The study of viscosity, supercooling and short-range order in quasi-crystallizing melts of the Al-Cu-Fe system is of considerable interest for understanding the processes of formation of the quasi-crystalline structure. The viscosity of the melt is a key parameter determining its ability to crystallize and form an amorphous or quasi-crystalline state. High viscosity prevents diffusion of atoms and promotes supercooling of the melt.
Melt supercooling, in turn, plays an important role in the formation of a quasi-crystalline structure. With sufficiently deep supercooling, metastable phases can form, including quasi-crystals. The short-range order in the melt, i.e. the nature of the arrangement of atoms at short distances, also affects crystallization processes. If the short-range order in the melt corresponds to the structure of a quasi-crystal, then the probability of its formation increases.
A thorough understanding of the relationships between liquid and solid state properties is a key factor in the development of innovative solid materials, including glasses, quasicrystals, and high-entropy alloys. In this paper, we explore this relationship using Al-Cu-Fe alloys as an example, which represent a convenient model for studying the microscopic processes of quasicrystal formation.
We conduct an experimental study of two structure-sensitive liquid parameters – viscosity and degree of supercooling – and compare the obtained data with the results of ab initio short-range order (SRO) modeling. It is found that the key characteristics of interatomic interactions in the Al-Cu-Fe system, obtained on the basis of the radial distribution function and the bond angle distribution function, remain unchanged during the transition from the liquid to the solid state. In particular, a distinct effective repulsion between Fe and Cu atoms is observed, as well as a strong chemical interaction between Fe and Al.
The analysis of the orientational BP demonstrates the presence of icosahedral clusters with a central Fe atom in the supercooled liquid. According to the literature, these clusters are structural elements of the quasi-crystalline phase. In the concentration range corresponding to the composition of the icosahedral phase, the viscosity and supercooling isotherms show minima that have a significant effect on the initial stages of solidification.
Based on the obtained results, we conclude that structure-sensitive characteristics of the melt can serve as valuable indicators of solid phase formation.
Studies of viscosity, supercooling and short-range order in Al-Cu-Fe melts have shown that these parameters depend on the alloy composition and temperature. In particular, it was found that melts close in composition to the stable icosahedral quasicrystal Al62Cu25.5Fe12.5 have increased viscosity and a tendency to supercooling. Computer modeling methods make it possible to study short-range order in melts and identify correlations between the melt structure and its ability to form a quasicrystalline phase.
Author: L. V. Kamaeva, R. E. Ryltsev, V. V. Lad’yanov, N. M. Chtchelkatchev
Institute: Udmurt Federal Research Center of the Ural Branch of the Russian Academy of Sciences, Izhevsk, 426068, Russia, L. F. Vereshchagin Institute of High Pressure Physics of the Russian Academy of Sciences, Troitsk 108840, Moscow, Russia, Institute of Metallurgy, Ural Branch, Russian Academy of Sciences, 620016, Yekaterinburg, Russia, Ural Federal University, 620002, Yekaterinburg, Russia, Moscow Institute of Physics and Technology, 141700, Dolgoprudny, Moscow Region, Russia