Dislocation structures in cyclically deformed [001] copper crystals

Jin, N.Y.; Winter, A. T.

doi:10.1016/0001-6160(84)90123-8

Cited by 96 publications

(20 citation statements)

References 7 publications

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“…This kind of dislocation structure is similar to the ladder structure found in copper single and poly crystals, which is formed by the activation of only a primary slip system, 7,16,17) but at the same time it may be called a labyrinth structure, which is formed by the activation of more than two slip systems as reported in Fe-3%Si 14) alloy, Fe-25%Cr 18) alloy and Cu. [19][20][21] The dislocation structure shown in Fig. 10, for instance, may be called a labyrinth structure, in the sense that the mixed dislocation structures consisting of periodically arranged dislocation walls and cell structures are observed, which is very similar to the dislocation structures in copper, which have been identified as a labyrinth structure.…”

Section: Evolution Of Dislocation Structure During Fatiguementioning

confidence: 88%

“…10, for instance, may be called a labyrinth structure, in the sense that the mixed dislocation structures consisting of periodically arranged dislocation walls and cell structures are observed, which is very similar to the dislocation structures in copper, which have been identified as a labyrinth structure. 17,19,21) Furthermore, the dislocation structure shown in Fig. 13 may be recognized to be comprised of dislocation walls perpendicular to each other, which are frequently observed in the labyrinth structure in Cu.…”

Section: Evolution Of Dislocation Structure During Fatiguementioning

confidence: 91%

“…13 may be recognized to be comprised of dislocation walls perpendicular to each other, which are frequently observed in the labyrinth structure in Cu. 17,20,21) Turenne et al 22) proposed a theoretical model on the formation mechanism of a labyrinth structure, namely a geometrical model of dipolar dislocation structures based on the stacking of dipole loops, and verified that the labyrinth walls in bcc Fe-25Cr correspond to a pair of {011} walls. The present study has not clarified the crystallographic relationship between a slip system and a dislocation wall, which is necessary in order to identify the dislocation structure and to elucidate its formation mechanism.…”

Section: Evolution Of Dislocation Structure During Fatiguementioning

confidence: 99%

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Evolution of Dislocation Structure and Fatigue Crack Behavior in Fe–Si Alloys during Cyclic Bending Test

et al. 2009

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Fig. 14. TEM micrographs of Ti-IF3(1 % Si) tested under a high stress amplitude showing development of the periodically arranged dislocation wall structure near the top surface (sϭ380.9 MPa, Nϭ8 500).proximately 0.5 mm in the Si-bearing steels. Concerning the interaction between dislocations and grain boundaries during the cyclic test, detailed studies on Cu polycrystal, 17,23) Cu bicrystal 24) and Al polycrystal 25) were carried out taking into account the grain boundary characteristics. Winter et al. 17) and Luoh et al. 23) reported that dislocation free zones (DFZ) along grain boundaries were formed when the vein structures developed within grains, whereas DFZ were not formed in the case of cell structures, which is very similar to the results of the present study using Fe-Si alloy. Although further study is required, Luoh et al. 23) concluded that the multipolar dislocation loop patches (MLPs) and walls (MLWs) are built up due to grain boundary incompatible stresses providing secondary glides, which are thought to cause annihilation of dipole loops by intersecting MLPs or MLWs. Referring to this model, it is inferred that in the Si-bearing steels the difficulty of cross slip leads to the annihilation of dislocation dipole loops in the vicinity of grain boundaries by intersecting MLPs and MLWs, or dislocations simply sinks into grain boundaries. In the case of pure iron after the deformation of cold rolling, localized softening near the initial grain boundaries has been reported. 26)Further systematic quantitative study in bcc metals is necessary to clearly understand the mechanism.The present study shows that the saturated dislocation structure varies with the cyclic stress amplitude. As shown in Fig. 17, the cell width and vein width varied with the ISIJ International, Vol. 49 (2009) stress amplitude, respectively. More specifically, the cell width remained comparatively large, although varying from approximately 5 to 8 mm under low to middle-stress amplitude, and clear cell structures developed under high-stress amplitude with comparatively homogenous and fine cell sizes of 2 to 3 mm. On the other hand, the vein width varied largely under low-stress amplitude, bundled dislocations started to appear under middle-stress amplitude, and the vein width converged to 0.5 to 1 mm dimension homogeneously with further increasing stress amplitude with a channel width of about 0.5 mm. The relationship between the development of dislocation structures and stress amplitude during cyclic deformation has already been investigated from both experimental and theoretical points of view mainly on Cu. 27,28) The cyclic stress (t) of materials with periodically arranged dislocation walls is expressed by the sum of the stress necessary for dislocation to bow out into the channel (t bowing ) and interaction stress (t dip ) of screw dislocation dipoles within the channel. t bowing is expressed by Gb/d c andt dip is by Gb/4ph, where G, b, d c and h are shear modulus, Burgers vector, channel width and interval of slip plane...

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Section: Evolution Of Dislocation Structure During Fatiguementioning

confidence: 88%

Section: Evolution Of Dislocation Structure During Fatiguementioning

confidence: 91%

Section: Evolution Of Dislocation Structure During Fatiguementioning

confidence: 99%

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Evolution of Dislocation Structure and Fatigue Crack Behavior in Fe–Si Alloys during Cyclic Bending Test

et al. 2009

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“…Complex subgrain dislocation patterns in plastically deformed metallic crystals have been observed by many authors [1][2][3][4][5], and these dislocation microstructures are known to affect greatly several aspects of plastic behaviour, such as work hardening, and the Bauschinger and Hall-Petch effects. Currently, attempts at modelling such behaviour are often phenomenological, which leads to significant problems for specimens on the micrometre scale [6,7].…”

Section: Introductionmentioning

confidence: 97%

Relaxation of the single-slip condition in strain-gradient plasticity

Anguige

Dondl

2014

Proc. R. Soc. A.

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We consider the variational formulation of both geometrically linear and geometrically nonlinear elasto-plasticity subject to a class of hard singleslip conditions. Such side conditions typically render the associated boundary-value problems non-convex. We show that, for a large class of non-smooth plastic distortions, a given single-slip condition (specification of Burgers vectors) can be relaxed by introducing a microstructure through a two-stage process of mollification and lamination. The relaxed model can be thought of as an aid to simulating macroscopic plastic behaviour without the need to resolve arbitrarily fine spatial scales.

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“…In [OR99], there is already a number of experimental studies referenced in order to link such kinematically compatible laminates to observed plastic microstructure in a more rigorous manner [RP80,JW84]. Many of these experiments, however, were performed in fatigue, i.e., using repeated oscillating small amplitude plastic deformation.…”

Section: Introductionmentioning

confidence: 99%

Microstructure in Plasticity, a Comparison between Theory and Experiment

Dmitrieva

Raabe

Müller³

et al. 2015

Analysis and Computation of Microstructure in Finite Plasticity

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Abstract. We review aspects of pattern formation in plastically deformed single crystals, in particular as described in the investigation of a copper single crystal shear experiment in [DDMR09]. In this experiment, the specimen showed a band-like microstructure consisting of alternating crystal orientations. Such a formation of microstructure is often linked to a lack of convexity in the free energy describing the system. The specific parameters of the observed bands, namely the relative crystal orientation as well as the normal direction of the band layering, are thus compared to the predictions of the theory of kinematically compatible microstructure oscillating between low-energy states of the non-convex energy. We conclude that this theory is suitable to describe the experimentally observed band-like structure. Furthermore, we link these findings to the models used in studies of relaxation and evolution of microstructure.

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Dislocation structures in cyclically deformed [001] copper crystals

Cited by 96 publications

References 7 publications

Evolution of Dislocation Structure and Fatigue Crack Behavior in Fe–Si Alloys during Cyclic Bending Test

Evolution of Dislocation Structure and Fatigue Crack Behavior in Fe–Si Alloys during Cyclic Bending Test

Relaxation of the single-slip condition in strain-gradient plasticity

Microstructure in Plasticity, a Comparison between Theory and Experiment

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