Influence of Elastic Anisotropy on the Dislocation Contribution to the Elastic Constants

Koehler, J. S.; deWit, G.

doi:10.1103/physrev.116.1121

Cited by 38 publications

(3 citation statements)

References 6 publications

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“…This could result in relatively smaller value of the bulk Young's modulus compared to the microscopic ones obtained within a small gauge volume illuminated by X-ray beam through the tensile sample. This agrees with Koehler and DeWit classical theory [22,23] (Eq. 5) :…”

Section: Diffraction Elastic Constantssupporting

confidence: 79%

Determination of polycrystal diffraction elastic constants of Ti–2.5Cu by using in situ tensile loading and synchrotron radiation

Maawad

Brokmeier

Zhong

et al. 2014

Materials Science and Engineering: A

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Residual stress determination in engineering components from diffraction strain measurements needs reliable diffraction elastic constants (DECs). From this sense, in situ uniaxial tensile loading experiment was performed on alpha titanium alloy Ti-2.5Cu at the HEMS beamline at DESY by means of a monochromatic synchrotron X-ray diffraction. A comparison between measured (polycrystal) and calculated (single crystal) DECs using for example Kröner model was presented and discussed. The results revealed that the measured DECs slightly differ from the calculated ones. Furthermore, changes in the lattice parameters a and c as well as c/a ratio during tensile loading were also investigated.

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Section: Diffraction Elastic Constantssupporting

confidence: 79%

Determination of polycrystal diffraction elastic constants of Ti–2.5Cu by using in situ tensile loading and synchrotron radiation

Maawad

Brokmeier

Zhong

et al. 2014

Materials Science and Engineering: A

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“…Young's modulus is decreased because reversible dislocation movements cause a reversible elastic expansion contribution to the total elongation. For this reason, the total strain is increased for a given stress, which is associated with a lower elastic stiffness [56]. Furthermore, it has to be taken into account that the cell-like substructure can be considered two separate structural constituents with different material properties due to differences in the respective chemical composition.…”

Section: Influence Of the Built-up Direction And The Slmdevice On The...mentioning

confidence: 99%

Microstructure and mechanical properties of 316L austenitic stainless steel processed by different SLM devices

Röttger

Boes

Theisen

et al. 2020

Int J Adv Manuf Technol

148

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In this work, we examined the influence of different types of selective laser melting (SLM) devices on the microstructure and the associated material properties of austenitic 316L stainless steel. Specimens were built using powder from the same powder batch on four different SLM machines. For the specimen build-up, optimized parameter sets were used, as provided by the manufacturers for each individual SLM machine. The resulting microstructure was investigated by means of scanning electron microscopy, which revealed that the different samples possess similar microstructures. Differences between the microstructures were found in terms of porosity, which significantly influences the material properties. Additionally, the build-up direction of the specimens was found to have a strong influence on the mechanical properties. Thus, the defect density defines the material’s properties so that the ascertained characteristic values were used to determine a Weibull modulus for the corresponding values in dependence on the build-up direction. Based on these findings, characteristic averages of the mechanical properties were determined for the SLM-manufactured samples, which can subsequently be used as reference parameters for designing industrially manufactured components.

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“…where K depends on line direction. For Cu, DeWit and Koehler [24] give an approximately sinusoidal dependency of K on the orientation angle θ with average value = K 59.3 GPa. The shape of the bowed out segment is then an elliptical segment (oblate for screw and prolate for edge orientations).…”

Section: Quasi-elastic Deformation Regimementioning

confidence: 95%

Microplasticity and yielding in crystals with heterogeneous dislocation distribution

Zhang

Xiong

Fan

et al. 2019

Modelling Simul. Mater. Sci. Eng.

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In this study, we use discrete dislocation dynamics (DDD) simulation to investigate the effect of heterogeneous dislocation density on the transition between quasi-elastic deformation and plastic flow in face-centered cubic single crystals. By analyzing the stress-strain curves of samples with an initial, axial dislocation density gradient, we arrive at the following conclusions: (i) in the regime of quasi-elastic deformation before the onset of plastic flow, the effective elastic modulus of the simulated samples falls significantly below the value for a dislocation-free crystal.This modulus reduction increases with decreasing dislocation density gradient: crystals with homogeneous dislocation distribution are thus weakest in the quasi-elastic regime; (ii) the transition towards plastic flow occurs first in regions of reduced dislocation density. Therefore, the overall yield stress decreases with increasing dislocation density gradient; (iii) crystals with dislocation density gradient exhibit a more pronounced hardening stage during which stress is re-distributed onto stronger regions with higher dislocation density until the sample flows at a constant flow stress that is approximately independent on dislocation density gradient. We interpret these findings in terms of a continuum dislocation dynamics inspired model of dislocation density evolution that accounts for inversive dislocation motions. The Manuscript Click here to view linked References 2 transition between quasi-elastic and plastic deformation is interpreted as a transition from inversive to non-inversive dislocation motion, and the initial differences in elastic modulus are related to a density dependent polarizability of the dislocation system. The subsequent plastic flow behavior is analyzed in terms of a modified version of Mughrabi's composite model.

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Influence of Elastic Anisotropy on the Dislocation Contribution to the Elastic Constants

Cited by 38 publications

References 6 publications

Determination of polycrystal diffraction elastic constants of Ti–2.5Cu by using in situ tensile loading and synchrotron radiation

Determination of polycrystal diffraction elastic constants of Ti–2.5Cu by using in situ tensile loading and synchrotron radiation

Microstructure and mechanical properties of 316L austenitic stainless steel processed by different SLM devices

Microplasticity and yielding in crystals with heterogeneous dislocation distribution

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