for Solidification[J].Physica D.1993,69:189-200.
    [60]Karma A,Rappel W J.Phase-field Method for Computationally Efficient Modeling of Solidification with Arbitrary Interface Kinetics[J].Physical Review E.,1996,53(4):3017-3020.
    [61]Karma A,Rappel W J.Numerical Simulation of Three-dimensional Dendritic Growth[J].Physical Review Letter,1996,7(10):4050-4053.
    [62]Tonhardt R,Amberg G.Phase Field Simulation of Dendritic Growth in a Shear flow[J].Journal of Crystal Growth,1998,194(7):406-425.
    [63]Kim S G,Kim W T,Suzuki T.Interfacial Compositions of Solid and Liquid in a Phase-field Model with Finite Interface Thickness for Isothermal Solidification in Binary Alloys[J].Physica Review E.,1998,58(3):3316-3323.
    [64]Lee J S,Suzuki T.Numerical Simulation of Isothermal Dendritic Growth by Phase-field Model[J].ISIJ Int.,1999,39(3):246-252.
    [65]Kim S G,Kim W T,Lee J S,et al.Large Scale Simulation of Dendritic Growth in Pure Undercooled Melt by Phase-field Model[J].ISIJ Int.,1999,39(4):335-340.
    [66]Tong X,Beckermann C.Velocity and Shape Selection of Dendritic Crystals in a Forced Flow[J].Physical Review E.,2000,61(1):49-52.
    [67]Zhu M F,Kim J M,Hong C P.Numerical Prediction of the Secondary Dendrite Arm Spacing Using a Phase-field Model[J].ISIJ Int.,2001,41(4):345-349.
    [68]许庆彦,柳百成.采用Cellular Automaton法模拟铝合金的微观组织[J].中国机械工程,2001,12(3):328-331.
    [69]金俊泽,王宗廷,郑贤淑,等.金属凝固组织形成的仿真研究[J].金属学报,1998,34(9):928-932.
    [70]唐勇,金俊泽.金属凝固组织的计算机仿真[J].大连理工大学学报,1997,37(5):560-563.
    [71]龙文元.铝合金凝固过程枝晶生长的相场法数值模拟[D].华中科技大学博士学位论文,2004.
    [72]龙文元,蔡启舟,巍伯康.二元合金非等温凝固过程的相场法模拟[J].铸造,2003,52(9):695-699.
    [73]龙文元,蔡启舟,陈立亮.二元合金等温凝固过程的相场模拟[J].物理学报,2005,54(01):0256-0261.
    [74]刘小刚.Al-Cu合金等温凝固的相场法模拟[D].沈阳工业学院硕士学位论文,2003.
    [75]于艳梅.过冷熔体中枝晶生长的相场法数值模拟[D].西北工业大学博士学位论文,2002.
    [76]刘静.金属凝固过程微观组织形成的相场法模拟研究[D].西北工业大学硕士学位论文,2006.
    [77]王帆.基于KKS模型Al-Cu合金等温凝固过程相场法模拟[D].兰州理工大学硕士学位论文,2006.
    [78]胡卫英.金属过冷熔体中枝晶侧枝生长的相场法模拟[D].西北工业大学硕士学位论文,2007.
    [79]田卫星.纯金属凝固过程枝晶生长的相场法研究[D].山东大学博士学位论文,2007.
    [80]Caginalp G,Xie W.Phase-field and Sharp-interface Alloy Models[J].Phys.Rev.E.1993,48(3):1897-1909.
    [81]Wheeler A A,Murrary B T,Schaefer R J.Computation of Dendrites Using a Phase Field Model[J].Physical D,1993,66(10):243-262.
    [82]Kim Y T,Provatas N.Goldenfeld N.Dantzig J.Universal Dynamics of Phase-field Models for Dendritic Growth[J].Physical Review E,1999,59(9):2546-2549.
    [83]Steinbach I,Pezzolla F,Nestler B,at el.A Phase Field Concept for Multiphase Systems[J].Physica D,1996,94:135-147.
    [84]Kim S G,Kim W T,Suzuki T.Phase-field Model for Binary Alloys[J].Physical Review E.1999,60(6):7186-7197.
    [85]Kim S G,Kim W T,Suzuki T.Interfacial Compositions of Solid and Liquid in a Phase-field Model with Finite Interface Thickness for Isothermal Solidification in Binary Alloys[J].Physical Review E.,1998,58(3):3316-3323.
    [86]Ode M.Lee J S,Kim W T,et al.Phase-field Model for Solidification of Ternary Alloys[J].ISIJ International,2000,40(9):870-876.
    [87]Kim W T,Kim S G,Lee J S.Equilibrium at Stationary Solid-Liquid Interface during Phase-Field Modeling of Alloy Solidification[J].Metallurgical And Materials TransactionsA.2001,32(4):961-969.
    [88]Toshio S,Machiko O,Kim S G.,et al.Phase-field Model of Dendritic Growth[J].Journal of Crystal Growth.,2002,237(3):125-131.
    [89]M.Ode,T.Suzuki,S.G.Kim,et al.Phase-field Modle for Solidification of Fe-C alloys[J].Science and Technology of Advanced Materials.2000,(1):43-49.
    [90]M.Ode,T.Suzuki.Numerical Simulation of Initial Microstructure Evolution of Fe-C Alloys Using a Phase-field Model[J].ISIJ Int.,Vol.2002,42(4):368-374.
    [91]胡汉起.金属凝固原理[M].北京:机械工业出版社,2000.
    [92]荆涛.凝固过程数值模拟[M].北京:电子工业出版社,2002.
    [93]Kessler D A,Levine H.Velocity Selection in Dendritic Growth[J].Phys.Rev.B.,1986,33(11):7867-7870.
    [94]谢锐生.热力学原理[M].北京:人民教育出版社,1980.

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