Atomic structure of pre-Guinier-Preston and Guinier-Preston-Bagaryatsky zones in Al-alloys

Staab, T.E.M.; Klobes, Benedikt; Kohlbach, Iris; Korff, Björn; Haaks, M.; Dudzik, E.; Maier, K.

doi:10.1088/1742-6596/265/1/012018

Cited by 12 publications

(13 citation statements)

References 37 publications

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“…This conclusion is supported by the calculations of Staab et al 26 and by the fact that the same positron annihilation characteristics occur as for the reference sample after annealing at 193 C for 1 h (see Sec. III B).…”

Section: Isochronal Annealingsupporting

confidence: 71%

“…This lifetime is higher than the positron lifetime in bulk aluminium (s b $ 165 ps), but lower than the lifetime of positron trapped at aluminium vacancies (s v $ 246 ps) 25 or vacancy-copper complexes (s v-Cu $ 229-206 ps, depending on cooper environment). 26 This lifetime of $196 ps is often found in as quenched samples 12,[21][22][23] and is most likely a mixed lifetime of different vacancy-copper complexes with lifetimes reported as $205 ps 12,13,24,26,27 and 178 ps (found by Ferragut et al 22 after short heat treatment at 150 C for 1 min). The formation of Guinier-Preston zones in the quenched sample is possible but cannot be confirmed by the measurement results.…”

Section: A Initial State After Quenchingmentioning

confidence: 83%

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Microstructure and vacancy-type defects of high-pressure torsion deformed Al-3 wt%Cu alloy

Parz

Faller

Pippan

et al. 2012

Journal of Applied Physics

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The influence of high-pressure torsion (HPT) on the microstructure and free-volume type defects of supersaturated Al-3 wt%Cu was studied. By means of HPT, grain refinement down to sizes of 100 nm could be achieved. Positron annihilation spectroscopy was applied for the characterization of deformation-induced defects and of vacancy-solute interaction. The chemical sensitive method of two-dimensional Doppler broadening spectroscopy reveals predominantly deformation-induced defects. In comparison to undeformed supersaturated Al-3 wt%Cu, the fraction of Cu-decorated free-volume type defects is strongly reduced and Al2Cu-precipitates with equilibrium structure occur rather than metastable semi-coherent Al-Cu precipitates. These precipitates stabilize the nanocrystalline structure and give rise to a rather different aging behaviour compared to the undeformed state.

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Section: Isochronal Annealingsupporting

confidence: 71%

Section: A Initial State After Quenchingmentioning

confidence: 83%

Microstructure and vacancy-type defects of high-pressure torsion deformed Al-3 wt%Cu alloy

Parz

Faller

Pippan

et al. 2012

Journal of Applied Physics

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“…To assist with the interpretation of these results the following information from the literature is required. Wellannealed Al has a positron lifetime of approximately 162-168ps [67][68][69] . Quenched-in vacancies increase positron lifetime considerably and there is a decay in positron lifetime after quenching until the equilibrium vacancy contribution is reached 22,44 .…”

Section: Characterization By Positron Annihilation Lifetime Spectroscopy (Pals)mentioning

confidence: 99%

Quench Sensitivity in a Dispersoid-Containing Al-Mg-Si Alloy

Strobel¹,

Easton

Lay³

et al. 2019

Metall Mater Trans A

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The quench sensitivity of a 6xxx series alloy with a high content of dispersoids was studied over a wide range of cooling rate and natural aging time. Positron annihilation lifetime spectroscopy (PALS), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) were used to characterize the clustering and precipitation reactions. The alloy showed significant quench sensitivity after short natural aging (2 min and 30 min), but the quench sensitivity was lower after long natural aging (24 h). The quench sensitivity after the long natural aging can be accounted for by solute loss due to the formation of non-hardening β' precipitates on the dispersoids during cooling from solution treatment. For short natural aging, however, quenched-in vacancies and modifications to the precipitation sequence also have substantial contributions to the quench sensitivity. This work provides new insight into the quench sensitivity of 6xxx series alloys that contain a high dispersoid density.

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“…4,5,7,[15][16][17] On the other hand, the detailed atomistic level insight from theoretical studies may provide useful information for synthesizing alloys in experiments with boosted specific properties. 14,[18][19][20][21] Prominent examples can be found in aluminium alloys that play increasingly crucial roles in various industrial products. 5,[8][9][10][11][12][22][23][24][25] One of the main goals of alloying matrices is to obtain the most lightweight and high-strength alloys that can be extensively used in aircraft industries, modern trains and vehicles, and so forth.…”

Section: Introductionmentioning

confidence: 99%

Density functional simulations of pressurized Mg-Zn and Al-Zn alloys

Alidoust

Kleiven

Akola

2020

Phys. Rev. Materials

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The Mg-Zn and Al-Zn binary alloys have been investigated theoretically under static isotropic pressure. The stable phases of these binaries on both initially hexagonal-close-packed (HCP) and face-centered-cubic (FCC) lattices have been determined by utilizing an iterative approach that uses a configurational cluster expansion method, Monte Carlo search algorithm, and density functional theory (DFT) calculations. Based on 64-atom models, it is shown that the most stable phases of the Mg-Zn binary alloy under ambient condition are MgZn 3 , Mg 19 Zn 45 , MgZn, and Mg 34 Zn 30 for the HCP, and MgZn 3 and MgZn for the FCC lattice, whereas the Al-Zn binary is energetically unfavorable throughout the entire composition range for both the HCP and FCC lattices under all conditions. By applying an isotropic pressure in the HCP lattice, Mg 19 Zn 45 turns into an unstable phase at P≈10 GPa, a new stable phase Mg 3 Zn appears at P 20 GPa, and Mg 34 Zn 30 becomes unstable for P 30 GPa. For FCC lattice, the Mg 3 Zn phase weakly touches the convex hull at P 20 GPa while the other stable phases remain intact up to ≈120 GPa. Furthermore, making use of the obtained DFT results, bulk modulus has been computed for several compositions up to pressure values of the order of ≈120 GPa. The findings suggest that one can switch between Mg-rich and Zn-rich early-stage clusters simply by applying external pressure. Zn-rich alloys and precipitates are more favorable in terms of stiffness and stability against external deformation.

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Atomic structure of pre-Guinier-Preston and Guinier-Preston-Bagaryatsky zones in Al-alloys

Cited by 12 publications

References 37 publications

Microstructure and vacancy-type defects of high-pressure torsion deformed Al-3 wt%Cu alloy

Microstructure and vacancy-type defects of high-pressure torsion deformed Al-3 wt%Cu alloy

Quench Sensitivity in a Dispersoid-Containing Al-Mg-Si Alloy

Density functional simulations of pressurized Mg-Zn and Al-Zn alloys

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