复杂受限空间中强制对流条件下镍基高温合金凝固组织演变机制

先进航空发动机的轻量化带动了高温合金复杂薄壁铸件的巨大需求。液态金属在铸型中的流动是复杂薄壁铸件凝固过程和枝晶生长过程中的重要传输现象，也是制约铸件完整成型和微观组织形成的主要因素。本项目针对复杂受限空间K4169高温合金薄壁铸件在强制对流作用下的凝固组织演变机制开展数值模拟和实验研究。基于格子玻尔兹曼（LBM）对流传热传质模型，以Ni-Cr-Fe-Nb四元合金为模型合金，发展一种耦合热力学计算和组织模拟技术的多尺度计算方法，提供一套包含熔体流动、传热传质和液固相变等复杂物理过程的定量数值模型。基于强制对流下K4169高温合金复杂薄壁铸件枝晶演变规律和凝固组织特点，揭示熔体流动行为及凝固组织演变机制，为高性能复杂薄壁高温合金铸件精密成型提供理论依据。

The lightweight of advanced aircraft engine drove the huge demand of complex thin-walled superalloy castings. For complex thin-walled castings, liquid metal flow in the mold is an important transmission phenomenon both in the solidification process and in dendritic growth process, and, is also the main factors in restricting complete deforming and microstructure evolution of castings. This project is aimed at numerical simulation and experimental research of the evolvement mechanism of solidified microstructure in complex constrained space with forced convection of K4169 superalloy thin-walled castings. Based on Lattice Boltzmann Method (LBM) convection heat and mass transfer model and Ni-Cr-Fe-Nb quaternary alloy, development a multi-scale calculation method coupled thermodynamic calculation and simulation technology, provides a set of quantitative numerical model contains complex physical processes such as melt flow, heat and mass transfer and liquid-solid phase transformation. Based on the dendrite evolution law and the characteristics of the solidified microstructure of K4169 superalloy complex thin-walled castings with force convection, explain the physics phenomenon obtained by anti-gravity casting and synchrotron radiation experimental, reveal the melt flow behavior and solidification microstructure evolution mechanism, to provide theory basis of high performance complex thin-walled superalloy casting precision forming.