镍基单晶合金界面位错及位错网的演化对蠕变性能的影响

Ni-based single crystal superalloys are widely used as advanced aircraft turbine blade materials for their excellent creep resistance behavior.The structures of γ/γ'interface dislocations and dislocation netwoks as well as γ'directional coarsening have a close relationship with the creep mechanical properties of alloys at high temperature. We adopt a multi-scale approach from the micro to macro for studying the evolutions of interface dislocations & dislocation networks and their influences on the creep mechanical behavior in this project. The main contents include: (1) To explore the features and evolutions of interface dislocation & dislocation networks in the typical microstructure of Ni-based superalloys under different conditions (loads, temperatures and orientations) by molecular dynamics simulation, and to construct the essential relationship between the evolution of dislocation networks and γ'directional coarsening; (2) To analyze the change of the internal stress field when the evolutions of dislocations and dislocation networks, and to construct an atomistically informed flow rule;(3) To develop a creep constitutive model with consideration of the evolutions of interface dislocations & dislocation networks based on molecular dynamics simulation and crystal plasticity, and to investigate the influences of dislocation networks and their related directional coarsening on creep behavior of Ni-based single crystal superalloys. The objective of this project is to build the essential relationship between the evolution of dislocation networks and γ'directional coarsening,to further develop and improve the multi-scale approach for creep behavior, and to reveal the influences of interface dislocations & dislocation networks and their evolutions on the creep mechanical properties.

镍基单晶高温合金因具有优异的蠕变抗力性能而被广泛应用于航空发动机的涡轮叶片材料，其γ/γ'界面位错组态、位错网结构及γ'定向粗化与合金的高温蠕变力学性能密切相关。本项目采用从微观到宏观的多尺度方法探讨界面位错及位错网的演化对合金蠕变力学性能的影响。主要内容包括：（1）分子动力学模拟不同载荷、温度和取向条件下界面位错及位错网的演化特征，建立界面位错网演化同γ'定向粗化之间的联系；（2）探讨界面位错及位错网演化时原子内部应力场的变化，建立包含原子微结构演化信息的流动准则；（3）基于以上分子动力学模拟，结合晶体塑性理论，发展耦合界面位错及位错网演化的蠕变本构模型，探讨位错网演化及与之相联系的定向粗化行为对蠕变性能的影响。本项目的研究重点在于建立界面位错及位错网演化同γ'定向粗化之间的内在联系，进一步发展和完善蠕变分析的多尺度模型，探明界面位错和位错网及相关的演化行为对蠕变力学性能的影响。

镍基单晶高温合金因具有优异的蠕变抗力性能而被广泛应用于航空发动机的涡轮叶片材料，其γ/γ'界面位错组态、位错网结构及γ'定向粗化与合金的高温蠕变力学性能密切相关。本项目采用从微观到宏观的多尺度方法研究了界面位错及位错网的演化对合金蠕变力学性能的影响。主要研究内容包括：（1）采用分子动力学模拟了不同载荷、温度和取向条件下界面位错及位错网的演化特征，建立了界面位错网演化同γ'定向粗化之间的联系；（2）探讨了界面位错及位错网演化时原子内部应力场的变化，建立了包含原子微结构演化信息的流动准则；（3）在原子微结构演化信息的基础上结合晶体塑性理论，发展考虑界面位错及位错网演化的蠕变本构模型，探讨位错网演化及与之相联系的定向粗化行为对蠕变性能的影响。基于以上研究，给出了界面位错运动和位错网演化的交互作用，建立了界面位错运动、位错网损伤演化与合金力学性能的关联，揭示了镍基单晶高温合金的主要失效机理及微观本质，发展了镍基单晶高温合金定向粗化的理论预测模型。本项目的研究从原子尺度揭示了蠕变过程γ'定向粗化的微观机制及控制合金蠕变失效的主要因素，探明了界面位错和位错网及相关的演化行为对蠕变力学性能的影响，对于镍基单晶高温合金的开发和应用具有重要的理论和实际应用意义。