Effect of impurity content on superplastic flow in the Zn-22% Al alloy

Chaudhury, Prabir K.; Mohamed, Farghalli A.

doi:10.1016/0001-6160(88)90163-0

Cited by 137 publications

(100 citation statements)

References 34 publications

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“…Recent creep data reported for several grades of Zn-22%Al containing different levels of impurities, 37,42,43 particularly Fe, have revealed the presence of a threshold stress whose characteristics are consistent with various phenomena associated with boundary segregation, as summarized below:…”

Section: Threshold Stressmentioning

confidence: 70%

“…3(a)]; 38,42,43 for Zn-22%Al, the apparent stress exponent and the apparent activation energy for creep in region I, unlike those in region II, are sensitive to impurity content [ Fig. 3(b)]; 42 and for constant temperature, the transition between region II and region I is transposed 37 to lower strain rates with decreasing level of Fe; and region I is absent in Zn-22%Al when the alloy is doped with Cu, 44 whereas this region is observed when the alloy is doped with a comparable atomic level of Fe [ Fig. 3(c)].…”

Section: Roles Of Boundaries During Superplastic Deformationmentioning

confidence: 99%

“…Recent results 45 reported for the activity of lattice dislocations during the superplastic deformation of Pb-62%Sn in region II have suggested that lattice dislocations play a dual role: they accommodate boundary sliding; and when absorbed into boundaries they serve as a source of mobile boundary dislocations. It is possible that at low stresses typical of region I, lattice dislocations drag impurity atmospheres 42,43,46 and, as a result, the glide of these dislocations in the interiors of the grains from the source (the edge of sliding grains) to the sink (boundaries) can proceed no faster than the rate of impurity diffusion. If it is assumed that dislocations glide in a single plane (one-dimensional array) and that the rate of glide is slower than the rate of climb, the creep rate is given by 47 …”

Section: Roles Of Boundaries During Superplastic Deformationmentioning

confidence: 99%

“…(1) No threshold stress, o , is observed for superplastic flow in high-purity Zn-22%Al 42,43 ( Fig. 5(a)).…”

Section: Threshold Stressmentioning

confidence: 99%

“…A similar trend for high-purity Pb-62%Sn was reported. 38 As reported elsewhere, 37,38,42,43,53 o is determined from experimental creep data obtained for a superplastic alloy by plotting P 1/n n D 2.5 against at a single temperature on a double linear scale and extrapolating the resultant line to zero strain rate. …”

Section: Threshold Stressmentioning

confidence: 99%

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The role of boundaries during superplastic deformation

Mohamed

2001

Surface & Interface Analysis

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Micrograin superplasticity refers to the ability of fine-grained materials (d < 10 µm, where d is the grain size) to exhibit extensive neck-free elongations during deformation at elevated temperatures (T > 0.5 T m , where T m is the melting point). Consideration of recent experimental data regarding the effects of impurities on the characteristics of micrograin superplasticity reveals an important role played by boundaries in superplastic alloys. This role pertains to the ability of boundaries to serve as favorable sites for the accumulation of impurities, i.e. boundary segregation. Evidence in support of boundary segregation during micrograin superplasticity is reviewed, with particular emphasis on creep behavior, cavitation, ductility, boundary sliding and the formation of cavity stringers.

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Section: Threshold Stressmentioning

confidence: 70%

Section: Roles Of Boundaries During Superplastic Deformationmentioning

confidence: 99%

Section: Roles Of Boundaries During Superplastic Deformationmentioning

confidence: 99%

“…(1) No threshold stress, o , is observed for superplastic flow in high-purity Zn-22%Al 42,43 ( Fig. 5(a)).…”

Section: Threshold Stressmentioning

confidence: 99%

Section: Threshold Stressmentioning

confidence: 99%

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The role of boundaries during superplastic deformation

Mohamed

2001

Surface & Interface Analysis

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Superplasticity of Bulk Nanostructured Materials

Langdon

2009

Bulk Nanostructured Materials

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Achieving a Superplastic Forming Capability through Severe Plastic Deformation

Furukawa

Horita

et al. 2003

Adv Eng Mater

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Processing by severe plastic deformation (SPD) leads to very significant grain refinement in metallic alloys. Furthermore, if these ultrafine grains are reasonably stable at elevated temperatures, there is a potential for achieving high tensile ductilities, and superplastic elongations, in alloys that are generally not superplastic. In addition, the production of ultrafine grains leads to the occurrence of superplastic flow at strain rates that are significantly faster than in conventional alloys so that processing by SPD introduces the possibility of using these alloys for the rapid fabrication of complex parts through superplastic forming operations. This paper examines the development of superplasticity in various aluminum alloys processed by equal‐channel angular pressing (ECAP).

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Effect of impurity content on superplastic flow in the Zn-22% Al alloy

Cited by 137 publications

References 34 publications

The role of boundaries during superplastic deformation

The role of boundaries during superplastic deformation

Superplasticity of Bulk Nanostructured Materials

Achieving a Superplastic Forming Capability through Severe Plastic Deformation

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