Heredity of Cluster in the Rapid Solidification of Liquid Ta and Its Correlation with Local Symmetry

Metallic glasses (MGs) have received intensive attention in the fields of amorphous physics and materials science owing to its excellent mechanical properties, good corrosion resistance, and large elastic deformation limits. Compared with traditional oxide glasses, the limited glass-forming ability (GFA) seriously restricts the application of MGs in engineering. Therefore, the GFA has been a hot scientific issue in the field of amorphous material research. Recently, scientists have fully realized that GFA is closely related to the local atomic structures in liquid as well as their evolution features. Since the MG is called the "freezing" liquid, exploring the correlation between local atomic structures between liquid and solid phases under rapid solidification conditions is helpful to understand the microstructural mechanism of GFA. Therefore, the rapid solidification process of liquid Ta was investigated via molecular dynamics simulation. The pair correlation function (PDF), the largest standard cluster (LSC), and the reverse atomic trajectory tracking methods were used to characterize and analyze the microstructure and its evolution during the rapid solicitation of liquid Ta. The results showed that the local atomic configurations of the rapidly solidified Ta were various Kasper clusters as well as their distorted configurations, among of which [1/444, 10/555, 2/666] deformed icosahedron (or Z13 cluster) accounts for the highest proportion. The trend of hereditary ability of clusters revealed by the onset temperature of continuous heredity is consistent well with that did by the fraction of staged heredity. The geometric symmetry of clusters can be quantitatively characterized using the local symmetry parameter (LSP). The hereditary ability of clusters is closely related to their LSP. The local five-fold symmetry is beneficial for enhancing hereditary ability, while local four- and six-fold symmetry are disadvantageous for that. The probability of clusters with the same LSC index emerging in the energy range follows the Gaussian distribution, and the expected average atomic potential energy E_exp^j is almost linearly related to the LSP, and E_exp^j decreases with the increase of LSP₅. The high local five-fold symmetry reduces the average atomic potential energy of LSC, thereby enhancing its configurational heredity. These findings have guiding significance for the improvement of GFA through regulating the local symmetry of liquid monatomic metals or alloys.