Simulation Study Of Topological Dense-packed Nanoclusters Of Mg-Al-Zn Allo

Mg-Al-Zn alloy has excellent properties such as light weight,high strength,heat dissipation performance and electromagnetic interference resistance.It is widely used in 3C products,electromagnetic covers in aerospace,radar and electronic devices and other electronic material fields.In the trend of 3C products and electronic devices towards light,thin,short and small,the number of products and devices using Mg-Al-Zn alloys as electronic materials is increasing.To accelerate the preparation and deep processing of Mg-based alloys,it is particularly important to explore the microstructural evolution and deformation behavior of Mg-based alloys under mechanical conditions during solidification.In this paper,based on molecular dynamics simulations of the evolution of microstructure and deformation behavior of Mg₈₈Al₆Zn₆alloy under the action of rapid solidification process and mechanical conditions,atomic average potential energy,two-body distribution function,maximum standard cluster analysis method,and 3D visualization are used to explore the regularity of microstructure evolution and the correlation between structure and properties mechanical stretching process.Firstly,molecular dynamics simulations of the rapid solidification process of Mg₈₈Al₆Zn₆alloy at a cooling rate of 10¹¹K/s were performed to study the evolution of structural features and structural stacking patterns of topologically close-packed and defective topologically close-packed clusters,and it was found that both types of clusters have similar structural features and play a key role in amorphous formation.The clusters connected by intercross-sharing（IS）have the densest stacking characteristics and the clusters prefer S555bonding in the IS connection,but the tendency is weakened with decreasing temperature.There are five basic connection configurations of nanoclusters,which interpenetrate to form super-sized cluster networks.Secondly,the cluster correlation index was introduced to further investigate the kinetic characteristics and genetic stability of the most densely packed nanoclusters,and the results show that topologically close-packed and defective topologically close-packed clusters occupy about 39.19%of the total number of clusters in the system with a very small number of types at 300 K.The representative clusters can be divided into different groups according to the correlation index,and the strongly correlated clusters are more likely to converge together to form large size nano-clusters,which are more compact and have slower dynamics,forming a“structural skeleton”in the slow dynamics region.Finally,the Mg₈₈Al₆Zn₆solid amorphous alloy is mechanically stretched to analyze the deformation behavior of the clusters under applied load.The topologically close-packed cluster with lower potential energy play a key role in enhancing the yield strength,and the nano-cluster structure network formed by the strongly correlated clusters effectively participates in the accumulation of dense structures and increases the ultimate value of the yield strength.The strongly correlated clusters with a“brittleness”character have a slower atomic mobility,which can be broken and difficult to recover by applied load,while the weakly correlated clusters are repeatedly reorganized and exhibit a“sticky”character.