基于内聚力模型的γ-Ti Al合金中γ/γ界面裂纹扩展的多尺度模型  

Multiscale Model for Crack Propagation of γ/γ Interface inγ-TiAl Alloy Based on Cohesive Zone Model

作　　者：李建华[1,2] 张成 冯瑞成[1,2] 王军军 王茂茂 李海燕[1,2] 祁永年 芮执元[1,2] Li Jianhua;Zhang Cheng;Feng Ruicheng;Wang Junjun;Wang Maomao;Li Hai-yan;Qi Yongnian;Rui Zhiyuan(School of Mechanical and Electrical Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Key Laboratory of Digital Manufacturing Technology and Application,Ministry of Education,Lanzhou University of Technology,Lanzhou 730050,China;LS Casting and Forging Branch,Lanzhou LS Group Co.,Ltd,Lanzhou 730050,China)

机构地区：[1]兰州理工大学机电工程学院,甘肃兰州730050 [2]兰州理工大学数字制造技术与应用省部共建教育部重点实验室,甘肃兰州730050 [3]兰州兰石集团有限公司兰石铸锻分公司,甘肃兰州730050

出　　处：《稀有金属材料与工程》2021年第5期1617-1625,共9页Rare Metal Materials and Engineering

基　　金：National Natural Science Foundation of China(52065036,51865027);Hongliu First-class Disciplines Development Program of Lanzhou University of Technology。

摘　　要：通过建立多尺度模型预测γ-TiAl合金中裂纹的扩展行为。利用分子动力学(MD)建立了真孪晶(TT)γ/γ界面模型,得到了界面内聚力区域(CZM)的本构参数;采用Voronoi方法生成了多晶γ-Ti Al合金介观模型,将CZM本构参数耦合到该模型中,得到了对应的不含缺陷、含钝裂纹和钝裂纹+中心空洞缺陷的临界应力断裂云图,利用几何相似性平均了多晶模型和整体裂纹拉伸关系曲线并分析了γ-Ti Al合金的损伤机理;根据连续介质假说建立了宏观有限元模型(FEM),通过对紧凑拉伸试样模拟给出了力-位移曲线并得到了材料的断裂韧性。最后,将宏观有限元模拟得到的裂纹扩展行为与实验结果进行比较,验证了该模型的有效性。结果表明:在晶粒数比例相同的情况下,缺陷对整个近γ结构的强度有着显著的敏感性,同时该多尺度方法可以有效地连接不同尺度并预测裂纹的扩展。The multiscale model was established to predict the crack propagation behavior of y-titanium aluminide(TiAl)alloys.The constitutive parameters of the cohesive zone model(CZM)of true twin(TT)γ/γinterface were obtained by molecular dynamics(MD).The mesoscopic model of polycrystalline y-TiAl was generated via Voronoi method,and the CZM constitutive parameters were coupled into the model.The corresponding critical stress fracture diagrams with non-defect,blunt crack and blunt crack+central cavity defect were obtained.Furthermore,the polycrystalline model and the overall force-displacement curve were averaged by the geometric similarity,and the damage mechanism ofγ-TiAl alloy was analyzed.At the same time,the macroscopic finite element model(FEM)was constructed according to the homogeneous material hypothesis.A cohesive region was built in the interested crack area,and then the force-displacement relationship and fracture toughness ofγ-TiAl alloy was obtained through the FEM simulation of the compact tensile specimen.Finally,the results show that the comparison between the crack propagation behavior obtained from the macroscale finite element simulation and the experimental results proves the validity of the multiscale model.The defects have a significant sensitivity on the strength of the entire near-y structure when the ratio of grain is the same,and meanwhile this analysis method can effectively connect various scales and predict the growth of cracks.

关 键 词：Γ-TIAL合金 多尺度模型 Voronoi镶嵌 有限元模型-内聚力 

分 类 号：TG146.21[一般工业技术—材料科学与工程]