新型多组元CoNi基高温合金γ′相稳定性以及变形机制的研究

Co-Al-W体系中γ′相的报道开辟了Co基合金研究的新热潮。此类新型Co基合金具有与Ni基合金类似的γ+γ′两相组织、优异的高温强度、抗蠕变和耐热腐蚀等性能，因而有巨大潜力作为新型高温结构材料应用于航空航天发动机上。为了解决Co-Al-W体系γ′相稳定性低和合金密度高等缺点，通过加入大量Ni元素，并添加其它多种少量合金元素替代高密度的W元素，开发了多组元CoNi基合金。本项目以不同成分的多组元CoNi基合金为研究对象，利用同步辐射高能X射线衍射、球差校正透射电镜和原子探针表征技术，在微纳观-原子尺度下深度解析合金元素和温度对γ′相粗化动力学、γ/γ′晶格错配度、元素分配、原子占位、γ/γ′相强度和γ′相缺陷能的影响机制。通过明确合金元素对γ′相稳定性和变形机制的影响规律，指导CoNi基合金的成分设计与性能优化。研究成果将为新型多组元CoNi基合金的发展与应用提供理论依据与实验数据支撑。

The report of the γ′ phase in the Co-Al-W system have attracted significant research interest. These novel Co-base superalloys have a γ+γ′ two-phase microstructure similar to that of Ni-base superalloys, excellent high-temperature strength, creep and hot-corrosion resistance, thus they have great potential to be applied in aerospace engines as novel high-temperature structural materials. In order to increase the γ′ phase stability and reduce the mass density, multi-component CoNi-base superalloys have been developed by adding a large amount of Ni and other minor alloying elements to reduce the W fraction. This project will explore the effects of alloying elements and temperature on the γ′ phase coarsening dynamics, γ/γ′ lattice mismatch, element distribution, atomic site occupancy, γ/γ′ strength and γ′ planer defect energies in multi-component CoNi-base superalloys from micro to atomic scale, using synchrotron radiation high-energy X-ray diffraction, aberration corrected transmission electron microscopy and atom probe. Revealing the influence of alloying elements on the γ′ phase stability and deformation mechanism will benefit alloy design and property optimization of the CoNi-base superalloys. The results of this project will provide theoretical and experimental data support for developing and applying these novel multi-component CoNi-base superalloys.