Interaction between a Vacancy and a Cd or In Atom in Al-10 wt% Zn Alloys

Ohta, Mutsuo; Hashimoto, Fumio

doi:10.1143/jpsj.19.1987

Cited by 21 publications

(5 citation statements)

References 5 publications

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“…We note that Hashimoto and Ohta [14,15] measured the solute-h binding for several solutes relative to that of Zn by examining the kinetic response of Al-Zn alloys to aging with and without the solute atoms present. Although these types of non-equilibrium experiments may contain sources of error for the precise quantitative values of the binding energy, one should still be able to compare the trends in binding between various solutes.…”

Section: Solute-vacancy Binding Of Microalloying Additions Tomentioning

confidence: 99%

Solute–vacancy binding in aluminum

2007

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Previous efforts to understand solute-vacancy binding in aluminum alloys have been hampered by a scarcity of reliable, quantitative experimental measurements. Here, we report a large database of solute-vacancy binding energies determined from first-principles density functional calculations. The calculated binding energies agree well with accurate measurements where available, and provide an accurate predictor of solute-vacancy binding in other systems. We find: (i) some common solutes in commercial Al alloys (e.g., Cu and Mg) possess either very weak (Cu), or even repulsive (Mg), binding energies. Hence, we assert that some previously reported large binding energies for these solutes are erroneous. (ii) Large binding energies are found for Sn, Cd and In, confirming the proposed mechanism for the reduced natural aging in Al-Cu alloys containing microalloying additions of these solutes. (iii) In addition, we predict that similar reduction in natural aging should occur with additions of Si, Ge and Au. (iv) Even larger binding energies are found for other solutes (e.g., Pb, Bi, Sr, Ba), but these solutes possess essentially no solubility in Al. (v) We have explored the physical effects controlling solute-vacancy binding in Al. We find that there is a strong correlation between binding energy and solute size, with larger solute atoms possessing a stronger binding with vacancies. (vi) Most transition-metal 3d solutes do not bind strongly with vacancies, and some are even energetically strongly repelled from vacancies, particularly for the early 3d solutes, Ti and V.

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Section: Solute-vacancy Binding Of Microalloying Additions Tomentioning

confidence: 99%

Solute–vacancy binding in aluminum

2007

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“…Positive correlation between the solute and vacancy binding energy and the solute size is well documented for dilute Al alloys 17, 18. A large impurity atom placed into the matrix imposes a significant strain on the surrounding atoms.…”

Section: Resultsmentioning

confidence: 97%

“…Such inward relaxation of the impurity towards the vacancy releases the strain imposed on the neighboring atoms and causes an energy decrease 17. However, the solute size effect alone cannot explain very small or even negative vacancy binding energies to 3d transition‐metal solutes 17 that are explained by formation of strong bonds between 3d transition metals and Al atoms 18. In analogy with Al alloys one could expect attractive interaction between vacancies and Gd or Tb solutes having larger size than Mg atoms.…”

Section: Resultsmentioning

confidence: 99%

Natural aging of Mg–Gd and Mg–Tb alloys

Čı́žek

Smola

Stulı́ková

et al. 2012

Physica Status Solidi (a)

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Substantial natural aging occurring on the time scale of less than 1 month was observed in solution‐treated Mg–Gd and Mg–Tb alloys. Solution treatment at 500 and 530 °C for Mg–Gd and Mg–Tb alloys, respectively, leads to dissolution of Gd or Tb in the Mg matrix. By quenching of solution‐treated alloys to room temperature a supersaturated solid solution of Gd or Tb in Mg was formed. During subsequent aging at ambient temperature the hardness of quenched alloys increases, most probably, due to agglomeration of dissolved Gd or Tb atoms into small clusters. Positron lifetime spectroscopy combined with coincident Doppler broadening revealed that quenched alloys contain vacancies bound to Gd or Tb atoms. Quenched‐in vacancies facilitate clustering of Gd or Tb solutes and disappear from the samples when the clusters are fully developed.

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“…In Mg alloys an attractive interaction likely exists between vacancies and Gd or Tb solutes having a larger size than Mg atoms. Positive correlation between the solute -vacancy binding energy and the solute size is well documented for dilute Al alloys [18,19]. A large impurity atom placed into the matrix imposes a significant strain on the surrounding atoms.…”

Section: Solution Treated Alloysmentioning

confidence: 97%

“…Hence, supersaturated solid solution of Gd or Tb in Mg can be obtained by rapid quenching from elevated temperatures. With increasing temperature the supersaturated solid solution α' decomposes obeying the following sequences [2]: Mg-Gd: α' (hcp) → β'' (D0 19 ) → β' (c-bco) → β (fcc, Mg 5 Gd).…”

Section: Introductionmentioning

confidence: 99%

Diffusion Processes in Early Stages of Precipitation in Mg-Gd and Mg-Tb Alloys

Melikhova

Čı́žek

Hruška

et al. 2013

DDF

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Early stages of precipitation were investigated in solution treated binary Mg-Tb and Mg-Gd alloys. The supersaturated solid solution of Gd (or Tb) in Mg was formed by fast quenching of the alloys from solution treatment temperature. Decomposition of the supersaturated solid solution and precipitation effects were investigated by positron lifetime spectroscopy combined with microhardness testing. During solution treatment at elevated temperature some thermal vacancies form pairs with solute atoms. In quenched samples free vacancies are quickly annealed out, while more stable vacancies bound to solute atoms remain in the sample and enhance the diffusivity of solutes. The hardness of solution treated Mg-Tb and Mg-Gd alloys aged at ambient temperature rises due to formation of small clusters of Tb and Gd atoms. Isochronal annealing of Mg-Tb and Mg-Gd alloys leads to precipitation of coherent β phase, semicoherent β phase and incoherent β phase particles. It was found that natural aging of Mg-Tb alloy at ambient temperature has beneficial effect on subsequent hardening by β phase particles formed during annealing.

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Interaction between a Vacancy and a Cd or In Atom in Al-10 wt% Zn Alloys

Cited by 21 publications

References 5 publications

Solute–vacancy binding in aluminum

Solute–vacancy binding in aluminum

Natural aging of Mg–Gd and Mg–Tb alloys

Diffusion Processes in Early Stages of Precipitation in Mg-Gd and Mg-Tb Alloys

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