Plastic anisotropy in a superplastic Al-Li-Mg-Cu alloy

Bate, P. S.

doi:10.1007/bf02647330

Cited by 23 publications

References 20 publications

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Superplasticity and microstructural evolution in aluminium alloys

Sotoudeh

Ridley

Humphreys

et al. 2012

Materialwissenschaft Werkst

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The fine‐grained microstructure required for superplasticity in commercial aluminium alloys is developed in one of two ways. In alloys such as AA5083 Al‐Mg‐Mn and AA7475 Al‐Zn‐Mg‐Cr, static recrystallisation produces an equiaxed microstructure prior to superplastic forming. In alloys such as AA2004 Al‐Cu‐Zr (SUPRAL) and AA8090 Al‐Li‐Mg‐Cu‐Zr, rolling and annealing prior to forming gives a recovered, ‘banded’ microstructure in which the subgrains evolve into grains defined by high angle boundaries during superplastic deformation. That banding‐ in terms of grain orientations‐ persists to much higher strains than would be expected if significant relative grain translation were occurring, and is not consistent with the widely accepted view that grain boundary sliding is the primary deformation mechanism during superplastic flow. To investigate this apparent anomaly further, work on statically recrystallised AA5083 was carried out. Examination of micro‐grid lines on sheet tensile specimens showed that intragranular slip made an insignificant contribution to superplastic flow. Examination of boundary offsets reinforced the view from work on Al‐Cu‐Zr and AA8090 that relative grain translation does not occur to any significant extent. The absence of significant intragranular slip and relative grain translation leads to the conclusion that diffusion creep is making a major contribution to the superplastic deformation.

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Superplasticity and microstructural evolution in aluminium alloys

Sotoudeh

Ridley

Humphreys

et al. 2012

Materialwissenschaft Werkst

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The absence of relative grain translation during superplastic deformation of an Al-Li-Mg-Cu-Zr alloy

Blackwell

Bate

1993

Metall Trans A

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The evolution of grain boundary character during superplastic deformation of an Al-6 pct Cu-0.4 pct Zr alloy

Eddahbi

Ruano

McNelley

2001

Metall Mater Trans A

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The evolution of microstructure, texture, and microtexture in an Al-6 pct Cu-0.4 pct Zr alloy was studied during mechanical testing at 480 ЊC and a strain rate of 5и10 Ϫ4 s Ϫ1 . The as-processed material had an elongated, banded microstructure and a deformation texture with orientation distribution along the ␤-orientation fiber. The true strain vs true stress curve exhibited three stages: I, II, and III. Work hardening occurred in stages I and III, whereas nearly steady-state behavior was observed in stage II. A bimodal distribution of boundary disorientation angles was evident in as-processed material and persisted into stage I, with peaks at 5-15 deg in the low-angle boundary (LAB) regime and at 45-60 deg in the high-angle boundary (HAB) regime. An increase in strain rate sensitivity coefficient, m, in stage I was accompanied by fragmentation of the initial microstructure, leading to the formation of new grains. During stage II the strain rate sensitivity coefficient, m, attained a value of 0.5, which is consistent with the onset of grain boundary sliding. In stage III, the texture and the grain boundary disorientation distribution became randomized while the m value decreased. Grain elongation and cavity formation at second-phase particles and along grain boundaries were seen in samples deformed to failure. The as-processed microstructure is described in terms of deformation banding, and a model for the evolution of such a structure during superplastic deformation is proposed.

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Plastic anisotropy in a superplastic Al-Li-Mg-Cu alloy

Cited by 23 publications

References 20 publications

Superplasticity and microstructural evolution in aluminium alloys

Superplasticity and microstructural evolution in aluminium alloys

The absence of relative grain translation during superplastic deformation of an Al-Li-Mg-Cu-Zr alloy

The evolution of grain boundary character during superplastic deformation of an Al-6 pct Cu-0.4 pct Zr alloy

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