Effect of Magnesium on the Clustering in Al-Zn-Mg Alloys

Ohta, Mutsuo; Hashimoto, Fumio

doi:10.1143/jpsj.19.130

Cited by 18 publications

(4 citation statements)

References 2 publications

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“…This indicates that in these alloys two different types of zones are formed during a short time after quenching and only the more stable ones exist after longer aging times at RT. The two dissolution peaks in the alloys containing less than 0.5 at% Mg indicate the formation of two types of zones which are most probably near to the composition of the ones due to the binary A1-Zn and ternary AI-Zn-Mg alloys in accordance with earlier investigations [17][18][19]. Some characteristic temperatures of the peaks in the thermograms obtained after six months RT aging are shown in Fig.…”

Section: Resultssupporting

confidence: 88%

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The influence of Mg content on the formation and reversion of Guinier-Preston zones in Al-4.5 at % Zn-x Mg alloys

et al. 1981

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The influence of Mg concentrations on the dissolution of Guinier-Preston (GP) zones formed at room temperature (RT) and on the formation of more stable phases has been investigated during continuous heating of AI-4.5 at% Zn-xMg alloys. The Mg content was varied from 0.05 to 3 at %. After different aging periods at RT, calorimetric investigations were carried out at heating rates of 40 and 80 ~ C min -I . In the case of alloys with a lower Mg content (x ~< 0.5 at %) only the dissolution of GP zones could be observed during the heating, whereas in the case of alloys with a higher Mg content the formation of the ~?'-phase started before the total dissolution of GP zones and at higher temperatures the formation of the r/-phase also took place. These phases were identified by transmission electron microscopy. The heat-of-solution of GP zones shows saturation as a function of RT aging time. The time needed for the saturation increased monotonously with increasing Mg content. The reversion of zones was followed by in situ X-ray small angle scattering measurements. The change of the total scattered intensity was measured during continuous heating at a rate of 40 ~ C min -1 . These investigations have confirmed the results of the calorimetric measurements which indicate that the total dissolution of zones takes place only in the case of the alloys with a Mg content lower than 0.5 at%. In the case of alloys with a Zn concentration of 4.5 at % studied here, 1 at % Mg is sufficient to initiate the formation of more stable phases during the reversion of zones.

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Section: Resultssupporting

confidence: 88%

“…In their calorimetric investigations on the alloy with 0.012 at % Mg, besides the peak related to the dissolution of the Zn zones in the binary alloy, another peak characteristic only of the ternary alloy also appeared. Ohta and Hishimoto [18] and Tomita etal. [19] have also confirmed the co-existence of two types of zones in such alloys.…”

Section: Introductionmentioning

confidence: 96%

The influence of Mg content on the formation and reversion of Guinier-Preston zones in Al-4.5 at % Zn-x Mg alloys

et al. 1981

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“…The GP(I) zones contain both magnesium and zinc [34][35][36][37][38][39][40] that form partly as a result of the small size of the zinc atom number of spherical and ellipsoidal GP zones after aging at 75 ЊC. This means the zones present in the as-quenched (relative to aluminum) being compensated by the large size of the magnesium atom.…”

Section: Processes During Artificial Agingmentioning

confidence: 99%

Differential scanning calorimetry and electron diffraction investigation on low-temperature aging in Al-Zn-Mg alloys

Jiang

Taftø

Noble

et al. 2000

Metall Mater Trans A

135

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Differential scanning calorimetry (DSC) has been combined with transmission electron microscopy (TEM) to investigate the low-temperature decomposition processes taking place in an Al-5 wt pct Zn-1 wt pct Mg alloy. It was confirmed that two types of GP zones, i.e., GP(I) (solute-rich clusters) and GP(II) (vacancy-rich clusters), formed independently during decomposition of the supersaturated solid solution. The GP(I) zones form at a relatively low aging temperature and dissolve when the aging temperature is increased. The GP(II) zones are stable over a wider range of temperatures. To investigate the nature of the zones in the Al-Zn-Mg alloy, differential scanning calorimetry and transmission electron microscopy have also been carried out on binary Al-Zn alloys containing 5 wt pct and 10 wt pct Zn. In these Al-Zn alloys, GP zones formed rapidly during quenching, and they gave rise to characteristic electron diffraction patterns identical to those from GP(II) in the Al-ZnMg alloy system, implying that GP(II) zones in Al-Zn-Mg alloys are very similar to the zones formed in binary Al-Zn alloys. Thus, it is likely that GP(II) zones in Al-Zn-Mg alloys are zinc-rich clusters. In the Al-5 wt pct Zn-1 wt pct Mg alloy, both GP(I) and GP(II) were found to transform to Ј and/ or particles during heating in the differential scanning calorimeter. The Ј was also observed to form after prolonged isothermal aging of the Al-Zn-Mg alloy at 75 ЊC or after short aging times at 125 ЊC.

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“…Xexpl A kT 2 n (19) Some of the values of the critical temperatures T 2V *, T Vi * t and T 2V -i* are given in Table III for the case of aluminum. These critical temperatures are also plotted in Fig.…”

Section: Time During Quenching (In Msec)mentioning

confidence: 99%

Quenching of Metals Containing Impurity. I. Face-Centered-Cubic Metals

Doyama

1966

Phys. Rev.

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General kinetic equations between vacancies, divacancies, and impurity atoms are presented. Some applications of these equations to the reactions during quenching are treated. The critical temperatures or freezing temperatures which determine the status after the quench are also given. The treatment shows that the cooling rate near the critical temperature is important, and these temperatures are rather low in usual cases. The treatment is in good agreement with the results of the actual change during quenching calculated by a digital computer. A relation between the binding energy Bv% of an impurity atom and a vacancy and the solubility limit CL of the impurity is presented. A relation between the binding energy and the heat of solution H is also discussed. The tentative relation is B V i = 0.52#= (-0.088 logCz,+0.088) eV.

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Effect of Magnesium on the Clustering in Al-Zn-Mg Alloys

Cited by 18 publications

References 2 publications

The influence of Mg content on the formation and reversion of Guinier-Preston zones in Al-4.5 at % Zn-x Mg alloys

The influence of Mg content on the formation and reversion of Guinier-Preston zones in Al-4.5 at % Zn-x Mg alloys

Differential scanning calorimetry and electron diffraction investigation on low-temperature aging in Al-Zn-Mg alloys

Quenching of Metals Containing Impurity. I. Face-Centered-Cubic Metals

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