Review on Micro-Alloying and Preparation Method of 7xxx Series Aluminum Alloys: Progresses and Prospects

Notably, 7xxx series aluminum alloy has become the most popular nonferrous alloy, extensively used in industry, construction and transportation trades, due to its high comprehensive properties such as high static strength, high strength, heat resistance, high toughness, damage resistance, low density, low quenching sensitivity and rich resource. The biggest challenge for aluminum alloy today is to greatly improve the corrosion resistance of the alloy, while maintaining its strength. The preparation method of 7xxx series aluminum alloy requires controlling time lapses in the process of heating, holding and cooling, and there are many species precipitates in the crystal, but the precipitated strengthening phase is a single type of equilibrium η′ phase. Therefore, more attention should be paid to how to increase the volume fraction of η′ precipitates and modify the comprehensive performance of the material and focus more on the microstructure of the precipitates. This article reviews the progress of 7xxx series aluminum alloy materials in micro-alloying, aging precipitation sequence, the strengthening-toughening mechanism and the preparation method. The effect of adding trace elements to the microstructure and properties of 7xxx series aluminum alloy and the problems existing in aging precipitation characteristics and the reinforcement mechanism are discussed. The future development direction of 7xxx series aluminum alloy is predicted by developing a method for the process-microstructure-property correlation of materials to explore the characteristic microstructure, micro-alloying, controlling alloy microstructure and optimizing heat-treatment technology.