Results 11 to 20 of about 1,319 (250)

Development of geometrically necessary dislocation density and micromechanical fields in solid state thermal cycle

Journal of Materials Research and Technology
This study presents a comprehensive analysis of time evolution and spatial distribution of crystallographic geometrically necessary dislocation (GND) density induced by solid-state thermal cycling in an IN718 polycrystal.
Anderson Nascimento, Irene J. Beyerlein
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Creep Deformation Estimation of Single Crystal Ni-Based Superalloy by Optimized Geometrically Necessary Dislocation Density Evaluation

Metals
In the framework of high temperature components, the need to evaluate the accumulated creep damage during service life is fundamental to extend the life of components which are currently deemed as scrap as per design intent.
Cristina Motta, Francesco Mastromatteo, Niccolò Baldi, Elisabetta Gariboldi, Luca Bernardini   +4 more
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Quantifying geometrically necessary dislocation density during hot deformation in AA6082 Al alloy [PDF]

Materials Science and Engineering: A, 2021
Physically based constitutive equations incorporating the key microstructural mechanisms e.g. dislocations, grain size, etc, have been used widely to predict the stress-strain behaviour of alloys at plastic and viscoplastic conditions. This enables an accurate prediction of the formed geometry as well as the final underlying microstructures.
Jing-Hua Zheng, Catalin Pruncu, Kai Zhang, Kailun Zheng, Jun Jiang   +4 more
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Role of geometrically necessary dislocation density in multiaxial and non-proportional fatigue crack nucleation [PDF]

International Journal of Fatigue, 2020
Abstract Experimental and crystal plasticity modelling studies have been carried out to investigate non-proportionality and stress state effects in fatigue in a 316 stainless steel and nickel-based superalloy RR1000 which have substantial effects on fatigue life.
Chen, B, Janssens, KGF, Dunne, FPE
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A finite element method to calculate geometrically necessary dislocation density: Accounting for orientation discontinuities in polycrystals

Acta Materialia, 2023
Strain gradients have been used to link various microscale deformation phenomena to the mechanical response of a polycrystalline material, revealing sub-crystal deformation structures. The strain gradients are computed in terms of the orientation gradients and then converted to geometrically necessary dislocation densities, a quantity considered ...
Demir, E, Horton, EW, Kareer, A, Collins, DM, Mostafavi, M, Knowles, D   +5 more
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Evolution of geometrically necessary dislocation density from computational dislocation dynamics

IOP Conference Series: Materials Science and Engineering, 2009
This paper presents a method for calculating GND densities in dislocation dynamics simulations. Evolution of suitably defined averages of GND density as well as maps showing the spatial nonuniform distribution of GNDs are analyzed under uniaxial loading.
P J Guruprasad, A A Benzerga
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Viewpoint: experimental recovery of geometrically necessary dislocation density in polycrystals

Scripta Materialia, 2003
Abstract Application of electron backscattering diffraction methods to recover estimates of the geometrically necessary dislocation density is described. The limitations of the method arising from the opacity of crystalline materials and the spatial and angular resolution limits are discussed.
B.S El-Dasher, B.L Adams, A.D Rollett
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Length-scale effect due to periodic variation of geometrically necessary dislocation densities

International Journal of Plasticity, 2013
Abstract Strain gradient plasticity theories have been successful in predicting qualitative aspects of the length scale effect, most notably the increase in yield strength and hardness as the size of the deforming volume decreases. However new experimental methodologies enabled by recent developments of high spatial resolution diffraction methods in ...
Oeztop, Muin S., Niordson, Christian F., Kysar, Jeffrey W.   +2 more
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Resolving geometrically necessary dislocation density onto individual dislocation types using EBSD-based continuum dislocation microscopy [PDF]

International Journal of Plasticity, 2016
Abstract Modeling of plasticity is often hampered by the difficulty in accurately characterizing dislocation density on the microscale for real samples. It is particularly difficult to resolve measured dislocation content onto individual dislocation types at the length scales most commonly of interest in plasticity studies.
T.J. Ruggles, D.T. Fullwood, J.W. Kysar
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Geometrically necessary dislocation density distributions in Ti–6Al–4V deformed in tension

Acta Materialia, 2011
Abstract We have used cross-correlation-based analysis of electron backscatter diffraction patterns to map lattice rotations in polycrystalline samples of Ti–6Al–4V before and after moderate (6%) tensile deformation. The sensitivity is improved compared to conventional Hough-based indexing and allows the density of geometrically necessary ...
Littlewood, P, Britton, T, Wilkinson, A
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