Quantification of internal dislocation density using scanning transmission electron microscopy in ultrafine grained pure aluminium fabricated by severe plastic deformation

Miyajima, Yoji; Mitsuhara, Masatoshi; Hata, Satoshi; Nakashima, Hideharu; Tsuji, Nobuhiro

doi:10.1016/j.msea.2010.09.058

Cited by 84 publications

(25 citation statements)

References 13 publications

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“…Fig. 12 shows the predicted evolution of average dislocation density,  ig , for the alloys considered in the present work, together with data on dislocation densities for selected Al alloys obtained from the literature [49,50,81,82]. Fig.…”

Section: Structure Of Lagbs and Hagbs And Dislocation Densitiesmentioning

confidence: 99%

A model of grain refinement and strengthening of Al alloys due to cold severe plastic deformation

Qiao

Gao

Starink

2012

Philosophical Magazine

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This paper presents a model which quantitatively predicts grain refinement and strength/hardness of Al alloys after very high levels of cold deformation through processes including cold rolling, equal channel angular pressing (ECAP), multiple forging (MF), accumulative rolling bonding (ARB) and embossing. The model deals with materials in which plastic deformation is exclusively due to dislocation movement, which is in good approximation the case for aluminium alloys. In the early stages of deformation, the generated dislocations are stored in grains and contribute to overall strength. With increase in strain, excess dislocations form and/or move to new cell walls/grain boundaries and grains are refined. We examine this model using both our own data as well as the data in the literature. It is shown that grain size and strength/hardness are predicted to a good accuracy.

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Section: Structure Of Lagbs and Hagbs And Dislocation Densitiesmentioning

confidence: 99%

A model of grain refinement and strengthening of Al alloys due to cold severe plastic deformation

Qiao

Gao

Starink

2012

Philosophical Magazine

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“…57) Grain re nement by SPD processing accompanies other microstructural changes in a complicated way. These change includes phase transformation, 58,59) redistribution of impurity and solute elements, 60,61) the morphology change of precipitation by partial dissolution and physical fragmentation, [62][63][64][65] residual dislocation density, 66,67) texture, [68][69][70][71] etc. Effect of these changes is superimposed on grain size effect on corrosion, and this may cloud the underlying law dominating grain-size-dependency, if any, generic to SPD.…”

Section: Introductionmentioning

confidence: 99%

Corrosion of Ultrafine Grained Materials by Severe Plastic Deformation, an Overview

Miyamoto

2016

Mater. Trans.

114

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Corrosion of ultra ne grain (UFG) materials by severe plastic deformation (SPD) is reviewed in light of the existing literature and microstructural change. Fortunately, by holistic survey of the literature, it seems likely that grain re nement by SPD, while enhancing mechanical properties, does not compromise the overall corrosion resistance, and in many case, improve it in comparison with coarse-grained counterparts, although there are some contradictory results within the same materials and same environment. The degree of impact of UFG formation on corrosion is highest in stainless steels followed by aluminum and magnesium alloys whereas it is relatively marginal in pure copper and titanium. The effect of UFG formation by SPD on corrosion is imparted by not only grain re nement, but also other microstructural change occurring commonly in SPD in general and unique to each speci c SPD method. In this review, an attention is paid speci cally to the former case, and this includes shuf ing or redistribution of chemical inhomogeneity into a ner scale, deformation-induced grain boundaries and high internal stress stemming from these grain boundaries. The literature on stress corrosion cracking (SCC) of UFG materials are de nitely insuf cient to nd the general trends, more studies are waited.

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“…For Al and SiC, the thermal expansion ratio is 10: after HPT [6] and ECAP [6] processing respectively. Miyajima et al [7] found that the residual dislocation density was around 10 In the current study, Al/Ti/Al laminates underwent severe plastic deformation during rolling, causing dislocations that were annihilated during annealing at the first stage. Figure 1b shows low residual dislocation density and some voids in the pure aluminium zone.…”

Section: Resultsmentioning

confidence: 48%

“…Based on the theory, some Severe Plastic Deformation (SPD) techniques have been developed to produce * hailiang@uow.edu.au or yuhailiang1980@tom.com nanostructured metals [2-5]. After an SPD processing, the residual dislocation density in metals is generally higher than that before processing [6,7], however, further increase in the strain can lead to grain coarsening and dislocation annihilation [8].…”

Section: Introductionmentioning

confidence: 99%

Abnormally high residual dislocation density in pure aluminum after Al/Ti/Al laminate annealing for seven days

Lü

Kong

2014

Philosophical Magazine Letters

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. (2014). Abnormally high residual dislocation density in pure aluminum after Al/Ti/Al laminate annealing for seven days. Philosophical Magazine Letters: structure and properties of condensed matter, 94 (11), 732-740.Abnormally high residual dislocation density in pure aluminum after Al/ Ti/Al laminate annealing for seven days AbstractWe report an abnormally high residual dislocation density in aluminium in an Al/Ti/Al laminate annealed at 873 K for seven days. The residual dislocation density reaches 7.5 x 1014 m−2, higher than that in aluminum after severe plastic deformation processes such as accumulative roll bonding and high-pressure torsion. It is proposed that the high residual dislocation density may result from obstruction of the movement of TiAl3 nanoparticles by the grain boundary and Ti atoms conglomerating at vacancies distributed in the aluminium matrix at a high temperature for a sufficient time to allow a relatively stable crystal.

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Quantification of internal dislocation density using scanning transmission electron microscopy in ultrafine grained pure aluminium fabricated by severe plastic deformation

Cited by 84 publications

References 13 publications

A model of grain refinement and strengthening of Al alloys due to cold severe plastic deformation

A model of grain refinement and strengthening of Al alloys due to cold severe plastic deformation

Corrosion of Ultrafine Grained Materials by Severe Plastic Deformation, an Overview

Abnormally high residual dislocation density in pure aluminum after Al/Ti/Al laminate annealing for seven days

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