Revealing Grain Boundary Sliding from Textures of a Deformed Nanocrystalline Pd–Au Alloy

Tóth, László; Skrotzki, Werner; Zhao, Yajun; Pukenas, Aurimas; Braun, Christian; Birringer, R.

doi:10.3390/ma11020190

Cited by 14 publications

(11 citation statements)

References 16 publications

(30 reference statements)

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“…The GR model that is used is based on the Taylor deformation mode of the polycrystal. This is in accordance with recent proposition, that, at very large strains, the polycrystal behavior approaches the Taylor mode . It was found in the study by Toth et al that the density of geometrically necessary dislocations decreases at very large strains.…”

Section: Resultssupporting

confidence: 93%

Modeling of Crystallographic Texture in Plastic Flow Machining

Tóth

Beygelzimer

et al. 2019

Adv Eng Mater

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Plastic flow machining (PFM) is proposed as a new severe plastic deformation (SPD) technique capable of producing ultrafine‐grained sheet metal from bulk sample. Herein, a model is proposed for the three strain paths that the material follows during the PFM extrusion process. The proposed strain paths are justified by modeling the texture evolution in good agreement with the experiments in the three deformation zones. Two polycrystal models are used to simulate texture evolution: the viscoplastic self‐consistent (VPSC) polycrystal approach and the Taylor‐type lattice curvature‐based grain fragmentation (GR) model. The simulations reproduce faithfully all three textures observed experimentally within the sheet. The experimental texture in the zone carrying the smallest strain is obtained with the VPSC approach, whereas in the higher strain region, the GR model reproduced the texture. The two main results of this modeling are as follows: 1) an example is presented for the successful identification of the deformation mode in a new SPD process with the help of the crystallographic texture. 2) At large strains, the VPSC model fails; it is the Taylor deformation‐based GR approach which is able to reproduce the experimental texture evolution.

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Section: Resultssupporting

confidence: 93%

Modeling of Crystallographic Texture in Plastic Flow Machining

Tóth

Beygelzimer

et al. 2019

Adv Eng Mater

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“…At a certain shear strain twinning ceases, may be because grain boundary sliding takes over as the deformation mechanism. A supporting indication of this is the further randomization of texture [29,30]. The generally low texture strength may be also caused by twinning.…”

Section: Microstructure Developmentmentioning

confidence: 96%

“…Twinning may have led to the almost equal intensities of the twinning related A 1 * and A 2 * shear components. Recent simulations also show that grain boundary sliding leads to randomization of the texture while maintaining the texture signature [29,30]. Thus, grain boundary sliding in the nano-grained HEA during RT-HPT may have led to the weak texture observed.…”

Section: Texture Formationmentioning

confidence: 97%

Microstructure, Texture, and Strength Development during High-Pressure Torsion of CrMnFeCoNi High-Entropy Alloy

et al. 2020

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The equiatomic face-centered cubic high-entropy alloy CrMnFeCoNi was severely deformed at room and liquid nitrogen temperature by high-pressure torsion up to shear strains of about 170. Its microstructure was analyzed by X-ray line profile analysis and transmission electron microscopy and its texture by X-ray microdiffraction. Microhardness measurements, after severe plastic deformation, were done at room temperature. It is shown that at a shear strain of about 20, a steady state grain size of 24 nm, and a dislocation density of the order of 1016 m−2 is reached. The dislocations are mainly screw-type with low dipole character. Mechanical twinning at room temperature is replaced by a martensitic phase transformation at 77 K. The texture developed at room temperature is typical for sheared face-centered cubic nanocrystalline metals, but it is extremely weak and becomes almost random after high-pressure torsion at 77 K. The strength of the nanocrystalline material produced by high-pressure torsion at 77 K is lower than that produced at room temperature. The results are discussed in terms of different mechanisms of deformation, including dislocation generation and propagation, twinning, grain boundary sliding, and phase transformation.

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“…According to the classification by Estrin and Kubin [ 81 ], the stability of the M type is due to that the local lattice orientation becoming unstable to activate the slip system. Here, the nucleation of the deformation band (grain) is some related to the GB splitting to activate the slip system under the strain, and the deformation band extension is related to the change of the local lattice orientation due to the instability of the orientation [ 82 ].…”

Section: Simulation Results and Discussionmentioning

confidence: 99%

A Study of Strain-Driven Nucleation and Extension of Deformed Grain: Phase Field Crystal and Continuum Modeling

et al. 2018

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The phase-field-crystal (PFC) method is used to investigate migration of grain boundary dislocation and dynamic of strain-driven nucleation and growth of deformed grain in two dimensions. The simulated results show that the deformed grain nucleates through forming a gap with higher strain energy between the two sub-grain boundaries (SGB) which is split from grain boundary (GB) under applied biaxial strain, and results in the formation of high-density ensembles of cooperative dislocation movement (CDM) that is capable of plastic flow localization (deformed band), which is related to the change of the crystal lattice orientation due to instability of the orientation. The deformed grain stores the strain energy through collective climbing of the dislocation, as well as changing the orientation of the original grain. The deformed grain growth (DGG) is such that the higher strain energy region extends to the lower strain energy region, and its area increase is proportional to the time square. The rule of the time square of the DGG can also be deduced by establishing the dynamic equation of the dislocation of the strain-driven SGB. The copper metal is taken as an example of the calculation, and the obtained result is a good agreement with that of the experiment.

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Revealing Grain Boundary Sliding from Textures of a Deformed Nanocrystalline Pd–Au Alloy

Cited by 14 publications

References 16 publications

Modeling of Crystallographic Texture in Plastic Flow Machining

Modeling of Crystallographic Texture in Plastic Flow Machining

Microstructure, Texture, and Strength Development during High-Pressure Torsion of CrMnFeCoNi High-Entropy Alloy

A Study of Strain-Driven Nucleation and Extension of Deformed Grain: Phase Field Crystal and Continuum Modeling

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