Soft-Mode Parameter as an Indicator for the Activation Energy Spectra in Metallic Glass

Abstract

The activation energy (EA) spectra of potential energy landscape (PEL) provides a convenient perspective for interpreting complex phenomena in amorphous materials; however, the link between the EA spectra and other physical properties in metallic glasses is still mysterious. By systematically probing the EA spectra for numerous metallic glass samples with distinct local geometric ordering, which correspond to broad processing histories, it is found that the shear modulus of the samples are strongly correlated with the arithmetic mean of the EA spectra rather than with the local geometrical ordering. Furthermore, we studied the correlation of the obtained EA spectra and various wellestablished physical parameters. The outcome of our research clearly demonstrates that the soft mode parameter Ψ and the EA spectrum are correlated; therefore, it could be a good indicator of metallic glass properties and sheds important light on the structure-property relationship in metallic glass through the medium of PEL. TOC GraphicMetallic glasses (MGs), as metastable systems, can provide ample opportunity for property control that can be used in structural and functional applications 1-8 . However, due to their inherent nature of disordered atomic packing and, consequently, the absence of conventional defects with distinctive topologies (e.g. dislocations, grain boundaries, etc.), it is very difficult to establish a "crystal clear" structure-property relationship for MGs. In fact, the definition of "defects" in disordered materials are obscure and not unique: examples include free volume (FV) 9-10 , shear transformation zones (STZ) 11-15 , Voronoi tessellation 16-17 , flow units 18-20 , soft modes/spots 21-23 , regions with large fluctuations of atomic level stresses 24-26 , etc. Tremendous efforts have been made in the past to examine the correlations between the local atomic relaxations and those "defects" 21, 27-30 . On the other hand, it is known that many macroscopic properties of MGs (e.g.heat release/absorption 31-32 , homogeneous deformation 18 , etc.) are actually governed by the overall structural distributions and activation energy (EA) spectra, rather than by some extreme "defects", which are located near the ends of the spectra. From the PEL perspective, the relaxation process can be pictured as the transitions between the deep 'metabasins', whereas the relaxation process refers to the elementary hopping event between the 'sub-basins'coded within a metabasin. These processes are related to many important properties, such as glass transition, deformation, aging and rejuvenation etc., of MGs. Systematically analyzing the activation energy (EA) spectra for these processes are extremely helpful for understanding some critical phenomena 33 , and establishing the microscopic structure-property connections. Therefore, important questions that follow and yet remain open are: how does the EA spectra correlate with the physical properties of interest in MGs, and what are the most effective structural indicators in determining...

Metastable grain boundaries: the roles of structural and chemical disorders in their energetics, non-equilibrium kinetic evolution, and mechanical behaviors

“…energetic characteristics of GBs rather than their specific morphologies exert a greater influence on the strength and mobility [51]. Notably, such significant role of inherent energy in nanocrystalline systems have been identified in amorphous materials as well [30,[52][53][54].…”

Identifying packing features of atoms with distinct dynamic behaviors in metallic glass by machine-learning method

“…S4). Furthermore, we analyze the local configurational anisotropy, |u i |, defining the deviation from the center of atom i to the centroid of its corresponding Voronoi cell [32][33][34]. For atoms in full icosahedra, the center of the atom and the corresponding Voronoi cell centroid coincide and |u i |=0.…”

“…However, for atoms in distorted polyhedra, the atom's center deviates from the centroid of corresponding Voronoi polyhedron. Therefore, the local configurational anisotropy signifies the degree of symmetry breaking of atomic environment and thus the propensity for vibrations [32][33][34][35][36]. As shown in Fig.…”

Depicting Defects in Metallic Glasses by Atomic Vibrational Entropy

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