Quenching Studies of Lattice Vacancies in High-Purity Aluminium

Khellaf, A.; Seeger, A.; Emrick, Roy M.

doi:10.2320/matertrans.43.186

Cited by 31 publications

(23 citation statements)

References 58 publications

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“…The void volume fractions obtained by SAXS for the 4 N samples (Table 2) are an order of magnitude less than the theoretical supersaturated volume fractions. This result is consistent with the fact that a significant number of vacancies are lost by migration to sinks, such as self-interstitials, dislocations, grain boundaries and the surface during the quenching process [31], thereby serving as a consistency check of the indirect estimates of void volume fraction obtained in the SAXS study. Measured values of / can be used to determine the inter-void distance which plays a direct role in ductile failure of materials [43].…”

Section: Discussionsupporting

confidence: 80%

“…The coupons were then heated to the quench temperatures of 500, 550 or 600°C for 15 s before quenching in a water bath at 5°C. The quench and bath temperatures were chosen to optimize the thermally induced vacancy concentration; faster quench rates to lower bath temperatures have been shown to maximize the number of thermal vacancies while reducing vacancy agglomeration [31]. Consequently, the level of void scattering is expected to increase with increasing quench temperature and quench rate [29].…”

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confidence: 99%

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Nanovoid characterization of nominally pure aluminium using synchrotron small angle X-ray Scattering (SAXS) methods

Chaudhuri

Singh

Diak

et al. 2013

Philosophical Magazine

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A small angle X-ray scattering (SAXS) study of nanovoids in 99. 988 and 99.995 at.% aluminium is presented. Absolute intensity calibration using a glassy carbon standard is used to extract the weak SAXS signature from nanovoids introduced by thermal quenching. SAXS analysis methods, including Guinier, Porod and Indirect Transform, are used to obtain values for the void-size, number distribution and volume fraction, as well as measures of the void-metal matrix interface structure in quenched aluminium samples. The SAXS analysis has identified a residual impurity effect on void formation and has been used to characterize trends in nanovoid size, number distribution and interface structure as a function of ageing time at elevated temperatures (artificial ageing). The work presented here, including identification of experimental tools that can be readily improved, demonstrates that SAXS studies are capable of providing precise characterization of nanovoid structure in aluminium. This level of information will be useful in developing phenomenological models of void nucleation and growth capable of linking atomic scale phenomena to macroscopic material properties.

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Section: Discussionsupporting

confidence: 80%

mentioning

confidence: 99%

Nanovoid characterization of nominally pure aluminium using synchrotron small angle X-ray Scattering (SAXS) methods

Chaudhuri

Singh

Diak

et al. 2013

Philosophical Magazine

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show abstract

“…A drawback of the QH approach is that its accuracy is difficult to assess. Traditionally, anharmonic contributions beyond quasiharmonicity have been assumed to be small [7], most likely because accurate tools to compute them were missing. Only recent methodological advances, mainly based on thermodynamic integration techniques [8][9][10], allowed us to reduce the number of sampling configurations by 3-4 orders of magnitude providing, thereby, access to the numerically exact free-energy surface.…”

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confidence: 99%

Understanding Anharmonicity in fcc Materials: From its Origin toab initioStrategies beyond the Quasiharmonic Approximation

et al. 2015

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We derive the Gibbs energy including the anharmonic contribution due to phonon-phonon interactions for an extensive set of unary fcc metals (Al, Ag, Au, Cu, Ir, Ni, Pb, Pd, Pt, Rh) by combining density-functional-theory (DFT) calculations with efficient statistical sampling approaches. We show that the anharmonicity of the macroscopic system can be traced back to the anharmonicity in local pairwise interactions. Using this insight, we derive and benchmark a highly efficient approach which allows the computation of anharmonic contributions using a few T=0 K DFT calculations only.

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“…All values have been multiplied by the entropy factor − / =2 not included in MatCalc, the value of which is from Ref. [45]. Figure 11.…”

Section: Discussionmentioning

confidence: 99%

Microscopic Aspects of Artificial Ageing in Al-Mg-Si Alloys

Madanat

Zhang

et al. 2019

SSRN Journal

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Al-Mg-Si alloys with total solute contents ranging from 0.8 to 1.4 wt.% were solutionised, quenched and then artificially aged (AA) at 180 °C, after which positron annihilation lifetime spectroscopy was applied to obtain information about precipitation and vacancy evolution during preceding ageing.Hardness and electrical resistivity measurements were carried out to complement these measurements. AA was carried out in four different heating media, which allowed for varying the heating rate from 2.4 K·s -1 to 170 K·s -1 . The main result of the study is that there is a competition between vacancy losses and precipitation. Any precipitation taking place during quenching or during heating to the AA temperature helps to prevent vacancies from going to sinks and allows them to assist in solute clustering. Higher solute content, slower heating to 180 °C and natural pre-ageing before AA were found to have a comparable effect. Frequently used abbreviations SHTsolution heat treatment NA / NPA / NSA: natural ageing / natural pre-ageing / natural secondary ageing AA artificial ageing LM liquid metal MS molten salt

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Quenching Studies of Lattice Vacancies in High-Purity Aluminium

Cited by 31 publications

References 58 publications

Nanovoid characterization of nominally pure aluminium using synchrotron small angle X-ray Scattering (SAXS) methods

Nanovoid characterization of nominally pure aluminium using synchrotron small angle X-ray Scattering (SAXS) methods

Understanding Anharmonicity in fcc Materials: From its Origin toab initioStrategies beyond the Quasiharmonic Approximation

Microscopic Aspects of Artificial Ageing in Al-Mg-Si Alloys

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