Nucleation of Precipitates in AlZnMg alloys

Asano, Kazuhiko; Abe, Matanobu; Fujiwara, Akibumi

doi:10.1016/0025-5416(76)90135-x

Cited by 17 publications

(7 citation statements)

References 11 publications

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“…All of the researchers have concluded that the presence of elements in the solid solution and small particles possessing coherent interfaces increases the electrical resistivity. [20,22,23] Similar observations have also been reported in the case of 6XXX-series aluminum alloys. [21,[24][25][26] However, the information available on the effects of homogenization treatment on electrical resistivity is scarce in the literature, especially in the case of 7XXX-series aluminum alloys.…”

Section: Introductionsupporting

confidence: 83%

“…Ferragut [22] performed a pre-precipitation study on the AA7012 alloy by measuring its electrical resistivity. Asano [23] investigated the nucleation of precipitates in Al-Zn-Mg alloys using electrical resistivity measurements. All of the researchers have concluded that the presence of elements in the solid solution and small particles possessing coherent interfaces increases the electrical resistivity.…”

Section: Introductionmentioning

confidence: 99%

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Correlation between Electrical Resistivity, Particle Dissolution, Precipitation of Dispersoids, and Recrystallization Behavior of AA7020 Aluminum Alloy

Eivani

Ahmed

Zhou

et al. 2009

Metall Mater Trans A

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This research concerns the effect of homogenization treatment on the electrical resistivity of AA7020 aluminum alloy variants with different Zr and Cr contents. Small changes in the Zr and Cr contents of the as-cast alloy increase the electrical resistivity significantly. After employing various homogenization treatments, the electrical resistivity decreases, which is due to the depletion of Zr, Cr, and Mn in the matrix, by forming small dispersoids. The optimum treatment proposed in order to obtain the smallest recrystallized grains is to hold the material at 550°C for 24 hours, which results in the lowest electrical resistivity. The viability of the proposed treatment was tested through hot compression tests and static annealing. Indeed, the samples homogenized at 550°C for 24 hours showed the smallest recrystallized grains compared to those homogenized at other temperatures.

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Section: Introductionsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Correlation between Electrical Resistivity, Particle Dissolution, Precipitation of Dispersoids, and Recrystallization Behavior of AA7020 Aluminum Alloy

Eivani

Ahmed

Zhou

et al. 2009

Metall Mater Trans A

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“…The influence of storage time before subsequent artificial aging has also been studied, since it is known that a well-developed GP zone structure is favorable for the nucleation during artificial aging. [26] Besides, it has been found that time is required by T4 welds to achieve a homogeneous microstructure at room temperature ( Figure 8). …”

Section: Artificial Aging a T4 Weldmentioning

confidence: 98%

“…Thus, in this zone, it can be concluded that the thermal conditions do not result in significant changes of parameters like the vacancy concentration, which is known to have a large influence on the GP zone precipitation kinetics. [26] In the transition zone, where the minimum of precipitate volume fraction is encountered in the as-welded microstructure, the kinetics of GP zone formation is first slower. However, the variations of volume fraction and particle size in the T4 HAZ tend to disappear after 3 days at room temperature, when newly formed GP zones reach the characteristics of the pre-existing ones.…”

Section: Microstructures and Properties After Pwhtsmentioning

confidence: 99%

Precipitate microstructures and resulting properties of Al-Zn-Mg metal inert gas-weld heat-affected zones

Nicolás¹,

Deschamps

2004

Metall Mater Trans A

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Using the combination of small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), the precipitate microstructure is quantitatively investigated in the heat-affected zones (HAZs) of Al-Zn-Mg metal inert gas (MIG)-welds, and the resulting mechanical properties are determined by hardness measurements. Three initial states prior to welding (T4, T6, and T7) are investigated, and the subsequent microstructure evolution during natural aging and postwelding heat treatments (PWHTs) is assessed. The critical part of the HAZ is shown to be the transition region where partial dissolution of the initially present precipitates occurs. In this transition zone, precipitate coarsening is shown to occur for the T6 and T7 initial states, contrarily to the T4 material. After PWHT, the T6 and T7 materials experience a weak region related to this coarsening behavior, whereas the T4 material HAZ is able to recover a homogeneous microstructure after a suitably chosen PWHT. Simple model ramp heat treatments are shown to describe the main phenomena involved in the HAZ. Finally, a precipitation hardening model is successfully applied to the microstructural data to describe the hardness profiles in the various HAZs.

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“…Taking into account that the upper limit of GI' zone formation, T,,, in this A1-2.0 at.% Zn-1.4 at.% Mg alloy is approximately 120 "C (Koviics et al 1977 1982) we can conclude that VRC play an important role in the precipitation of the metastable (7') and even of the stable ( q ) phase when G P zones are not formed prior to or a t the beginning of the ageing at T,. et al 1979 andLACOM et al 1980;ASANO et al) and TEM (EMBURY, NICHOLSON;RYUM 1975;DEGISCHER et al;HOLL;RADOMSKI et al; UER-LACII, I A o~~~,~; investigations. The observations were interpreted in most cases by the formation of V l t C during the quench and/or during short ageing times (order of 10 sec) a t room temperature.…”

Section: Vrc As Nucleation Sites For Metastable and Stable Precipitatesmentioning

confidence: 94%

The effect of vacancy‐rich clusters on the decomposition processes in Al‐Zn‐Mg alloys

Lendvai

1984

Cryst. Res. Technol.

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1ntroduct)ionSince the early works of HARDY and POLMEAR the existence of vacancy-solute atom clusters (VRC) often turned up in the literature, in inost cases to explain the differences of the precipitate structures after different quenching treatments. The aim of this paper is to review the results concernirtg the forrnation of the VHC and their effect on the decortipsition processes. VRC as nucleation sites for metastable and stable precipitatesThe existence of VRC has been assumed to explain the differences in the precipitate structure of Al-Zn-Mg alloys after direct quench, UQ, and indirect quench, 1&, to the ageing temperature, T,. I n case of 1Q the alloy is generally water quenched to 0 or 20 "C, kept at this temperature for a short time (order of one minute) and thereafter aged at T,. 1982) we can conclude that VRC play an important role in the precipitation of the metastable (7') and even of the stable ( q ) phase when G P zones are not formed prior to or a t the beginning of the ageing at T,. I A o~~~,~;~ 1982.) investigations. The observations were interpreted in most cases by the formation of V l t C during the quench and/or during short ageing times (order of 10 sec) a t room temperature. The VltC then act as nucleation sites for the precipitation of the metastable or stable precipitates when the alloy is up-quenched to T, > TI,. I t is generally agreed (L~FELER et al. 1983) that the number of VRC depends sensitively on the quench procedure, i.e. on the temperature of solution treatment and of the quenching bath, on the quenching rate (e.g. air cooling, oil quench, water quench etc.) or on conditions of step quenching. Above a certain critical temperature, which depends on the alloy composition and on the quenching procedure, VRC are not formed and consequently the precipitation of the metastable or stable precipitates l)

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Nucleation of Precipitates in AlZnMg alloys

Cited by 17 publications

References 11 publications

Correlation between Electrical Resistivity, Particle Dissolution, Precipitation of Dispersoids, and Recrystallization Behavior of AA7020 Aluminum Alloy

Correlation between Electrical Resistivity, Particle Dissolution, Precipitation of Dispersoids, and Recrystallization Behavior of AA7020 Aluminum Alloy

Precipitate microstructures and resulting properties of Al-Zn-Mg metal inert gas-weld heat-affected zones

The effect of vacancy‐rich clusters on the decomposition processes in Al‐Zn‐Mg alloys

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