Mechanical behaviour of an aluminium alloy with fusible grain boundaries

Baudelet, B.; Dang, Min; Bordeaux, F.

doi:10.1016/0956-716x(92)90286-n

Cited by 31 publications

(13 citation statements)

References 27 publications

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“…In contrast, high wettability (low dihedral angle) melts thickly coating grain boundaries produced premature necking and creep failure due to the loss of grain boundary cohesion [Mabuchi et al, 1997;Koike et al, 1998]. The same transition from superplastic flow to premature failure coinciding with almost complete wetting of grain boundaries (at length proportion of 70%) was demonstrated also during compressive experiments [Pharr et al, 1989;Baudelet et al, 1992].…”

Section: Effect Of Melt Phase On Gbsmentioning

confidence: 83%

Extreme ductility of feldspar aggregates—Melt‐enhanced grain boundary sliding and creep failure: Rheological implications for felsic lower crust

Závada

Schulmann²,

Konopásek

et al. 2007

J. Geophys. Res.

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[1] High-grade orthogneisses from granulite-bearing lower crustal unit show extreme finite strains of both K-feldspar and plagioclase with respect to weakly deformed quartz aggregates. K-feldspar aggregate in the most intensely deformed sample shows interstitial grains of quartz and albite, which also mark some intragranular fractures within K-feldspar grains. Both interstitial grains and fractures are oriented mostly perpendicular to the sample stretching lineation. Quartz and albite grains within K-feldspar bands are interpreted as crystallized from interstitial melt and the petrology study shows that the melt was produced by a metamorphic reaction in plagioclase-mica bands. Thermodynamic Perple_X modeling shows that melt volume increase was negligible and melt amount was too small to generate considerable melt overpressure for calculated PT conditions. It is therefore suggested that dilation of K-feldspar aggregates and fracturing of its grains represent a final creep failure state, which resulted from the cavitation process accompanying grain boundary sliding controlled diffusion creep. The consequence of cavitation-driven dilation of K-feldspar aggregates is the local underpressure resulting in infiltration of melt from plagioclase bands. Analogy with metallurgy experiments shows that the cavitation process, exclusively developed in cryptoperthitic K-feldspar, can be attributed to its lower purity compared to more pure plagioclase. Contrasting rheological behavior of feldspars with respect to quartz prior to fracturing is attributed to different deformation mechanisms. Feldspars appear weaker due to grain boundary sliding accommodated by coupled melt-enhanced diffusion creep along grain boundaries and dislocation creep within grains, in contrast to quartz deforming via grain boundary migration accommodated dislocation creep.Citation: Závada, P., K. Schulmann, J. Konopásek, S. Ulrich, and O. Lexa (2007), Extreme ductility of feldspar aggregates-Meltenhanced grain boundary sliding and creep failure: Rheological implications for felsic lower crust,

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Section: Effect Of Melt Phase On Gbsmentioning

confidence: 83%

Extreme ductility of feldspar aggregates—Melt‐enhanced grain boundary sliding and creep failure: Rheological implications for felsic lower crust

Závada

Schulmann²,

Konopásek

et al. 2007

J. Geophys. Res.

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“…This indicates that a much larger volume fraction of liquid does not contribute to large elongations. 19) Increasing volume fraction of liquid phase at 600…”

Section: The Role Of Cumentioning

confidence: 99%

Effect of Cu and Zr Additions on the Superplastic Behavior of 6061 Aluminum Alloy

et al. 2002

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Experiments were conducted to evaluate the influence of zirconium and copper additions on superplastic behavior of a 6061 aluminum alloy. Fine grains were produced in a commercial grade of 6061 Al and a 0.15%Zr + 0.7%Cu-modified 6061 alloy by two-step thermomechanical processing. The superplastic properties and microstructure evolution of both alloys were examined in tension at temperatures ranging from 475 to 620 • C and strain rates ranging from 7 × 10 −6 to 2.8 × 10 −2 s −1 . It was shown using differential thermal analysis that both alloys exhibit the highest superplastic characteristics in a partially melted state. The 0.15%Zr + 0.7%Cu-modified 6061 aluminum alloy exhibits a maximum elongation-to-failure of 1300% at 590 • C and an initial strain rate of 2.8 × 10 −4 s −1 . In contrast, the highest total elongation of 350% (m ∼ 0.6) was achieved in the commercial grade 6061 alloy at 600 • C and a strain rate of 1.4 × 10 −4 s −1 . The results suggest the addition of Zr provides high stability of the fine-grained structure under superplastic deformation at high temperatures by precipitation of Al 3 Zr dispersoids. Apparently, the increased amount of liquid phase caused by the copper addition can enhance the superplastic properties of the 6061 alloy.

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“…The polycrystals containing a thin liquid-like layer in GBs become very ductile. For example, the unusual superplasticity with maximal elongation of up to 2500% has been observed in the Al-Zn-Mg UFG polycrystals [115][116][117][118][119]. This phenomenon appeared in the very narrow temperature interval below the solidus line.…”

Section: Discussionmentioning

confidence: 95%

Grain Boundary Complexions and Phase Transformations in Al- and Cu-Based Alloys

Kogtenkova

Straumal

Korneva

et al. 2018

Metals

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High-pressure torsion has been used to obtain the ultra-fine grained (UFG) state with a high specific area of grain boundaries (GBs) in Al-Zn, Al-Mg, Cu-Ag, Cu-Co, and Cu-Ni solid solutions with face-centered cubic (fcc) lattices. The UFG samples were heated in a differential scanning calorimeter (DSC). Small endothermic peaks in the DSC curves were observed in the one-phase solid-solution area of the respective phase diagrams, i.e., far away from the bulk solidus and solvus lines. A possible explanation of these endothermic peaks is based on the hypothesis of phase transformations between GB complexions. This hypothesis has been supported by observations with transmission electron microscopy and electron backscattering diffraction. The new lines of GB phase transformations have been constructed in the Al-Zn, Al-Mg, Cu-Ag, Cu-Co, and Cu-Ni bulk phase diagrams.

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Mechanical behaviour of an aluminium alloy with fusible grain boundaries

Cited by 31 publications

References 27 publications

Extreme ductility of feldspar aggregates—Melt‐enhanced grain boundary sliding and creep failure: Rheological implications for felsic lower crust

Extreme ductility of feldspar aggregates—Melt‐enhanced grain boundary sliding and creep failure: Rheological implications for felsic lower crust

Effect of Cu and Zr Additions on the Superplastic Behavior of 6061 Aluminum Alloy

Grain Boundary Complexions and Phase Transformations in Al- and Cu-Based Alloys

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