A Possible Origin of Exo-Electron Emission in Plastically Deformed Metals

Meleka, A. H.; Barr, Warren

doi:10.1038/187232a0

Cited by 24 publications

(5 citation statements)

References 6 publications

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“…The response that develops is described as "Cyclic creep acceleration" when the creep rate during both transient and steady state creep stages is higher under cyclic creep conditions than that under static conditions for the same maximum stress (LORENZO and LAIRD 1984). Cyclic creep acceleration has been observed in Aluminum , SHETTY and M. MESHII 1975), Copper (FELTNER 1963, MELEKA and EVERSHED 1960) Lead (KENNEDY 1963 and Al-Zn system (BLUM et al 1989). LORENZO and LAIRD (1984) have reported the existence of a threshold for cyclic creep acceleration for the case of copper polycrystals at ambient temperature, whereas SHETTY and MESHII (1975) reported the same phenomenon for the case of pure Aluminum with 100% unloading.…”

Section: Introductionmentioning

confidence: 99%

“…LORENZO and LAIRD (1984) have reported the existence of a threshold for cyclic creep acceleration for the case of copper polycrystals at ambient temperature, whereas SHETTY and MESHII (1975) reported the same phenomenon for the case of pure Aluminum with 100% unloading. Interpretation the phenomenon of cyclic creep acceleration has been attempted by many authors (MELEKA and EVERSHED 1960, EVANS and PARKINS 1976, BENNET and EVANS 1979, KÖNIG and BLUM (1980, LAIRD 1982, 1984).…”

Section: Introductionmentioning

confidence: 99%

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Effect of Cyclic Stress Reduction on the Creep Behaviour of Al-Ag and Al-Ag-Zr Alloys Containing γ′ and γ Precipitates

Graiss

Mahmoud

2000

Cryst. Res. Technol.

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Cryst. Res. Technol. 352000 1 95-100Creep tests under the effect of cyclic stress reduction were conducted to Al-16 wt %Ag and Al-16 wt %Ag-0.1 wt %Zr alloys aged at 548 and 673 K. The steady state creep rate was found to be higher under cyclic stress reduction condition than that under static creep condition for the same maximum stress. An expression for the temperature dependence of the threshold stress for cyclic creep acceleration is offered. Cyclic creep acceleration is interpreted using the dislocation cross-slip model. TEM investigations confirmed that the addition of Zr to Al-Ag alloy accelerates the formation and coarsening of γ \ and γ-phases. The mean value of activation energy for both alloys aged at 548 K was found to be 35±0.3 kJ/mol, and 58±0.4 kJ/mol for alloys aged at 673 K.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Cyclic Stress Reduction on the Creep Behaviour of Al-Ag and Al-Ag-Zr Alloys Containing γ′ and γ Precipitates

Graiss

Mahmoud

2000

Cryst. Res. Technol.

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“…17,18,[28][29][30][31][32][33][34][35][36][37][38][39][40] Electron microscopy, autoradiographic stripping, 29 and photoemission spectroscopy 17,37 showed that these signals were closely associated with the formation of slip lines and bands on deformed surfaces. 17,18,[28][29][30][31][32][33][34][35][36][37][38][39][40] Electron microscopy, autoradiographic stripping, 29 and photoemission spectroscopy 17,37 showed that these signals were closely associated with the formation of slip lines and bands on deformed surfaces.…”

Section: Discussionmentioning

confidence: 99%

Determination of strain localization in aluminum alloys using laser-induced photoelectron emission

Cai

Langford

Levine

et al. 2004

Journal of Applied Physics

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Articles you may be interested inThe effect of thermal oxidation on laser-induced photoelectron emission during tensile deformation of polycrystalline aluminum J. Appl. Phys. 107, 053526 (2010); 10.1063/1.3327237Laser-induced spallation of aluminum and Al alloys at strain rates above 2 × 10 6 s − 1 Uniaxial tensile deformation of oxidized aluminum produces low work-function patches of fresh metal which can be probed by measurements of photoelectron emission during exposure to ultraviolet light. We report measurements of photoelectron emission during uniaxial testing of polycrystalline Al(1200), Al-Mn(3003), Al-Mg(5052), and Al-Mg-Si(6061) alloys where the broad face of the gauge section is exposed to pulsed excimer laser radiation ͑248 nm͒. We show that strain localization alters the distribution of fresh surface metal produced by subsequent deformation. The transition from more homogenous deformation to the principally localized deformation associated with shear bands is associated with a discontinuity in the growth rate of photoelectron intensities versus time. At this transition, the rate of fresh metal production along the illuminated portion of gauge section decreases. In all four materials, the strain at the discontinuity is somewhat below the strain given by the Considère criterion, consistent with the role of microstructural effects in strain localization. We suggest that these photoelectron measurements constrain quantitative models of strain localization.

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“…It is also found that the effect of the former can be weakened by localized and dynamic loading in vacuum (Mints and Kortov, hmission caused by the deformation of the lattice must be associated with dislocations or point defects. This is demonstrated by the correspondence between the darkened spots on the emulsion applied to a statically strained zinc single crystal and dislocation etch pits along the slip lines (Meleka and Barr. 1960), and by the emission of electrons from aluminum after quenching Iron temperatures between 3(30° and 450° C (Claytor et al 1966} The release of electrons can be facilitated by lowering the work function of the metal surface, since change in the contact potential with strain in molybdenum and tantalum indicates that the work function of these metals is reduced as a result of plastic defomation Palige.…”

Section: Exoelectron Emissionmentioning

confidence: 94%