Understanding the anomalous thermal behavior of Σ3 grain boundaries in a variety of FCC metals

Chesser, Ian; Holm, Elizabeth A.

doi:10.1016/j.scriptamat.2018.07.011

Cited by 24 publications

(10 citation statements)

References 44 publications

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“…This case again consists of a triple junction, as described by Figure 20 . We performed simulations with a constant GB mobility set to

= 1

, taken from [ 74 ], a domain of

, and a time step of

= 5

s. The Aniso formulation is used by considering

as only initially defined by the mis-orientation and then also dependent on the inclination (obtained through the GB5DOF code and denoted as Aniso-GB5DOF). The Iso, Het, and HetGrad are not presented here because they evolve in the wrong direction (the expected movement should reduce the length of the interface between grain

and

, depicted in yellow).…”

Section: Accounting For Mis-orientation and Inclination Dependencementioning

confidence: 99%

Comparative Study and Limits of Different Level-Set Formulations for the Modeling of Anisotropic Grain Growth

et al. 2021

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In this study, four different finite element level-set (FE-LS) formulations are compared for the modeling of grain growth in the context of polycrystalline structures and, moreover, two of them are presented for the first time using anisotropic grain boundary (GB) energy and mobility. Mean values and distributions are compared using the four formulations. First, we present the strong and weak formulations for the different models and the crystallographic parameters used at the mesoscopic scale. Second, some Grim Reaper analytical cases are presented and compared with the simulation results, and the evolutions of individual multiple junctions are followed. Additionally, large-scale simulations are presented. Anisotropic GB energy and mobility are respectively defined as functions of the mis-orientation/inclination and disorientation. The evolution of the disorientation distribution function (DDF) is computed, and its evolution is in accordance with prior works. We found that the formulation called “Anisotropic” is the more physical one, but it could be replaced at the mesoscopic scale by an isotropic formulation for simple microstructures presenting an initial Mackenzie-type DDF.

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“…This case again consists of a triple junction, as described by Figure 20 . We performed simulations with a constant GB mobility set to

= 1

, taken from [ 74 ], a domain of

, and a time step of

= 5

s. The Aniso formulation is used by considering

and

, depicted in yellow).…”

Section: Accounting For Mis-orientation and Inclination Dependencementioning

confidence: 99%

Comparative Study and Limits of Different Level-Set Formulations for the Modeling of Anisotropic Grain Growth

et al. 2021

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“…Dillon et al discovered that a complexion transition in Nd‐doped Al 2 O 3 resulted in abnormal grain growth, when a fraction of the boundaries transitioned to a complexion of higher mobility. (Appendix describes another type of complexion transition that can lead to abnormal grains …”

Section: Controlling Grain Boundariesmentioning

confidence: 99%

Review of grain boundary complexion engineering: Know your boundaries

et al. 2018

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Grain boundary structure-property relationships influence bulk performance and, therefore, are an important criterion in materials design. Materials scientists can generate different grain boundary structures by changes in temperature, pressure, and chemical potential because interfaces attain their own equilibrium states, known as complexions. Complexions undergo first-order transitions by changes in thermodynamic variables, which results in discontinuous changes in properties.Grain boundary complexion engineering is introduced in this paper as a method for controlling complexion transitions to improve material performance. This International Conference on Sintering 2017 lecture describes the tools for grain boundary complexion engineering: complexion equilibrium and time-temperaturetransformation (TTT) diagrams. These tools can be implemented in processing design to tailor grain boundary properties, including grain boundary mobility.While impactful, these diagrams are often limited in scope because they are currently empirically derived. This article discusses how measurement techniques can be combined with data analytical methods to build mechanistically derived complexion equilibrium and TTT diagrams.

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“…Next, we consider the motion of the highly mobile Σ3 (1 1 0) twist GB and argue that this GB is close to satisfying the optimal transport model assumptions (D < 1). Prior MD calculations for this GB indicate a very small energy barrier to motion associated with partial dislocation glide [64][65][66]. General Σ3 GBs that migrate via {1 1 0} facet motion have mobilities orders of magnitude larger than other Σ3 GBs and among the highest mobilities in the 388 FCC Ni GB mobility survey [15].…”

Section: Testing the Min-shuffle Hypothesis For Twist Gb Migrationmentioning

confidence: 99%

“…General Σ3 GBs that migrate via {1 1 0} facet motion have mobilities orders of magnitude larger than other Σ3 GBs and among the highest mobilities in the 388 FCC Ni GB mobility survey [15]. For these GBs, mobility attains a maximum at cryogenic temperatures and decreases with increasing temperature, similar to phonon damped dislocation glide [64,66,67]. In this work, the Σ3 (1 1 0) GB is found to migrate via the min-shuffle transformation under all simulation conditions tested (free and fixed boundary conditions, 100-1400 K) and has D < 1…”

Section: Testing the Min-shuffle Hypothesis For Twist Gb Migrationmentioning

confidence: 99%

Optimal transportation of grain boundaries: A forward model for predicting migration mechanisms

Chesser,

Holm,

Runnels

2021

Preprint

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It has been hypothesized that the most likely atomic rearrangement mechanism during grain boundary (GB) migration is the one that minimizes the lengths of atomic displacements in the dichromatic pattern. In this work, we recast the problem of atomic displacement minimization during GB migration as an optimal transport (OT) problem. Under the assumption of a small potential energy barrier for atomic rearrangement, the principle of stationary action applied to GB migration is reduced to the determination of the Wasserstein metric for two point sets. In order to test the minimum distance hypothesis, optimal displacement patterns predicted on the basis of a regularized OT based forward model are compared to molecular dynamics (MD) GB migration data for a variety of GB types and temperatures. Limits of applicability of the minimum distance hypothesis and interesting consequences of the OT formulation are discussed in the context of MD data analysis for twist GBs, general Σ3 twin boundaries and a tilt GB that exhibits shear coupling. The forward model may be used to predict atomic displacement patterns for arbitrary disconnection modes and a variety of metastable states, facilitating the analysis of multimodal GB migration data.

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Understanding the anomalous thermal behavior of Σ3 grain boundaries in a variety of FCC metals

Cited by 24 publications

References 44 publications

Comparative Study and Limits of Different Level-Set Formulations for the Modeling of Anisotropic Grain Growth

Comparative Study and Limits of Different Level-Set Formulations for the Modeling of Anisotropic Grain Growth

Review of grain boundary complexion engineering: Know your boundaries

Optimal transportation of grain boundaries: A forward model for predicting migration mechanisms

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