In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy, the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of molecular dynamics simulation. In liquid Mg-rich Mg-Y alloys, the strong Mg-Y interaction is determined, which promotes the formation of fivefold symmetric local structure. For Mg-Zn alloys, the weak Mg-Zn interaction results in the fivefold symmetry weakening in the liquid structure. Due to the coexistence of Y and Zn, the strong attractive interaction is introduced in liquid Mg-Y-Zn ternary alloy, and contributes to the clustering of Mg, Y, Zn launched from Zn. What is more, the distribution of local structures becomes closer to that in pure Mg compared with that in binary Mg-Y and Mg-Zn alloys. These results should relate to the origins of the Y/Zn segregation zone and close-packed stacking mode in LPSO structure, which provides a new insight into the formation mechanism of LPSO structure at atomic level.

中文翻译：

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液态 Mg-Y-Zn 体系中的化学环境和结构排序：熔体从头算分子动力学研究 LPSO 结构的形成机制

为了阐明Mg-Y-Zn合金中LPSO结构的形成机制，借助分子动力学模拟研究了液态富镁Mg-Y-Zn体系中的化学环境和结构有序性。在液态富镁Mg-Y合金中，确定了强的Mg-Y相互作用，促进了五重对称局部结构的形成。对于 Mg-Zn 合金，弱的 Mg-Zn 相互作用导致液体结构的五重对称性减弱。由于Y和Zn的共存，在液态Mg-Y-Zn三元合金中引入了强吸引力相互作用，并有助于从Zn发射的Mg、Y、Zn的团聚。此外，与二元 Mg-Y 和 Mg-Zn 合金相比，局部结构的分布变得更接近纯镁。这些结果应该与LPSO结构中Y/Zn偏析区和密排堆积模式的起源有关，这为原子水平上LPSO结构的形成机制提供了新的见解。