The influence of point-defect clusters on fatigue hardening of copper single crystals

Piqueras, J.; Grosskreutz, J. C.; Frank, W.

doi:10.1002/pssa.2210110220

Cited by 77 publications

(13 citation statements)

References 29 publications

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“…At first, there appears to be two types of defects within the channels: dipoles, just as in the veins, but there also appears to be dotlike features that others have observed. [35,36,37] Some attribute these to vacancy loops resulting from a large number of point defects generated during deformation, while others [35,38] attributed these to tiny dipoles. Our weak beam and careful tilting experiments agree with the latter investigators.…”

Section: Resultsmentioning

confidence: 98%

Microstructure and mechanisms of cyclic deformation of aluminum single crystals at 77 K

Kassner

Wall²,

Delos-Reyes

1997

Metall Mater Trans A

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Aluminum single crystals were cyclically deformed in single slip at small strain amplitudes at 77 K to presaturation. The observed mechanical behavior is consistent with recent work by other investigators. The dislocation substructure can be described as consisting of dense bundles or veins of edge dislocation dipoles, of a single Burgers vector, separated by lower dislocation density regions or channels where substantial debris is evident. This debris was determined as almost exclusively relatively short edge-dipole segments. Screw dislocations with the same Burgers vector span the channels. In situ cyclic reverse (shear) deformation experiments in the high-voltage transmission electron microscope (HVEM) were successfully performed using the X-Y technique where thin foils are stressed in alternating perpendicular directions. Our experiments indicate that loops frequently expand from the dipole bundles into the channel and the edge component is absorbed by nearby bundles, leaving screw segments behind. The screw dislocations that span the channel move easily and reverse direction with shear reversal. Screws may move first with a strain reversal. A comparable fraction of the strain during each cycle appears to be provided by screw and edge dislocations. Dipole ''flipping'' was not observed. There is no obvious evidence for internal backstresses that assist plastic deformation on reversal of the applied shear.

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Section: Resultsmentioning

confidence: 98%

Microstructure and mechanisms of cyclic deformation of aluminum single crystals at 77 K

Kassner

Wall²,

Delos-Reyes

1997

Metall Mater Trans A

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“…Vacancies can be produced during cyclic deformation by the annihilation of narrow edge dislocation dipoles as well as intersections of dislocations [18,19]. The aggregation of vacancies creates vacancy clusters [20,21] and micropores [18,[22][23][24] in fatigued f.c.c. metals, which are responsible for a volume increase called extrusion [25,26].…”

Section: Fatigue Damage Formation and Annihilation In Metallic Bulk Amentioning

confidence: 99%

Effects of bending fatigue on the electrical resistance in metallic films on flexible substrates

Lee

et al. 2010

Met. Mater. Int.

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The increase of electrical resistance during the strain-controlled bending fatigue of 2 µm-thick inkjet-printed or vacuum deposited metallic films (Cu, Ag) on flexible substrates (BT: Bismaleimide Triazine, PI: Polyimide) was investigated. Electrical resistance increased with an increase in the number of fatigue cycles. The rate of increase in the electrical resistance of inkjet-printed Cu films was lower than that of thermally evaporated films. This phenomenon is attributable to the porous microstructure of inkjet-printed Cu films. The porous structure contains a lot of free volume and a large area of free surface, which can be a sinking site for vacancies formed during the cyclic deformation. It was confirmed that a smaller grain size leads to a lower rate of increase in the electrical resistance, which was ascribed to the easy vacancy annihilation due to a short diffusion length of the vacancy to the grain boundary which is a vacancy sinking site. The rate of increase in the electrical resistance was also influenced by the grain boundary geometry. The lower rate of the evaporated Ag film on a BT substrate was attributed to the crack-like grain boundaries, which were expected to behave like pores.

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“…Contrast phenomena in TEM investigations on fatigued copper single crystals have been interpreted as vacancy clusters with a diameter of up to 4 nm by Piqueras et al 43 and others. 23,44 Grobstein et al 55 performed measurements of electrical resistivity and positron annihilation during fatigue of nickel.…”

Section: E Positron Traps and Trapping Modelsmentioning

confidence: 94%

Nondestructive monitoring of fatigue damage evolution in austenitic stainless steel by positron-lifetime measurements

Holzwarth

Schaaff

2004

Phys. Rev. B

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Positron-lifetime measurements have been performed on austenitic stainless steel during ͑i͒ stress-and ͑ii͒ strain-controlled fatigue experiments for different applied stress and strain amplitudes, respectively. For this purpose a generator-detector assembly with a 72 Se/ 72 As positron generator ͓maximum activity 25 Ci ͑0.9 MBq͔͒ has been mounted on mechanical testing machines in order to measure the positron lifetime without removing the specimens from the load train. The average positron lifetime has been determined by a ␤ ϩ Ϫ␥ coincidence. The feasibility to use the average positron lifetime for monitoring the evolution of fatigue damage and to predict early failure has been examined. In strain-and stress-controlled experiments the average positron lifetime shows a pronounced increase within the first 10% and 40% of the fatigue life, respectively. In stress-controlled experiments the average positron lifetime at failure depends significantly on the applied stress amplitude. In strain-controlled experiments significantly different positron lifetimes for different applied plastic strain amplitudes are obtained within the first 1.000 fatigue cycles, whereas differences get wiped out during further cycling until failure.

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The influence of point-defect clusters on fatigue hardening of copper single crystals

Cited by 77 publications

References 29 publications

Microstructure and mechanisms of cyclic deformation of aluminum single crystals at 77 K

Microstructure and mechanisms of cyclic deformation of aluminum single crystals at 77 K

Effects of bending fatigue on the electrical resistance in metallic films on flexible substrates

Nondestructive monitoring of fatigue damage evolution in austenitic stainless steel by positron-lifetime measurements

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