The stress dependence of the subgrain size in aluminium

Ginter, Timothy J.; Mohamed, Farghalli A.

doi:10.1007/bf00540418

Cited by 45 publications

(15 citation statements)

References 12 publications

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“…[3] predicts the average subgrain size to within a factor of 3. [25,27] The substructural data of 99.999 Pb that, unlike 99.95 Pb, exhibited accelerated creep rates in the region of Harper-Dorn region provide evidence that dynamic recrystallization is the dominant restoration mechanism. Such evidence is based on the following observations: (a) nucleation of new grains, (b) absence of large subgrains or well-developed sub-boundaries in the interiors of grains, and (c) the presence of twins.…”

Section: B Restoration Processmentioning

confidence: 94%

“…This conclusion is based in part on the observation that very large subgrains or triple joints of subgrains are formed during the creep of 99.95 Pb. It is well-documented that when the normalized average subgrain size, d/b, in metals is plotted, a function of the normalized stress, s/G, on a logarithmic scale, data can be described by a single straight line obeying the equation: [25,27] d=b…”

Section: B Restoration Processmentioning

confidence: 99%

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Uncovering the Mystery of Harper–Dorn Creep in Metals

Cheng

Chauhan

Mohamed

2008

Metall Mater Trans A

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In the present investigation, the occurrence of Harper-Dorn creep in Pb was studied under the condition of large strains. In performing the study, two Pb grades, commercial-purity Pb (99.95 pct) and high-purity Pb (99.999 pct), were creep tested at 573 K. The mechanical data showed that 99.95 Pb, unlike 99.999 Pb, did not exhibit accelerated creep rates at stresses <0.1 MPa (the region of Harper-Dorn creep). Also, the data on 99.999 Pb revealed that the creep curves associated with Harper-Dorn creep exhibited periodic accelerations and that the stress exponent was approximately 3, not unity as previously reported for Pb and other materials. An examination of the substructure developed during creep revealed that the substructural details in 99.95 Pb were markedly different from those characterizing Harper-Dorn creep in 99.999 Pb. In 99.95 Pb, the substructural observations included the presence of very large subgrains and triple junctions of subgrains. By contrast, in 99.999 Pb, the substructural features included the nucleation of new grains and the presence of twins. Combining the present data on Pb and those reported recently for Al has led to three important conclusions. First, the accelerated creep rates noted in the region of Harper-Dorn creep are produced by a creep process for which the dominant restoration mechanism is dynamic recrystallization. Second, the linear-stress dependence of creep rate previously reported for Harper-Dorn creep is most probably a direct consequence of short-term measurements involving small strains (total creep strains £0.01). Finally, Harper-Dorn creep will be observed in a large-grained metal at very low stresses if its purity level is high. This condition favors dynamic recrystallization as a restoration mechanism.

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Section: B Restoration Processmentioning

confidence: 94%

Section: B Restoration Processmentioning

confidence: 99%

Uncovering the Mystery of Harper–Dorn Creep in Metals

Cheng

Chauhan

Mohamed

2008

Metall Mater Trans A

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“…(2) to a modified exponent m = 4/n in the d ∝ τ -m relation [41]. In fact there were carried out high-temperature low-stress tensile creep experiments on Al where d = 5000 µm and m = 0.54 have been obtained [79]. Even an exponent of m = 0.13 was reported for creep tests on Nb [80].…”

Section: Origins Of Cell Patterningmentioning

confidence: 96%

Dislocation cell structures in melt‐grown semiconductor compound crystals

Rudolph

2004

Cryst. Res. Technol.

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The phenomenon of dislocation patterning during melt growth of III-V, II-VI and IV-VI semiconductor crystals is discussed. The paper is focused on the formation of cellular structures driven by the growth inherent thermo-mechanical stress. Of particular interest is the scaling of relations between cells size, dislocation density and acting shear stress. Among the materials there are characteristic similarities but also significant variations of the cell genesis. After the related compound specifics are discussed possible measures for retardation of cell patterning during growth are demonstrated.

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“…In the above, tau is the resolved shear stress on the loop. Therefore, for the applied stress or, τ a = τ o + αMGbρ 1/2 (8) or Equation (1), which is the classic Taylor equation, with, in this case, a τ o that is a significant fraction of the flow stress. Thus, this article fundamentally confirms that dislocation hardening within the fivepower-law creep regime, can be described by a classic Taylor equation using a linear superposition of a dislocation hardening term and a solute strengthening term.…”

Section: Analysis and Discussionmentioning

confidence: 99%

“…It must be mentioned that the basis for strengthening in five power-law -creep in generally attributed to the Frank dislocation network such as [4][5][6][7]. Others have held to the proposition that subgrain walls are associated with the strength of materials within the five-power-law regime [8,9]. This Communication considers the Frank network to be associated with strength and the rate-controlling process for creep.…”

Section: Introductionmentioning

confidence: 99%

Application of the Taylor Equation to Five-Power-Law Creep Considering the Influence of Solutes

Kassner

2018

Metals

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This study determines the feasibility of describing the flow stress within the five-power-law creep regime, using a linear superposition of a dislocation hardening term and a significant solute strengthening term. It is assumed that the solutes are randomly distributed. It was found that by using an energy balance approach, the flow stress at high temperatures can be well-described by the classic Taylor equation with a solute strengthening term, τo, that is added to the αMGbρ1/2 dislocation hardening term.

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The stress dependence of the subgrain size in aluminium

Cited by 45 publications

References 12 publications

Uncovering the Mystery of Harper–Dorn Creep in Metals

Uncovering the Mystery of Harper–Dorn Creep in Metals

Dislocation cell structures in melt‐grown semiconductor compound crystals

Application of the Taylor Equation to Five-Power-Law Creep Considering the Influence of Solutes

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