Formation of dislocation structures during cyclic deformation of F.C.C. crystals—I. Formation of PSBs in crystals oriented for single-slip

Jin, N.Y.

doi:10.1016/0001-6160(89)90091-6

Cited by 55 publications

(12 citation statements)

References 23 publications

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“…Fig. 7 (top) shows that condensation mode B also includes the nucleation of new PSBs in the form of extremely thin PSB lamellae, as observed by Jin [44] at low epa values, comparable to eM = 1.9 x Regarding the PSB wall structures observed in the present study, it is relevant to emphasize similarities with the observations by Mughrabi et al [21] on single slip oriented copper cycled to comparable values of ecum. In particular, both studies 1 Fig.…”

Section: Successive Condensation Modessupporting

confidence: 88%

“…1 is drawn primarily on the basis of Mughrabi's [42] observations of V, minima. More recent measurements show V, minima [43,44] occurring at somewhat higher cycle numbers. Specimen B3 (Table 1) was cycled beyond these recent V, minima but not into stage III,, and TEM investigation of specimen B3 gave frequent observations of embryonic PSB walls formed by collapse of veins, see Fig.…”

Section: Successive Condensation Modesmentioning

confidence: 99%

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Cyclic hardening and slip localization in single slip oriented copper crystals

Pedersen

Winter²

1995

Phys. Stat. Sol. (a)

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A static-dynamic model is applied to the interpretation of slip localization modes observed in a systematic study of the evolution of dislocation structures in single slip intermediate amplitude fatigue in copper deformed at room temperature. The model assumes that veins do not deform plastically, unless their critically soft interiors are destabilized to produce an embryonic PSB. This assumption is shown to be fully consistent with slip homogeneity. The model predicts that the vein structure remains active during cyclic saturation. This prediction explains the present novel observation that in intermediate amplitude fatigue, after the initial formation of PSBs by ''collapse'' of matrix walls, triggered by long-range internal stresses, there is continued formation of new PSBs by "splitting" of matrix veins. The model shows that the long-range internal stresses in the thin PSB lamellae and in the more extended wall structures produced by this process are about equal. Nevertheless, the model and microscopy suggest convincingly that minimization of dislocation line energy in the dynamic structure between glissile walls and veins controls the condensation mode and the equilibrium wall spacing of PSBs.') DK-4000 Roskilde, Denmark. ' ) Madingley Road, Cambridge CB3 OHE, England.

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Section: Successive Condensation Modessupporting

confidence: 88%

Section: Successive Condensation Modesmentioning

confidence: 99%

Cyclic hardening and slip localization in single slip oriented copper crystals

Pedersen

Winter²

1995

Phys. Stat. Sol. (a)

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“…This is consistent with the results of Merlin et al density with increase in the predeformation level in the oxide dispersion strengthened nickel base alloy MA754 tested at 760°C. Similar results could also be deducted from the work of Jin [23] where deformed copper crystals exhibited an increase in surface persistent slip bands with the increase in the applied plastic strain amplitude.…”

Section: Resultssupporting

confidence: 83%

Role of Predeformation in the Modification of Crack Tip Oxidation Resistance

1993

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The effects of predeformation on the high temperature, low frequency crack growth rate of wrought Alloy 718 is investigated. A series of crack growth experiments were carried out on specimens with different levels of deformation, in addition to specimens in the as received conditions. The experiments included continuous measurements of the crack length and its near field crack tip displacements, fractographic analysis of fracture surface facets and qualitative estimation of the slip density in the crack tip region. Furthermore the thickness of surface oxide layers formed during the fracture process was determined using Auger Spectroscopy. Results of this study show that predeformation enhances the crack tip resistance to environmental effects. This result has been analyzed on the basis of the concept that the deformation-associated slip line density controls the chromium oxide build up taking place along the effected grain boundaries in the crack tip region.

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“…Dislocations are generally undesired in semiconductors and ceramics2425 when the thermal conductivity is not a major functionality, due to their detrimental effects on the mechanical properties, carrier mobility and optical properties262728. To achieve an effective κ L reduction by dislocations in thermoelectric semiconductors, a simple estimation shows that the density of uniformly distributed dislocations within the grains ( N D ) needs to be approaching 10 12 cm −2 or higher29, being at least two orders of magnitude higher than that can be normally obtained in semiconductors30.…”

mentioning

confidence: 99%

Vacancy-induced dislocations within grains for high-performance PbSe thermoelectrics

et al. 2017

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To minimize the lattice thermal conductivity in thermoelectrics, strategies typically focus on the scattering of low-frequency phonons by interfaces and high-frequency phonons by point defects. In addition, scattering of mid-frequency phonons by dense dislocations, localized at the grain boundaries, has been shown to reduce the lattice thermal conductivity and improve the thermoelectric performance. Here we propose a vacancy engineering strategy to create dense dislocations in the grains. In Pb1−xSb2x/3Se solid solutions, cation vacancies are intentionally introduced, where after thermal annealing the vacancies can annihilate through a number of mechanisms creating the desired dislocations homogeneously distributed within the grains. This leads to a lattice thermal conductivity as low as 0.4 Wm−1 K−1 and a high thermoelectric figure of merit, which can be explained by a dislocation scattering model. The vacancy engineering strategy used here should be equally applicable for solid solution thermoelectrics and provides a strategy for improving zT.

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Formation of dislocation structures during cyclic deformation of F.C.C. crystals—I. Formation of PSBs in crystals oriented for single-slip

Cited by 55 publications

References 23 publications

Cyclic hardening and slip localization in single slip oriented copper crystals

Cyclic hardening and slip localization in single slip oriented copper crystals

Role of Predeformation in the Modification of Crack Tip Oxidation Resistance

Vacancy-induced dislocations within grains for high-performance PbSe thermoelectrics

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