Multiplicity of grain boundary structures and related energy variations

Hallberg, Håkan; Blixt, Kevin Hult

doi:10.1016/j.mtcomm.2023.107724

Cited by 3 publications

(1 citation statement)

References 47 publications

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“…In contrast to idealized equilibrium GBs, metastable GB energies feature large multiplicity due to microscopic degrees of freedom. The existence of metastable GBs results in an energy spectrum in lieu of a single value for a particular misorientation [18,24,25]. By adjusting several variables, including the relative translation of grain, placement of the boundary interface, allowed proximity of atoms before one is selected for deletion, and procedures for deleting overlapping atoms, Homer et al have sampled over 43 million GB structures from 7304 minimum energy GB structures in Al [26].…”

Section: Kinetics and Energetics Of Metastable Gbsmentioning

confidence: 99%

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

He,

Wang,

Fan

2024

J. Phys.: Condens. Matter

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Complex environments in advanced manufacturing usually involve ultrafast laser or ion irradiation which leads to rapid heating and cooling and drives grain boundaries (GBs) to non-equilibrium states, featuring distinct energetics and kinetic behaviors compared to conventional equilibrium or near-equilibrium GBs. In this topical review, we provide an overview of both recent experimental and computational studies on metastable GBs, i.e. their energetics, kinetic behaviors, and mechanical properties. In contrast to GBs at thermodynamic equilibrium, the inherent structure energy of metastable GBs exhibits a spectrum instead of single value for a particular misorientation, due to the existence of microstructural and chemical disorder. The potential energy landscape governs the energetic and kinetic behaviors of metastable GBs, including the ageing/rejuvenating mechanism and activation barrier distributions. The unique energetics and structural disorder of metastable GBs lead to unique mechanical properties and tunability of interface-rich nanocrystalline materials. We also discuss that, in addition to structural disorder, chemical complexity in multi-components alloys could also drive the GBs away from their ground states and, subsequently, significantly impact on the GBs-mediated deformation. And under some extreme conditions such as irradiation, structural disorders and chemical complexity may simultaneously present at interfaces, further enriching of metastability of GBs and their physical and mechanical behaviors. Finally, we discuss the machine learning techniques, which have been increasingly employed to predict and understand the complex behaviors of metastable GBs in recent years. We highlight the potential of data-driven approaches to revolutionize the study of disorder systems by efficiently extracting the relationship between structural features and material properties. We hope this topical review paper could shed light and stimulate the development of new GBs engineering strategies that allow more flexibility and tunability for the design of nano-structured materials.

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Section: Kinetics and Energetics Of Metastable Gbsmentioning

confidence: 99%

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

He,

Wang,

Fan

2024

J. Phys.: Condens. Matter

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Phase field crystal modeling of grain boundary structures in diamond cubic systems

Blixt,

Hallberg

2024

Phys. Rev. Materials

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Phase field crystal (PFC) modeling has proved to be a versatile numerical tool in the analysis of crystalline microstructures. Most often, however, the focus is put on bulk crystal behavior, while crystal defects such as grain boundaries (GBs) are less explored. This is, in particular, the case for crystal structures beyond fcc and bcc. In this work, the possibilities and challenges in adopting PFC to diamond cubic (DC) crystal structures is investigated. Three different PFC models are considered for this purpose. One of them was published previously, and two are modifications proposed in the present work. The models are compared in terms of both DC phase stabilization and their ability to provide relevant GB structures. The models employ combinations of two- and three-point correlations, and the addition of a three-point correlation is found to be required for stabilization of the expected DC GB structures. It is concluded that although each of the models has limitations in terms of the GB structures which can be stabilized and performance in terms of phase stability, key PFC components for successful modeling of DC structures can be identified. Published by the American Physical Society 2024

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Assessing grain boundary variability through phase field crystal simulations

Hallberg,

Hult Blixt

2024

Phys. Rev. Materials

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Characterization of grain boundaries (GBs) typically focuses exclusively on ideal minimum-energy structures, thus offering a limited perspective on the potential structural diversity and related property variations of GBs. In this study, phase field crystal (PFC) simulations are employed to systematically explore alternative GB states through γ-surface sampling. A large number of tilt and twist GBs are examined in both fcc and bcc bicrystal structures. It is demonstrated that identifying variants in GB structure necessitates considering a set of microscopic degrees of freedom (DOF), comprising the components of relative crystal translation, in addition to the GB's five macroscopic DOF. Taking GB energy and excess volume as examples of key GB properties, a significant spread in GB energy is revealed, stemming from variations in the microscopic DOF, while maintaining constant macroscopic DOF. In addition, the significant variations found in GB excess volume and energy when GB variants are considered challenge the common assumption of a strong correlation between them. Taken together, the findings underscore the importance of recognizing a range of GB structures and properties for each macroscopic GB configuration, rather than relying on singular ideal minimum-energy GB structures, as is usually done. Published by the American Physical Society 2024

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Multiplicity of grain boundary structures and related energy variations

Cited by 3 publications

References 47 publications

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

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

Phase field crystal modeling of grain boundary structures in diamond cubic systems

Assessing grain boundary variability through phase field crystal simulations

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