Dislocation substructure in fatigued α-iron single crystals

Krejčí, Jan; Lukáš, P.

doi:10.1002/pssa.2210050204

“…The parameters b and G are taken from Frost and Ashby (1982). The value of ρ 0 is presented by Krejci and Lukas (1971). The latent interaction coefficient A αu is identified and the self-interaction coefficient A αα is obtained by assuming a ratio of 1.4 between latent and self-hardening.…”

Section: Reverse Deformationmentioning

confidence: 99%

Control of size and density of self-assembled Au droplets via systematic deposition amount control on high-index GaAs type-A surfaces

Li¹,

Sui²,

Kim³

et al. 2014

Jpn. J. Appl. Phys.

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Sheet metal forming processes are within the core of many modern manufacturing technologies, as applied in, e.g., automotive and packaging industries. Initially flat sheet material is forced to transform plastically into a three-dimensional shape through complex loading modes. Deviation from a proportional strain path is associated with hardening or softening of the material due to the induced plastic anisotropy resulting from the prior deformation. The main cause of these transient anisotropic effects at moderate strains is attributed to the evolving underlying dislocation microstructures. In this paper, a composite dislocation cell model, which explicitly describes the dislocation structure evolution, is combined with a BCC crystal plasticity framework to bridge the microstructure evolution and its macroscopic anisotropic effects. Monotonic and multi-stage loading simulations are conducted for a single crystal and polycrystal BCC metal, and the obtained macroscopic results and dislocation substructure evolution are compared qualitatively with the published experimental observations.

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“…The parameters b and G are taken from Frost and Ashby (1982). The value of ρ 0 is presented by Krejci and Lukas (1971). The latent interaction coefficient A αu is identified and the self-interaction coefficient A αα is obtained by assuming a ratio of 1.4 between latent and self-hardening.…”

Section: Reverse Deformationmentioning

confidence: 99%

A composite dislocation cell model to describe strain path change effects in BCC metals

Yalçınkaya¹,

Brekelmans²,

Geers³

2009

Modelling Simul. Mater. Sci. Eng.

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Sheet metal forming processes are within the core of many modern manufacturing technologies, as applied in, e.g., automotive and packaging industries. Initially flat sheet material is forced to transform plastically into a three-dimensional shape through complex loading modes. Deviation from a proportional strain path is associated with hardening or softening of the material due to the induced plastic anisotropy resulting from the prior deformation. The main cause of these transient anisotropic effects at moderate strains is attributed to the evolving underlying dislocation microstructures. In this paper, a composite dislocation cell model, which explicitly describes the dislocation structure evolution, is combined with a BCC crystal plasticity framework to bridge the microstructure evolution and its macroscopic anisotropic effects. Monotonic and multi-stage loading simulations are conducted for a single crystal and polycrystal BCC metal, and the obtained macroscopic results and dislocation substructure evolution are compared qualitatively with the published experimental observations.

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Interface Engineering at the Nanoscale: Synthesis of Low‐Energy Boundaries

Kapp,

Eckert,

Renk

2024

Adv Eng Mater

1

0

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The low toughness and structural stability of nanostructured materials are strongly related to the numerous grain boundaries and interfaces. Among other design stratgies, the use of low‐energy boundaries has turned out to provide the most comprehensive improvement of the property spectrum targeting on ductility, toughness, as well as thermal and microstructural stability upon mechanical loading. Cyclic high‐pressure torsion (CHPT) is one prosperous technique to synthesize low‐angle boundaries (LAGB) at the nanoscale, enabling the production of high‐strength materials. It is presented here with an in‐depth analysis of the structural evolution focusing on the effect of different strain amplitudes and accumulated strains as well as crystal structure to understand how these parameters need to be adjusted to optimize the fraction of LAGBs. Different than expected from classical fatigue testing, the crystal structure seems to play a minor role for the cell structure evolution at comparably large strain amplitudes. It is, therefore, a strong asset that CHPT is feasible to produce nanostructures LAGB boundaries in both FCC and BCC structures. Furthermore, by optimizing the geometry of the anvils, it enables homogenous structural sizes in the entire sample as in contrast to other techniques the strain gradient impact on LAGB formation can be overcome.

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Dislocation substructure in fatigued α-iron single crystals

Cited by 12 publications

References 17 publications

Control of size and density of self-assembled Au droplets via systematic deposition amount control on high-index GaAs type-A surfaces

Control of size and density of self-assembled Au droplets via systematic deposition amount control on high-index GaAs type-A surfaces

A composite dislocation cell model to describe strain path change effects in BCC metals

Interface Engineering at the Nanoscale: Synthesis of Low‐Energy Boundaries

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