On the Influence of Small Magnesium Additions on the Decomposition Behaviour of an AlZn (6 at%) Mother Alloy

Löffler, H.; Gould, R. W.

doi:10.1002/pssa.2210720114

Cited by 2 publications

(1 citation statement)

References 23 publications

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“…The role of VItC in the formation of q' particles is relatively more significant in the case of lower concentration alloys, because in more concentrated alloys GP zones very soon attain a size which makes them suitable for q' nucleation. The density of nucleation sites as a function of ageing time a t room temperature for these alloys with different %n concentrations is schematically shown in Figure 4 (RADOMESKY et al; KovAcs et al;LOFFLER et al 1981).…”

Section: The Formation and Stability Of Vrcmentioning

confidence: 98%

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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Section: The Formation and Stability Of Vrcmentioning

confidence: 98%

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

Lendvai

1984

Cryst. Res. Technol.

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The influence of small Mg additions on the stability of guinier-preston zones in Al4.5 at% ZnxMg alloys

Löffler

Wendrock

Pawelzyk

1987

Phys. Stat. Sol. (a)

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The influence of small Mg additions (xMg ≦ 0.20 at%) on the upper Limit temperature T GPZdiss of the existence of Guinier‐Preston (GP) zones is determined by SAXS investigations. In order to avoid falsifications by the size dependence of T GPZdiss, in all cases, the reversion treatments start with GP zones having a mean size of RK = (2.1 ± 0.2) nm. The main results are: (i) up to xMg = 0.10 at% T GPZdiss = (118 ± 3)°C, i.e. only few Mg atoms are inserted into the GP zones, but if adding 0.20 at% Mg to the Al4.5 at% Zn mother alloy T GPZdiss is raised to (152 ± 3)°C; (ii) the solubility of Mg in the matrix of the Al4.5 at% Zn mother alloy is less than 0.20 at%.

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On the Influence of Small Magnesium Additions on the Decomposition Behaviour of an AlZn (6 at%) Mother Alloy

Cited by 2 publications

References 23 publications

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

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

The influence of small Mg additions on the stability of guinier-preston zones in Al4.5 at% ZnxMg alloys

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