Professor Wu Guohua's team has made important progress in the aging mechanism of mg-Li alloys.

Recently, Professor Wu Guohua of the National Engineering Research Center of Light Alloy Precision forming of Shanghai Jiaotong University has made important progress in the research on the aging mechanism of mg-Li alloys. The research results, entitled "Origin of the age-hardening and age-softening response in Mg-Li-Zn based alloys", were published in the top international academic journal "Acta Materialia" in the field of metal materials (the original link is https://www.sciencedirect.com/science/article/pii/S1359645422000593), This paper is also the first paper on the aging mechanism of mg-Li alloy published in Acta Materialia. Dr. Ji Hao is the first author of the article, and Professor Wu Guohua and Associate researcher Liu Wencai are the co-authors of the article. The research is supported by the National Natural Science Foundation of China and the Joint Fund for equipment pre-Research and Aerospace Science and Technology.

Mg-Li alloy has the advantages of low density, high specific stiffness and specific strength, good electromagnetic shielding and damping properties, and can be widely used in aerospace, electronics and other fields to replace part of aluminum alloy and common magnesium alloy as structural / functional parts. play a role in further structural weight reduction. However, due to the bottleneck problems such as aging softening of mg-Li alloys, the application of mg-Li alloys is still very limited. Mg-Li-Zn-based alloy is a mg-Li alloy system developed in recent years with good comprehensive mechanical properties and application prospects. However, at present, the characterization of the precipitated phase structure, the phase transformation during aging and its effect on the mechanical properties of Mg-Li-Zn-based alloys are not clear. Therefore, an in-depth study of the aging precipitation behavior of Mg-Li-Zn-based alloys and revealing their age-hardening and softening mechanisms can provide a theoretical basis for the design and application of high-performance mg-Li alloys.

In this study, Professor Wu Guohua's team systematically studied the aging behavior of Mg-10Li (- Zn) (- Er) alloy in different states. With the help of atomic resolution HAADF-STEM technique and other characterization methods and first-principles calculation, it was found that the aging hardening and softening of Mg-10Li-5Zn alloy were mainly related to the evolution of (Mg, Li) 3Zn phase. The crystal structure model of (Mg, Li) 3Zn phase was constructed and the evolution law of morphology and composition during aging was investigated. A new aging mechanism based on (Mg, Li) 3Zn phase transformation in Mg-Li-Zn-based alloy was proposed. It is found that the addition of Er element can hinder the evolution of (Mg, Li) 3Zn phase during low-temperature aging and improve the low-temperature aging stability of Mg-Li-Zn-based alloy. The new aging mechanism based on (Mg, Li) 3Zn phase transformation in Mg-Li-Zn-based alloys proposed in this study provides a theoretical basis for in-depth analysis of the aging behavior of mg-Li alloys and the design of thermally stable mg-Li alloys.

In recent years, with the strong support of Academician Ding Wenjiang, Professor Wu Guohua's team has made a series of research achievements in the development and strengthening and toughening mechanism of mg-Li alloy materials, successfully developed two series of mg-Li alloy materials Mg-Li-Zn-Er and Mg-Li-Al-Zn-Y, and deeply studied their processing technology, strengthening and toughening and aging mechanism, which is expected to be widely used in aerospace and electronic products. Significantly save energy and provide strong support for the realization of China's carbon peak carbon neutralization goal.