Evidence of η″ or ordered zone formation in aluminum alloy 7075 from differential scanning calorimetry

Bartges, C.

doi:10.1016/0956-716x(93)90006-e

Cited by 12 publications

(1 citation statement)

References 3 publications

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“…At ageing temperatures below approximately 180 • C, the first stage of decomposition is the formation of spherical solute-rich clusters (Guinier-Preston, or GP, zones). At later stages, semicoherent precipitates (η -particles) with composition Mg(Zn, Al, Cu) 2 appear, which evolve, with no substantial composition change, into bigger particles of the incoherent equilibrium phase η [1]. The sequence of steps in the decomposition process depends on the composition of the alloy, on the quenching conditions, on the ageing temperatures, etc (for a review see [2]).…”

Section: Introductionmentioning

confidence: 99%

On the two-step ageing of a commercial Al - Zn - Mg alloy; a study by positron lifetime spectroscopy

Ferragut

Somoza

Dupasquier

1996

J. Phys.: Condens. Matter

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Formation of Guinier - Preston zones and precipitation, induced by two-step ageing thermal treatments in an age-hardenable commercial Al - Zn - Mg-based alloy, have been studied by positron lifetime spectroscopy and Vickers microhardness measurements. In particular, an initial softening of the specimens, occurring in the early stages of the second ageing step (artificial ageing at ), appears to be correlated with a strong decrease in the positron lifetime, which indicates a partial dissolution of the GP zones. If the treatment at is interrupted at this stage, and the ageing continues at a lower temperature (either room temperature or ), the positron lifetime and the microhardness recover to the values reached at the end of the first ageing step (natural ageing at room temperature for five days). The kinetics of this process is discussed in terms of reconstruction of GP zones; the activation energy value of this process is also obtained.

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Section: Introductionmentioning

confidence: 99%

On the two-step ageing of a commercial Al - Zn - Mg alloy; a study by positron lifetime spectroscopy

Ferragut

Somoza

Dupasquier

1996

J. Phys.: Condens. Matter

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Changes in solid solution composition as a function of artificial ageing time for aluminium alloy 7075

Bartges

1994

Journal of Materials Science Letters

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Microstructure and Cyclic Deformation Behavior of a Friction-Stir-Welded 7075 Al Alloy

Feng

Chen

2010

Metall Mater Trans A

119

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Microstructural changes and cyclic deformation characteristics of friction-stir-welded 7075 Al alloy were evaluated. Friction stir welding (FSW) resulted in significant grain refinement and dissolution of g¢ (Mg(Zn,Al,Cu) 2 ) precipitates in the nugget zone (NZ), but Mg 3 Cr 2 Al 18 dispersoids remained nearly unchanged. In the thermomechanically affected zone (TMAZ), a high density of dislocations was observed and some dislocations were pinned, exhibiting a characteristic Orowan mechanism of dislocation bowing. Two low-hardness zones (LHZs) between the TMAZ and the heat-affected zone (HAZ) were observed, with the width decreasing with increasing welding speed. Cyclic hardening and fatigue life increased with increasing welding speed from 100 to 400 mm/min, but were only weakly dependent on the rotational rate between 800 and 1200 rpm. The cyclic hardening of the friction-stir-welded joints exhibiting a two-stage character was significantly stronger than that of the base metal (BM) and the energy dissipated per cycle decreased with decreasing strain amplitude and increasing number of cycles. Fatigue failure occurred in the LHZs at a lower welding speed and in the NZ at a higher welding speed. Fatigue cracks initiated from the specimen surface or near-surface defects in the friction-stirwelded joints, and the initiation site exhibited characteristic intergranular cracking. Crack propagation was characterized by typical fatigue striations along with secondary cracks.

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Evidence of η″ or ordered zone formation in aluminum alloy 7075 from differential scanning calorimetry

Cited by 12 publications

References 3 publications

On the two-step ageing of a commercial Al - Zn - Mg alloy; a study by positron lifetime spectroscopy

On the two-step ageing of a commercial Al - Zn - Mg alloy; a study by positron lifetime spectroscopy

Changes in solid solution composition as a function of artificial ageing time for aluminium alloy 7075

Microstructure and Cyclic Deformation Behavior of a Friction-Stir-Welded 7075 Al Alloy

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