Diffusion coefficients of some solutes in fcc and liquid Al: critical evaluation and correlation

Du, Yong; Chang, Y. A.; Huang, Baiyun; Gong, Weiping; Jin, Zhanpeng; Xu, Honghui; Yuan, Zhaonian; Liu, Yong; He, Yuehui; Xie, Fanyou

doi:10.1016/s0921-5093(03)00624-5

Cited by 757 publications

(225 citation statements)

References 46 publications

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“…It is noted also that the activation energy of Zn/Mg GPZ dissolution is close to that for migration of Mg and Zn in Al, i.e., around 1.14 to 1.35 and 1.22 eV per atom, respectively. [49] Summarizing, the models proposed by Papazian apparently lead to a slight underestimation of the activation energy for both AA 7075 and AA 2024. Hence, the reaction rate proposed by Jena (Eq.…”

Section: Discussionmentioning

confidence: 93%

“…Papazian [20] affirmed that the activation energy for Cu GPZ dissolution should be close to that for chemical interdiffusion in the AlCu systems, which is around 1.24 to 1.47 eV per atom. [20,49] While the values obtained for AA 2024 using Papazian's rate expressions (Eq. [2] and [3]) are not far from this range, the activation energy obtained when using Jena's rate equation Eq.…”

Section: Discussionmentioning

confidence: 99%

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Modeling of the Effect of Temperature, Frequency, and Phase Transformations on the Viscoelastic Properties of AA 7075-T6 and AA 2024-T3 Aluminum Alloys

Rojas

Crespo

2012

Metall Mater Trans A

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The viscoelastic response of commercial aluminum alloys 7075-T6 and 2024-T3 as a function of temperature is presented. Experimental data are obtained with a dynamic-mechanical analyzer (DMA) at different loading frequencies and compared with the available transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) data. The effect of successive microstructural transformations (particle precipitation and redissolution) is revealed. An analytical model is developed, which fits the mechanical response up to 573 K (300°C). The model takes into account the concentration of Guinier-Preston Zones (GPZ) and metastable precipitates (g¢ in AA 7075-T6 and h¢/S¢ in AA 2024-T3), allowing us to determine the kinetic parameters of these transformations. The activation energies were previously obtained by several authors from DSC measurements and other techniques, showing considerable dispersion. The presented data, obtained with a completely different technique, allow us to reduce the uncertainty on these data and show the potential of DMA measurements in the study of microstructural transformations.

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Modeling of the Effect of Temperature, Frequency, and Phase Transformations on the Viscoelastic Properties of AA 7075-T6 and AA 2024-T3 Aluminum Alloys

Rojas

Crespo

2012

Metall Mater Trans A

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“…However, the diffusion rate of Mn rapidly increases with temperature [17,30]. Hence, EC increases with increasing temperature when treated for the same duration, and the time to reach the peak of EC decreases with increasing temperature (Fig.…”

Section: Evolution Of Properties During Precipitation Treatmentmentioning

confidence: 91%

Development of Al–Mn–Mg 3004 alloy for applications at elevated temperature via dispersoid strengthening

2015

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In this study, the potential applications of Al-Mn-Mg 3004 alloy at elevated temperature have been evaluated through the systematic study of the precipitation behavior of α-Al(MnFe)Si dispersoids and their effect on material properties during precipitation treatment and long-term thermal holding. The results demonstrate a significant dispersion strengthening effect caused by the precipitation of fine uniformly distributed dispersoids during precipitation treatment. The peak compression yield strength (YS) at 300°C of the experimental 3004 alloy can reach as high as 78 MPa due to a large volume fraction (~2.95 vol. %) of α-Al(MnFe)Si dispersoids. The dispersoids are found to be thermally stable at 300°C for up to 1000 h of holding, leading to consistently high mechanical performance and creep resistance. The superior and stable YS and creep resistance at 300°C enables the 3004 alloy to be applied to weight-sensitive applications at elevated temperatures.

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“…The apparent activation energies for diffusion of BFRs (96−154 kJ· mol −1 ) in the plastic matrices were smaller than the activation energies reported for diffusion of Cr, Mn, and Fe in fcc Al (186−221 kJ·mol −1 ), but greater than those of Fe, Co, Ni, Cu, and Ga diffusion in liquid Al (20−34 kJ·mol −1 ). 42 Although the BFR molecules are expected to interact with the polymers of the plastic matrices primarily through van der Waals force and hydrogen bonding, the rather high activation energies for their diffusion probably result from the significant steric hindrance exerted on them by the tight polymer chains, which may necessitate bending or stretching of certain chemical bonds.…”

Section: Environmental Science and Technologymentioning

confidence: 99%

Kinetics of Brominated Flame Retardant (BFR) Releases from Granules of Waste Plastics

Sun

Cheng

et al. 2016

Environ. Sci. Technol.

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Plastic components of e-waste contain high levels of brominated flame retardants (BFRs), whose releases cause environmental and human health concerns. This study characterized the release kinetics of polybrominated diphenyl ethers (PBDEs) from millimeter-sized granules processed from the plastic exteriors of two scrap computer displays at environmentally relevant temperatures. The release rate of a substitute of PBDEs, 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), from the waste plastics, was reported for the first time. Deca-BDE was the most abundant PBDE congeners in both materials (87−89%), while BTBPE was also present at relatively high contents. The release kinetics of BFRs could be modeled as one-dimensional diffusion, while the temperature dependence of diffusion coefficients was well described by the Arrhenius equation. The diffusion coefficients of BFRs (at 30°C) in the plastic matrices were estimated to be in the range of 10 −27.16 to 10 −19.96 m 2 ·s −1 , with apparent activation energies between 88.4 and 154.2 kJ·mol −1 . The half-lives of BFR releases (i.e., 50% depletion) from the plastic granules ranged from thousands to tens of billions of years at ambient temperatures. These findings suggest that BFRs are released very slowly from the matrices of waste plastics through molecular diffusion, while their emissions can be significantly enhanced with wear-and-tear and pulverization.

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Diffusion coefficients of some solutes in fcc and liquid Al: critical evaluation and correlation

Cited by 757 publications

References 46 publications

Modeling of the Effect of Temperature, Frequency, and Phase Transformations on the Viscoelastic Properties of AA 7075-T6 and AA 2024-T3 Aluminum Alloys

Modeling of the Effect of Temperature, Frequency, and Phase Transformations on the Viscoelastic Properties of AA 7075-T6 and AA 2024-T3 Aluminum Alloys

Development of Al–Mn–Mg 3004 alloy for applications at elevated temperature via dispersoid strengthening

Kinetics of Brominated Flame Retardant (BFR) Releases from Granules of Waste Plastics

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