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

Jiang, Jun; Britton, T. Ben; Wilkinson, Angus J.

doi:10.1016/j.ijplas.2015.02.005

Cited by 93 publications

(34 citation statements)

References 45 publications

(66 reference statements)

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“…A closer inspection on the GND maps and combining them with IPF maps especially for the 2 cycles and 200 cycles, it can be seen that the grains with <111> orientation with respect to the applied macro stress (in blue on the IPF map) tend to have relatively low GND density and regular dislocation cell structures, more irregular dislocation bands with significantly higher densities are formed in other grains. This agrees well with our more quantitative observations of much larger HR-EBSD maps of dislocation structures formed in monotonically deformed copper [45] Evolution with increasing number of cycles of GND formed dislocation structure is not very strong however there does seem to be more dislocation bands of raised GND density in the 200 and 2000 cycle samples. A comparison between cyclic deformation and tensile deformation does not show obvious differences in the structure and density of stored GNDs.…”

Section: Maps Of Microstructure Gnd Density and Residual Stressessupporting

confidence: 91%

“…Orientation dependence of dislocation structure has been reported in the extensive TEM studies by Huang & Winther [56,57] for monotonic deformation in rolling and tension to larger strains than examined here. Recent HR-EBSD studies of GND structure formed in monotonically deformed copper seem to be in broad agreement and found that <011> and <001> oriented grains have more boundary-liked dislocation structure and more regular dislocation cell structure is preferentially formed in <111> oriented grains [45]. Gaudin and Feaugas [58]used TEM to document in detail the orientation dependence of dislocation structures found in 316L stainless steel after tension-tension fatigue.…”

Section: Discussionmentioning

confidence: 81%

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Evolution of intragranular stresses and dislocation densities during cyclic deformation of polycrystalline copper

2015

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We have used the cross-correlation based high resolution electron backscattering diffraction (HR-EBSD) technique to evaluate at high spatial resolution the spatial patterning of the type III intragranular residual stresses and geometrically necessary dislocation (GND) density within polycrystalline Cu after cyclic deformation. Oxygen free high conductivity (OFHC) polycrystalline copper samples were cyclically deformed under stress-control at a load ratio of 0.1 and EBSD measurements were made at points throughout the early stages of fatigue when strain amplitudes and cyclic creep rates are changing most significantly, namely at 0 cycles, 2 cycles, 200 cycles and 2000 cycles. Statistical analysis is presented showing that moderate correlations exist between stored GND density, residual intragranular stress and distance from the nearest grain boundaries or/and triple junctions. Ref: Ms.No.A-15-232Manuscript: "Evolution of intragranular stresses and dislocation densities during cyclic deformation of polycrystalline copper" Dear Prof MahajanWe are very pleased to submit our revised manuscript to Acta Materialia for considering publication. Each of referee's comment and suggestion has been carefully addressed. Detailed explanations are included in the 'Response to Reviewer' file. All changes and corrections to our original manuscript have been highlighted in the revised manuscript.We would be very grateful for Editor's effort and time to process our manuscript and very look forward to hearing from you soon. Authors are very grateful to Reviewer's time, effort and constructive comments. In order to comprehensively revise our manuscript and give most appropriate response, we address Reviewer's comments one by one in detail in the following section. (Reviewer's comments are marked using red colour, correction to the manuscript are marked as yellow and Authors responses are marked as blue.Editor's/Reviewer's comments: This paper gives some interesting insights into dislocation and stress development during cyclic testing. Overall the analysis is appropriate, although I was surprised about two things: the correlations reported in the paper are pretty low; I was surprised that the authors did not pursue this a little further to factor out some of the issues (such as substructure development) that appear to play an important role in causing this. Relating to the previous point, the authors mention dislocation substructure development in an extremely cursory and handwaving fashion. They mention correlations with orientation and different types of structure, but in an almost off-handed way that does not even connect with the wealth of literature on the subject. Issue 2. should certainly be fixed, and it would be nice to improve issue 1. a little if possible. I have made comments on the manuscript that I hope will be helpful (including pointing out a few typos).1. These coefficients are low. The correlation coefficients are generally not very high (~-0.2) (That's a bit of a stretch) This is a sensible suggestion and ...

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Section: Maps Of Microstructure Gnd Density and Residual Stressessupporting

confidence: 91%

Section: Discussionmentioning

confidence: 81%

Evolution of intragranular stresses and dislocation densities during cyclic deformation of polycrystalline copper

2015

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“…Generally GND density hot spots tend to form bands which can link across several grains and accumulate around triple junctions and the tips of twin boundaries. Compared to monotonic and cyclic loading in copper in Jiang et al [31,51,57], very similar dislocation networks and hot spot accumulation trends are formed in the cyclically deformed nickel. The form and structure of the bands here follow a 45 degree angle to the macroscopic stress axis and coincide with the inclusion.…”

Section: Discussionmentioning

confidence: 83%

On the mechanistic basis of fatigue crack nucleation in Ni superalloy containing inclusions using high resolution electron backscatter diffraction

et al. 2015

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This is an authors' copy of a manuscript published in Acta Materialia Volume 97, 15 September 2015, Pages 367-379. http://dx.doi.org/10.1016/j.actamat.2015.06.035 AbstractA series of interrupted three-point bend low-cycle fatigue tests were carried out on a powder metallurgy FHG96 nickel superalloy sample containing non-metallic inclusions. High resolution electron backscatter diffraction (HR-EBSD) was used to characterize the distribution and evolution of geometrically necessary dislocation (GND) density, residual stress and total dislocation density near a non-metallic inclusion. A systematic study of room temperature cyclic deformation is presented in which slip localisation, cyclic hardening, ratcheting and stabilisation occur, through to crack formation and microstructurally-sensitive propagation. Particular focus is brought to bear at the inclusion-matrix interface. Complex inhomogeneous deformation structures were directly observed from the first few loading cycles, and these structures were found not to vary significantly with increasing number of cycles. A clear link was observed between crack nucleation site and microstructurally-sensitive growth path and the spatially-resolved sites of extreme values of residual stress and GND density.

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“…However, strain localization does not necessarily occur in regions near grain boundaries or triple junctions. HR-EBSD analysis in polycrystalline copper has demonstrated that patterns of GNDs are orientation dependent, regardless of proximity to grain boundaries [40]. Grains with different orientations exhibit distinct dislocation structures and therefore this can have an influence on strain distribution.…”

Section: Discussionmentioning

confidence: 99%

Slip localization and fatigue crack nucleation near a non-metallic inclusion in polycrystalline nickel-based superalloy

Zhang

Jiang

Shollock

et al. 2015

Materials Science and Engineering: A

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Fatigue crack nucleation at a non-metallic agglomerate inclusion has been studied by high spatial resolution Digital Image Correlation (HR-DIC) and high angular resolution Electron Backscatter Diffraction (HR-EBSD). Spatial and temporal characterization and correlation of deformation with underlying microstructures has been performed, with distributions of plastic strain measured from HR-DIC; and residual stress and density of geometrically necessary dislocations (GND) measured from HR-EBSD. Initial residual stress and GND fields, as a consequence of differing thermal expansivities in the metallic and oxide phases, localized around the agglomerate have been quantified using HR-EBSD. The localization of the pre-existing stress and dislocation states appear to lead to early onset of plasticity upon subsequent mechanical loading. Heterogeneous distributions of plastic strain have been observed in the course of the fatigue test by HR-DIC. Crack nucleation via agglomerate/nickel interface decohesion and particle fracture has been demonstrated and this is correlated with the elevation in strain and dislocation density. The measurements of residual stress, strain, and dislocation density provide key information for the mechanisms of fatigue cracking and the development of damage nucleation criteria in these material systems.2

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

Cited by 93 publications

References 45 publications

Evolution of intragranular stresses and dislocation densities during cyclic deformation of polycrystalline copper

Evolution of intragranular stresses and dislocation densities during cyclic deformation of polycrystalline copper

On the mechanistic basis of fatigue crack nucleation in Ni superalloy containing inclusions using high resolution electron backscatter diffraction

Slip localization and fatigue crack nucleation near a non-metallic inclusion in polycrystalline nickel-based superalloy

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