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李建华,张成,冯瑞成,王军军,王茂茂,李海燕,祁永年,芮执元.基于内聚力模型的 γ-TiAl合金中 γ/γ 界面裂纹扩展的多尺度模型[J].稀有金属材料与工程(英文),2021,50(5):1617~1625.[Li Jianhua,Zhang Cheng,Feng Ruicheng,Wang Junjun,Wang Maomao,Li Haiyan,Qi Yongnian and Rui Zhiyuan.Multiscale Model for Crack Propagation of γ/γ Interface in γ-TiAl Alloy Based on Cohesive Zone Model[J].Rare Metal Materials and Engineering,2021,50(5):1617~1625.]
Multiscale Model for Crack Propagation of γ/γ Interface in γ-TiAl Alloy Based on Cohesive Zone Model
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Received:October 08, 2020  
DOI:
Key words: γ-TiAl alloy  multiscale model  Voronoi tessellation  FEM-CZM
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Li Jianhua,Zhang Cheng,Feng Ruicheng,Wang Junjun,Wang Maomao,Li Haiyan,Qi Yongnian and Rui Zhiyuan  
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Abstract:
      The multiscale model was established to predict the crack propagation behavior of γ-titanium aluminide (TiAl) alloys. The constitutive parameters of the cohesive zone model (CZM) of true twin (TT) γ/γ interface were obtained by molecular dynamics (MD). The mesoscopic model of polycrystalline γ-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 of γ-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 of γ-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-γ 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.