High strain gradient plasticity associated with wedge indentation into face-centered cubic single crystals: Geometrically necessary dislocation densities

Kysar, Jeffrey W.; Gan, Yong X.; Morse, Timothy L.; Chen, Xi; Jones, Milton E.

doi:10.1016/j.jmps.2006.09.009

Cited by 120 publications

(62 citation statements)

References 30 publications

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“…From Figure 6a, we notice that only regions closest to the indentation impression have sustained large in-plane lattice rotations, and these regions appear to be divided into four zones, with each one of opposite sense to the adjacent zone. We find no large rotation-free areas directly adjacent to the nanoindent impression, as was found in the previous studies [30,31]. A significant rotation difference, about 26 in-plane, is measured on the left side of the indent impression between the two left rotational lobes.…”

Section: Adf Stem Imaging: Dislocation-dislocation Interactionssupporting

confidence: 85%

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Multiscale analysis of nanoindentation-induced defect structures in gum metal

et al. 2018

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Using ex-situ transmission electron microscopy and the recently developed nanoprobe diffraction (NPD) technique, we characterize a nanoindented solution treated gum metal.Lattice rotations are resolved at a 1.2 nanometer length-scale and shown to be continuous within the nanoindentation pit; further, it is shown that these can be accommodated by a reasonable number of geometrically necessary dislocations at a density of ~10^15/m 2 . We additionally provide direct evidence that dislocations within the nanoindent, rather than secondary phase nanoparticles, can serve as potent barriers to dislocation motion. We also demonstrate that plasticity in these alloys under nanoindentation can be accommodated solely by dislocation nucleation and propagation, with no competing deformation mechanisms present. Conventional transmission electron microscopy and "gb" analysis reveal the presence of dislocations on <-111>{110} slip systems and highly localized plastic deformation in the form of shear bands on <111>{-1-12} slip systems, similar to previously observed "giant faults". Keyword

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Section: Adf Stem Imaging: Dislocation-dislocation Interactionssupporting

confidence: 85%

“…Table 2 presents a summary of these studies (Refs. [30,31,44,45]) along with the current investigation. It is noted that there is no readily available prior study for BCC materials and comparison is made with FCC materials.…”

Section: Nanoindentation-induced Lattice Rotationsmentioning

confidence: 89%

Multiscale analysis of nanoindentation-induced defect structures in gum metal

et al. 2018

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“…This therefore provides an underdetermined problem, with fewer constraints than potential dislocation types for which we want to determine densities. There are many routes discussed in the literature to treat this problem (Britton et al, 2009;Gardner et al, 2010;Kysar et al, 2010;Kysar et al, 2007;Sun et al, 2000) (Arsenlis and Parks, 1999;Field et al, 2010;Hardin et al, 2011;Hardin et al, 2013;Ruggles and Fullwood, 2013) (Demir et al, 2009), with varying degrees of success and merit. We choose to select a solution that physically supports the curvature measured and also minimises the total line energy, accounting for differences between screw and edges using isotropic elastic energies, of the dislocations used (this a L 1 minimisation scheme).…”

Section: Hr-ebsd and Gnd Densitymentioning

confidence: 99%

The orientation and strain dependence of dislocation structure evolution in monotonically deformed polycrystalline copper

Jiang

Britton

Wilkinson

2015

International Journal of Plasticity

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“…The GN dislocation density can be easily measured by EBSD (Calcagnotto et al, 2010;Moussa et al, 2015;Wright et al, 2015). Numerous studies have measured the GN dislocation density of indentation (Kysar et al, 2007;Demir et al, 2009;Rester et al, 2007). Demir et al (2009) performed indentation tests of a Ni(111) single crystal and measured GN dislocation.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the indentation size effect based on measurement of the geometrically necessary dislocation density by electron backscatter diffraction

Hasunuma

Miyazaki

Shimada

et al. 2018

Mechanical Engineering Journal

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In this study, we investigated the mechanism of the indentation size effect based on measurement of the geometrically necessary (GN) dislocation density. The GN dislocation density was measured around impressions by electron backscatter diffraction (EBSD). Indentation tests were performed for two types of single crystal Ni with different crystal orientations: (001) and (111). Difference between (111) and (001) orientation are small in the relationship of the hardness and the penetration depth. However, the deformation behavior and distribution of the GN dislocation density are different for the (001) and (111) orientations. For the (111) orientation, the GN dislocation density increases with decreasing hardness. However, the GN dislocation density for the (001) orientation increases with increasing hardness. The mechanism of the indentation size effect for the (001) orientation can be attributed to the increase of the GN dislocation density. In addition, we investigated the effect of the indenter shape on the indentation size effect. Indentation tests were performed with different apex angles. The hardness using an indenter with a large apex angle is smaller than that using an indenter with a small apex angle. The GN dislocation density increases with decreasing apex angle. The mechanism of the indentation size effect for the apex angle can be attributed to the increase of the GN dislocation density. We prepared another indenter with a dull tip. The hardness using the dull indenter is larger than that using the sharp indenter. The GN dislocation density distribution changes with the indenter sharpness but the GN dislocation density is similar. For the dull indenter, variation of the GN dislocation density has a smaller effect on the indentation size effect than the increase of the resistance because of the different indenter shape.

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High strain gradient plasticity associated with wedge indentation into face-centered cubic single crystals: Geometrically necessary dislocation densities

Cited by 120 publications

References 30 publications

Multiscale analysis of nanoindentation-induced defect structures in gum metal

Multiscale analysis of nanoindentation-induced defect structures in gum metal

The orientation and strain dependence of dislocation structure evolution in monotonically deformed polycrystalline copper

Investigation of the indentation size effect based on measurement of the geometrically necessary dislocation density by electron backscatter diffraction

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