本申请将以Al-Mg-Si超细晶导线材料作为研究对象，以Sc作为微量添加元素，通过双级时效处理形成纳米第二相颗粒晶内/晶界双层级分布的微观组织，对比研究合金成分、微合金元素含量和时效工艺对微观组织演变、时效析出行为以及对强度、电导率和耐热性能的影响。阐明超细晶金属导线材料的双级析出特性；澄清该尺度下微合金化元素的作用机理；探索主合金元素与微合金元素之间可能的相互作用；在此基础上建立超细晶铝合金导线材料微观组织与性能之间的关联并构建相应的理论模型，据此优化相关影响参量以获得优异的综合性能。重点通过微合金量及相应制备工艺的调控，获得晶内纳米Mg2Si相和晶界Al3Sc双层级颗粒分布的微观组织，开发高性能Al-Mg-Si-Sc合金导线材料。研究结果不仅有助于从机理上理解超细晶铝合金导线材料中的时效析出行为及其调控原则，同时也为高强、高导、耐热铝合金导线材料的合金设计和工艺完善提供借鉴和参考。

This project will be focused on ultrafine-grained Al-Mg-Si conductor materials, which are microalloyed by Sc and characterized by microstructural features with intergranular/intragranular dual distributions of nanosized particles, derived from two-stage aging treatment. The effects of composition, microalloying element, and aging treatment on the microstructural evolution, precipitation behaviors as well as on the properties, including strength, electrical conductivity, and heat-resistance property, will be comparatively studied. This project is aimed to (i) demonstrate the two-stage precipitation characteristics in the metal conductor materials with ultrafine-sized grains; (ii) clarify the Sc microalloying mechanism at this length scale; (iii) explore the possible interaction between the microalloying elements and the main alloying elements; and (iv) correlate the microstructures with the properties of the ultrafine-grained Al conductor materials. Corresponding models will be developed to quantitatively describe the relationships between the microstructural parameters and the strength, electrical conductivity, and high-temperature properties, with which the main influencing factors will be artificially controlled to optimize the comprehensive properties. In particular, development of a new kind of high-performance Al-Mg-Si-Sc conductor materials will be centered by controlling the Sc content and promoting the preparing procedures, which have microstructural features with Mg2Si precipitates dispersed within the grain interior and Al3Sc dispersoids located at grain boundaries. These results will be helpful for understanding the precipitation behaviors and their tailoring approaches in ultrafine-grained metal conductor materials. Besides, they will be reference for the alloy design and process optimization of high-strength, high-conductivity, and excellent heat-resistance Al alloy-based conductor materials.