基于Ag界面偏聚浓度调控的Al-Mg-Si-Ag合金强韧化机制研究

Ag是Al-Mg-Si合金中典型的微合金化元素，Ag原子可以通过偏聚在析出相界面处提高析出相的形核率和热稳定性，从而改善合金的力学性能。然而，Ag原子界面偏聚往往存在偏聚浓度低且分布不均匀等问题，导致合金性能提升不足。实现溶质原子界面偏聚浓度的精确调控对于提高合金的时效硬化潜力具有非常积极的意义。本项目通过设计一系列不同Ag含量的Al-Mg-Si-Ag合金，采用先进的电子显微表征技术、模拟计算和力学性能测试，系统研究合金中各个析出相的界面精细结构及Ag原子偏聚规律，揭示合金成分和时效温度对Ag界面偏聚浓度的影响规律和作用机理，建立“Ag界面偏聚浓度—析出相尺寸形貌—合金力学性能”之间的关联规律，通过协同调控合金成分和时效工艺，实现对Ag界面偏聚浓度的有效控制，从而显著提高合金的时效硬化潜力。本项目为提高Al-Mg-Si合金的力学性能提供新思路，为新型高强高韧汽车车身板的开发奠定基础。

Ag is a typical microalloying element added in Al-Mg-Si alloys. The addition of Ag can increase the nucleation rate and thermal stability of precipitates by segregated at the precipitate/matrix interface, thus improve the mechanical properties of the alloys. However, the low Ag segregation concentration and its uneven distribution lead to the insufficient improvement of properties. Accurate control of solute atoms interfacial segregation concentration is of great significance in improving the age hardening potential. In the present proposal, a series of Al-Mg-Si alloys with different Ag additions are designed, advanced electron microscopy characterization, simulation calculation and mechanical testing are used to: study the interfacial structures of precipitates and the segregation mechanism of Ag atoms, reveal the influence mechanism of the alloy composition and aging temperature on Ag interfacial segregation concentration, establish the relationship between Ag interfacial segregation concentration, precipitate morphology, and mechanical properties of the Al-Mg-Si alloy. By synergistic regulation of alloy composition and aging process, the Ag interfacial segregation concentration is expected to be controlled, which can significantly improve the aging hardening potential of the alloy. This project provides a new idea for improving the mechanical properties of Al-Mg-Si alloy and lays a foundation for the development of new high-strength and high-tough alloy for automobile body application.