Einfluß der Stapelfehlerenergie auf den kristallographischen Umgitterungsmechanismus der γ/α‐Umwandlung in hochlegierten Stählen

Schümann, H. J.

doi:10.1002/crat.19740091009

Cited by 70 publications

(44 citation statements)

References 15 publications

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“…However, in other grains, where the islands were much larger, they were identified as α'-martensite via EBSD [89]. This is in very good agreement with [90] showing a direct phase transition from the austenite (fcc) to martensite (bcc). Figure 10(c) shows the planar arrangement of individual dislocations along two different slip systems.…”

Section: Planar Dislocation Arrangement and Martensitic Phase Transfosupporting

confidence: 76%

Case studies on the application of high-resolution electron channelling contrast imaging – investigation of defects and defect arrangements in metallic materials

Weidner

Biermann

2015

Philosophical Magazine

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In 1967, Coates discovered the electron channelling contrast of backscattered electrons (BSEs) in scanning electron microscopy, and by this the possibility to investigate arrangements of lattice defects in deformed microstructures of materials. Since that time, a straightforward development of the scanning electron microscopes as well as of the electron channelling contrast technique took place. Nowadays, the performance of scanning electron microscopes is high enough that the resolution of electron channelling contrast imaging (ECCI) micrographs is comparable with conventional bright field transmission electron microscopy (TEM) micrographs. In the first part of the present paper, a historical review on the development of the ECCI technique starting from its discovery more than 45 years ago up to the combination with other advanced methods of scanning electron microscopy like electron backscatter diffraction or high-resolution selected area channelling patterning in the last few years is given. Major important investigations using this technique for the visualization of individual lattice defects like stacking faults (SFs) and dislocations or dislocation arrangements are chronologically summarized. The second part demonstrates that nowadays, ECCI micrographs taken in high-resolution scanning electron microscopes can be called high-resolution ECCI (HR-ECCI). It is shown that the resolution of individual SFs and dislocations in the HR-ECCI micrographs is comparable to that of conventional TEM (about 15 nm defect image width). Furthermore, the paper is demonstrating that HR-ECCI micrographs can be obtained for various types of materials after different mechanical loadings and different grain sizes ranging from large grain size of 500 μm (cast steel) down to less than 2 μm (γ-TiAl).

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Section: Planar Dislocation Arrangement and Martensitic Phase Transfosupporting

confidence: 76%

Case studies on the application of high-resolution electron channelling contrast imaging – investigation of defects and defect arrangements in metallic materials

Weidner

Biermann

2015

Philosophical Magazine

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“…It has been known for a long time that highmanganese steels are plastically deformed through strain-induced martensite formation, mechanical twinning, and, finally, pure dislocation glide, due to increases in the SFE value. [1][2][3][4][5][6][7][8][9][10][11] The SFE of these steel grades increases intensively as a result of increases in the carbon [12] and aluminum [13,14] contents as well as the temperature, [15,16] while it decreases as a result of increases in the austenite grain size. [17,18] The effect of manganese (>15 wt pct) on increases in the SFE has been debated in several research articles.…”

Section: Introductionmentioning

confidence: 99%

Derivation and Variation in Composition-Dependent Stacking Fault Energy Maps Based on Subregular Solution Model in High-Manganese Steels

Saeed-Akbari

Imlau

Prahl

et al. 2009

Metall Mater Trans A

618

272

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A subregular solution thermodynamic model was used to calculate the stacking fault energies (SFEs) of high-manganese (10 to 35 wt pct) steels with carbon contents of 0 to 1.2 wt pct. Based on these calculations, composition-dependent diagrams were developed showing the regions of different SFE values for the mentioned composition range. These diagrams were called SFE maps. In addition, variations in the SFE maps were observed through increasing the temperature, aluminum content, and austenite grain size. These changes were seen either as an increasing trend of SFE caused by raising the temperature and aluminum content, or as a decreasing behavior caused by increasing the grain size. The SFE value of 20 mJ/m 2 within these diagrams was introduced as the upper limit for the strain-induced martensite formation. The variations in this limit caused by increasing the temperature and aluminum content were mathematically evaluated to find out the minimum amount of manganese that was required to avoid the martensitic transformation. By introducing the isocarbon and isomanganese diagrams of the SFE, it was seen that both temperature and aluminum had a greater effect on the SFE when added to the steels with the lower manganese contents. Moreover, by adding more aluminum to the composition of the high-manganese steels, its influence on the SFE decreased continuously.

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“…3 Calculated (a) self-diffusivity of bcc Fe in comparison with experimental data [30] and (b) grain boundary diffusivity on some grain boundaries in bcc Fe Fig. 4 Effect of Mn on the intrinsic stacking fault energy of fcc Fe (a) by the present MEAM calculation, [8] and (b) by experiments [32,33] or thermodynamic calculation. [34] The stacking fault energy of pure Fe is set to be zero in (a)…”

Section: Computation Of Stacking Fault Energymentioning

confidence: 97%

“…According to the present calculation, the stacking fault energy of fcc Fe decreases up to about 5 at.% Mn and then increases with increasing Mn content. Figure 4(b) shows the effect of Mn on the stacking fault energy in various austenitic steels obtained from experiments [32,33] or a thermodynamic calculation. [34] Even though there are differences in the absolute values between the present calculation and literature data and also among the literature data sets, all results show a qualitative agreement in that the stacking fault energy initially decreases with Mn addition and then increases with further addition of Mn.…”

Section: Computation Of Stacking Fault Energymentioning

confidence: 99%

A Semi-Empirical Atomistic Approach in Materials Research

Lee

2009

J. Phase Equilib. Diffus.

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With developments of semi-empirical interatomic potentials for realistic materials systems, atomistic approaches to a wide range of bulk and nanostructured materials become more and more feasible. This article outlines a recently developed semi-empirical interatomic potential model, the second nearest-neighbor modified embedded-atom method that shows a strong applicability to multicomponent systems. It is shown that the interatomic potentials can well reproduce fundamental physical properties of representative materials systems. Examples are used to illustrate the applications of the atomistic approach to calculation of fundamental physical properties of both nano and bulk structural materials such as thermodynamic, elastic, interface, and defect properties necessary to understand the materials behavior and to serve as input to larger-scale simulations.

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Einfluß der Stapelfehlerenergie auf den kristallographischen Umgitterungsmechanismus der γ/α‐Umwandlung in hochlegierten Stählen

Cited by 70 publications

References 15 publications

Case studies on the application of high-resolution electron channelling contrast imaging – investigation of defects and defect arrangements in metallic materials

Case studies on the application of high-resolution electron channelling contrast imaging – investigation of defects and defect arrangements in metallic materials

Derivation and Variation in Composition-Dependent Stacking Fault Energy Maps Based on Subregular Solution Model in High-Manganese Steels

A Semi-Empirical Atomistic Approach in Materials Research

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