Al-Cu-Mg合金中典型纳米析出相时效强化的定量调控研究

Al-Cu-Mg合金作为结构材料广泛应用在大飞机和高铁等领域。该合金是典型的时效强化合金，然而合金中析出相尺寸小，分布形态多样，微观结构与性能和热处理工艺目标的定量关系不明确，析出强化定量调控仍然是亟待解决的重要科学问题。本项目拟采用第一性原理计算、从头分子动力学以及高分辨透射电镜技术（HAADF-STEM、TF-EWR和3D-ET）优化设计合金中纳米尺度典型析出相界面结构、模拟析出相与位错的交互作用和测定纳米析出相微观结构、尺寸和体积分数，揭示交互作用机理，获得析出相对位错的阻碍作用力及其随尺寸的变化关系数据库；探索该合金中典型析出相强化与析出相种类、尺寸和体积分数之间的函数关系，预测最优析出相分布，明确热处理微观结构调控目标，实现定量调控合金力学性能。析出强化定量调控是金属合金中的共性科学问题，该问题的解决有助于设计新可热处理合金和提高热处理工艺效率。

Al-Cu-Mg alloys as structural materials are typical aging-hardening alloys widely used in area of large aircraft and high-speed railway and other fields. However, the precipitates in this alloys are very small and the distribution of precipitates are complex, so that the goal of heat treatment is not clear, leading to quantitatively tailoring precipitation hardening is still an important scientific topic but difficult to solve. Therefore, in this project, we use first-principles calculations to relax the interfaces structure between the precipitates and matrix. Then, we employ ab initio molecular dynamics to study the complex interaction between dislocations and typical precipitates, to figure out the mechanism of interaction at atomic scale and the obstacle forces from dislocation interact with different size of precipitates. At last, high resolution electron microscopy techniques as HAADF-STEM, TF-EWR and 3D-ET would be used to determine the structure, size and volume fraction of typical precipitates in the alloy. We aim to establish a new precipitation hardening function with respect to the type, the size and the volume fraction of precipitates. From the function, we would obtain an optional combination of precipitates, which act as the heat treatment goal in the aging-hardening processing, and finally achieve quantitatively tailoring the mechanism of the alloys. Quantitatively tailoring precipitation hardening of metal alloys is a common scientific issue, doing this would help to design new aging-hardening alloys and improve the efficiency of heat treatment.