Direct observation of strain-induced non-equilibrium grain boundaries

Straumal, Boris B.; Kogtenkova, O. A.; Muktepavela, F.; Kolesnikova, K. I.; Булатов, М. Ф.; Straumal, P. B.; Baretzky, B.

doi:10.1016/j.matlet.2015.07.038

Cited by 10 publications

(4 citation statements)

References 11 publications

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“…For cubic crystalline materials, the grain envelope is characterized by a quadrilateral shape in 2D case and an octahedral shape in 3D case. Only the nucleation and growth of the primary solid phase is considered, and the grain boundary wetting [24,25] is ignored. As shown in Figure 1b, the CA and FE grids are completely superimposed.…”

Section: Model Descriptionsmentioning

confidence: 99%

Direct Macroscopic Modeling of Grain Structure and Macrosegregation with a Cellular Automaton–Finite Element Model

Chen

Shen

2019

Metals

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Grain structure and macrosegregation are two main factors determining mechanical properties of components and are strongly coupled during alloy solidification. A two-dimensional (2D) cellular automaton (CA)–finite element (FE) model is developed to achieve a direct macroscopic modeling of grain structure and macrosegregation during the solidification of binary alloys. With the conservation equations of mass, momentum, energy, and solute solved by a macroscopic FE model and the grain structure described by a microscopic CA model, a two-way coupling between the CA and FE models is applied. Furthermore, the effect of the fluid flow on the dendrite tip growth velocity is considered by modified dendrite tip growth kinetics. The CAFE model is applied to a quasi-2D benchmark solidification experiment of a Sn–3.0wt.%Pb alloy, and the grain structure and macrosegregation are predicted simultaneously. It is demonstrated that the model has a capacity to describe the undercooling ahead of the growth front. The growth directions of columnar grains, grain sizes, and columnar-to-equiaxed transition (CET) position are obviously modified by the fluid flow, and obvious segregated channels almost aligned with the orientations of the columnar grains are found. Qualitatively good agreement is obtained between the predicted segregation profiles and experimental measurements.

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Section: Model Descriptionsmentioning

confidence: 99%

Direct Macroscopic Modeling of Grain Structure and Macrosegregation with a Cellular Automaton–Finite Element Model

Chen

Shen

2019

Metals

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“…The existence of nonequilibrium GBs after SPD processing has been supported by strain mapping results in a SPD Pd–Ag alloy, in which the GB thickness (with evident strain) is determined to be ≈1.5 nm and is markedly larger than the thickness of relaxed GBs (≈0.5 nm) [ 24 ]. In addition, the higher energy of nonequilibrium GBs as compared to conventional GBs has been demonstrated by the transformation of partial to complete GB wetting in Sn–Pb alloys during continuous strain by Straumal et al [ 25 ]. However, this notion was confused by two works in the SPD Cu and Cu–Pb alloy [ 26 – 27 ], in which various defects such as vacancy agglomerations, nanometer- and micrometer-sized voids were observed.…”

Section: Reviewmentioning

confidence: 99%

Diffusion and surface alloying of gradient nanostructured metals

Wang¹,

Lu²

2017

Beilstein J. Nanotechnol.

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Gradient nanostructures (GNSs) have been optimized in recent years for desired performance. The diffusion behavior in GNS metals is crucial for understanding the diffusion mechanism and relative characteristics of different interfaces that provide fundamental understanding for advancing the traditional surface alloying processes. In this paper, atomic diffusion, reactive diffusion, and surface alloying processes are reviewed for various metals with a preformed GNS surface layer. We emphasize the promoted atomic diffusion and reactive diffusion in the GNS surface layer that are related to a higher interfacial energy state with respect to those in relaxed coarse-grained samples. Accordingly, different surface alloying processes, such as nitriding and chromizing, have been modified significantly, and some diffusion-related properties have been enhanced. Finally, the perspectives on current research in this field are discussed.

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“…This fact can be observed, for example, using GB grooving phenomenon in multiphase materials, i.e. the high-energetical GBs tends to be substituted by two interphase boundaries (IBs) of lower energies [4]. Along with GBs, non-equilibrium IBs with the increased energies are also expected in deformed materials.…”

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confidence: 96%

“…Later the idea of non-equilibrium GBs has been extensively used in order to describe the unique properties of nanograined materials manufactured by SPD [1,2]. The additional defects formed during plastic deformation increase the GB energy in comparison with equilibrium values [4]. This fact can be observed, for example, using GB grooving phenomenon in multiphase materials, i.e.…”

mentioning

confidence: 99%