广西富有稀土Sc和热处理工艺调控Al-Cu-Mg航空铝合金性能的球差校正原位透射电镜研究

提高韧性，耐热性和抗腐蚀性并兼顾其强度是Al-Cu-Mg合金面临的重要科学问题。稀土元素Sc的添加和热处理工艺强烈地影响析出相等微观结构及性能。前期工作已制备出析出相可控含Sc的Al-Cu-Mg合金，但性能调控规律及原子作用机制尚不清楚。本项目拟在现有基础上，利用先进的球差校正透射电子显微术，包括原位成像、环形暗场成像和电子能量损失谱等，研究几种典型Cu/Mg比含Sc铝合金时效析出演变规律，阐明Sc与析出相、位错、晶界、溶质等晶体缺陷的交互作用规律，结合理论计算和性能测试，探讨Sc和热处理对提高强韧性和耐热耐蚀性的机制，建立Sc和热处理工艺与析出相、晶粒、晶界、位错等微结构参数、高低温拉伸及晶间腐蚀等性能指标之间的定量关系。研究结果将揭示Sc和热处理工艺调控Al-Cu-Mg合金强韧化和耐热耐蚀性的规律及原子作用机制等关键科学问题，为我国航空航天用高性能铝合金的制备提供理论和实验基础。

Increasing toughness, heat and corrosion resistance while maintaining strength is an important scientific question confronted with Al-Cu-Mg alloys. Both the addition of rare earth elements Sc and the heat treatment will have an important effect on the microstructure (such as nanoprecipitates) of the alloy and its associated properties. In our previous works, Sc-containing Al-Cu-Mg alloys with controllable type of precipitates have been successfully fabricated by the optimization of heat treatment. However, the modulation rules of properties and related atomic mechanism in these alloys are not clear. In this project, the advanced aberration-corrected transmission electron microscopy, including in-situ heating, annular dark-field imaging in scanning transmission electron microscope (ADF-STEM) and electron energy loss spectroscopy (EELS) etc., will be used to investigate the evolution of precipitates during aging of alloys. The interactions of Sc with precipitates, dislocation, grain boundary and solute atoms et al. will be systematically clarified. Combined with theoretic calculation and property test, the contributions of the Sc and heat treatment on the improvement of strength, toughness, heat and corrosion resistance will be explored. The relationship among the Sc addition, heat treatment, microstructure such as ageing precipitation, grain refinement, dislocation etc., as well as tensile and corrosion properties will be quantitatively analyzed. The integrated toughening, strengthening, heat- and corrosion-resistant mechanisms in the Al-Cu-Mg-Sc alloys will be finally revealed. The results from the project would provide theoretical and experimental guidance for the produce of high-performance Al alloys.