Gamma-prime筏化与单晶高温合金性能退化的内在关联

Gamma-prime筏化是导致单晶合金性能退化的主要原因之一。为深入理解Gamma-prime筏化与合金性能退化的内在关联，本项目拟借助TEM技术，基于原位拉伸过程中Gamma-prime形筏、界面位错组态演变过程原位分析，探究Gamma-prime筏化过程中位错交互作用、位错与界面交互作用及界面结构演化对合金力学性能的影响；结合相场模拟，通过蠕变试验前后元素在Gamma/Gamma-prime界面占位、分布及界面结构的对比研究，探明晶格错配度、晶体取向和应力场对Gamma-prime筏化行为的影响，并提出Gamma-prime形筏的位错判断准则；在此基础上，通过Gamma-prime筏化过程的组织模拟，明确单晶合金服役过程中位错运动与原子定向扩散导致的Gamma-prime形筏与合金力学性能退化的内在关联，为新一代单晶合金微结构设计提供理论依据。

Gamma-prime rafting is one of the main reasons that lead to degradation of the properties of Ni-based single crystal superalloys. To have an in-depth understanding of the intrinsic correlation between gamma-prime rafting and degradation of mechanical properties, the influence of dislocation interactions during gamma-prime rafting, interaction between dislocation and gamma/gamma-prime interface and the structural evolution of gamma/gamma-prime interface on mechanical properties of superalloys were investigated according to in-situ analysis of gamma-prime rafting during tensile test and the evolution of dislocation configurations of gamma/gamma-prime interface by means of in-situ TEM. Combined with phase-field simulation, the comparative study of site preference and distribution of the main strengthening elements in the gamma/gamma-prime interface and interfacial structure before and after tensile test was done in order to explore the effect of lattice mismatch, the crystal orientation and stress field on gamma-prime rafting and clarify the microscopic mechanism of gamma-prime rafting. On these bases, the intrinsic correlation between degradation of mechanical properties of superalloys and gamma-prime rafting resulted from dislocation motion and atomic directed diffusion was revealed through the microstructural simulation of gamma-prime rafting during creep, offering a theoretical basis for the microstructural design of new generation single crystal superalloys.