Grain boundary structure search by using an evolutionary algorithm with effective mutation methods

Yang, Chao; Zhang, Mingfei; Qi, Liang

doi:10.1016/j.commatsci.2020.109812

Cited by 17 publications

(5 citation statements)

References 79 publications

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“…The lowest energy structure was used as input for the subsequent diffusion simulations. This optimization procedure recovered the well-known structures of the Σ3 and Σ17 GBs, but it did not sample different GB densities as in more sophisticated optimization routines [48][49][50] .…”

Section: Methodsmentioning

confidence: 99%

Point-defect avalanches mediate grain boundary diffusion

Chesser

2022

Commun Mater

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Grain boundary diffusion in polycrystalline materials is a physical phenomenon of great fundamental interest and practical significance. Although accelerated atomic transport along grain boundaries has been known for decades, atomic-level understanding of diffusion mechanisms remains poor. Previous atomistic simulations focused on low temperatures where the grain boundary structure is ordered or high temperatures where it is highly disordered. Here, we conduct molecular dynamics simulations of grain boundary diffusion at intermediate temperatures most relevant to applications. A surprising result of this work is the observation of intermittent GB diffusion behavior and its strong system-size dependence unseen in previous work. Both effects are found to originate from thermally activated point-defect avalanches. We identify the length and time scales of the avalanches and link their formation to dynamic heterogeneity in partially disordered systems. Our findings have implications for future computer modeling of grain boundary diffusion and mass transport in nano-scale materials.

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Section: Methodsmentioning

confidence: 99%

Point-defect avalanches mediate grain boundary diffusion

Chesser

2022

Commun Mater

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“…A congruent GB phase transition is characterized by transformations limited to the GB core without a change in grain misorientation and GB plane 12 . These transitions have mostly been studied using atomistic modeling of [001] tilt GBs in fcc copper 15,24,25 , in various tungsten GBs 26 , and magnesium 27 . Recently, two different GB phases were observed experimentally in Σ19b h1 1 1i f1 7 8g GBs in copper by atomic resolution scanning transmission electron microscopy (STEM) 28 .…”

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confidence: 99%

Dual phase patterning during a congruent grain boundary phase transition in elemental copper

et al. 2022

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The phase behavior of grain boundaries can have a strong influence on interfacial properties. Little is known about the emergence of grain boundary phases in elemental metal systems and how they transform. Here, we observe the nanoscale patterning of a grain boundary by two alternating grain boundary phases with distinct atomic structures in elemental copper by atomic resolution imaging. The same grain boundary phases are found by computational grain boundary structure search indicating a first-order transformation. Finite temperature atomistic simulations reveal a congruent, diffusionless transition between these phases under ambient pressure. The patterning of the grain boundary at room temperature is dominated by the grain boundary phase junctions separating the phase segments. Our analysis suggests that the reduced mobility of the phase junctions at low temperatures kinetically limits the transformation, but repulsive elastic interactions between them and disconnections could additionally stabilize the pattern formation.

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“…(Replotted after Hu et al, Mater Today, [114] Copyright 2020, Elsevier.) such as evolutionary algorithms, [150][151][152] convolutional neural networks, [153] other machine learning algorithms, [154][155][156][157][158][159] have been used to predict GB structures and other properties. These methods have not yet been used to compute GB diagrams, but they certainly have great potential for future applications in this field.…”

Section: Predicting Gb Properties In 7-d For a Binary Alloy Consideri...mentioning

confidence: 99%

Computing grain boundary “phase” diagrams

Luo

2023

Interdisciplinary Materials

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Grain boundaries (GBs) can be treated as two‐dimensional (2‐D) interfacial phases (also called “complexions”) that can undergo interfacial phase‐like transitions. As bulk phase diagrams and calculation of phase diagram (CALPHAD) methods serve as a foundation for modern materials science, we propose to extend them to GBs to have equally significant impacts. This perspective article reviews a series of studies to compute the GB counterparts to bulk phase diagrams. First, a phenomenological interfacial thermodynamic model was developed to construct GB lambda diagrams to forecast high‐temperature GB disordering and related trends in sintering and other properties for both metallic and ceramic materials. In parallel, an Ising‐type lattice statistical thermodynamic model was utilized to construct GB adsorption (segregation) diagrams, which predicted first‐order GB adsorption transitions and critical phenomena. These two simplified thermodynamic models emphasize the GB structural (disordering) and chemical (adsorption) aspects, respectively. Subsequently, hybrid Monte Carlo and molecular dynamics atomistic simulations were used to compute more rigorous and accurate GB “phase” diagrams. Computed GB diagrams of thermodynamic and structural properties were further extended to include mechanical properties. Moreover, machine learning algorithms were combined with atomistic simulations to predict GB properties as functions of four independent compositional variables and temperature in a 5‐D space for a given GB in high‐entropy alloys or as functions of five GB macroscopic (crystallographic) degrees of freedom plus temperature and composition for a binary alloy in a 7‐D space. Other relevant studies are also examined. Future perspective and outlook, including two emerging fields of high‐entropy grain boundaries (HEGBs) and electrically (or electrochemically) induced GB transitions, are discussed.

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Grain boundary structure search by using an evolutionary algorithm with effective mutation methods

Cited by 17 publications

References 79 publications

Point-defect avalanches mediate grain boundary diffusion

Point-defect avalanches mediate grain boundary diffusion

Dual phase patterning during a congruent grain boundary phase transition in elemental copper

Computing grain boundary “phase” diagrams

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