Kinetics and mechanisms of precipitation in an Al–0.2wt.% Sc alloy

Røyset, Jostein; Ryum, N.

doi:10.1016/j.msea.2005.02.015

Cited by 139 publications

(81 citation statements)

References 41 publications

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“…This value is close to 1.5 which corresponds to the idealized case in which all precipitates nucleate simultaneously at random sites. 12) Values of n for the rapid stage in Al-Sc alloys have already been reported in other investigations: 5,13) the reported n values are in the range 1.1 to 2.0 at temperatures between 503 and 743 K. In the middle and slow stages in Fig. 5, n is derived as ð0:31 AE 0:03Þ and ð0:076 AE 0:008Þ, respectively.…”

Section: Kinetics Of Precipitationsupporting

confidence: 63%

Coarsening Kinetics of Al<SUB>3</SUB>Sc Precipitates in an Al–Mg–Sc Alloy Aged at 573 K

Watanabe

Monzen

2007

Mater. Trans.

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The coarsening of Al 3 Sc precipitates in an Al-1 mass%Mg-0.27 mass%Sc alloy aged at 573 K has been examined using a model developed by Kuehmann and Voorhees. The average size of Al 3 Sc precipitates was evaluated by transmission electron microscopy and electrical resistivity was employed to measure the Sc concentration in the matrix. Kinetic analyses revealed that before the onset of a coarsening stage, there exist mixed stages of nucleation and growth and of growth and coarsening. The coherent Al/Al 3 Sc interface energy is estimated as 0.23 Jm À2 from data on coarsening alone. The transition from a coherent interface to a semi-coherent interface caused no change in .

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Section: Kinetics Of Precipitationsupporting

confidence: 63%

Coarsening Kinetics of Al<SUB>3</SUB>Sc Precipitates in an Al–Mg–Sc Alloy Aged at 573 K

Watanabe

Monzen

2007

Mater. Trans.

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“…pct Zr alloys during isochronal aging, during which a significant increase in electrical conductivity is observed to accompany precipitation of Al 3 Zr. Moreover, Royset and Ryum [56] recently monitored in detail the decomposition kinetics of dilute Al-0.12 at. pct Sc alloys using a similar eddy current apparatus, indicating that the technique is sensitive enough to detect precipitation of Al 3 M in dilute alloys.…”

Section: Electrical Conductivitymentioning

confidence: 99%

Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

Knipling

Dunand

Seidman

2007

Metall Mater Trans A

181

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Two conventionally solidified Al-0.2Ti alloys (with 0.18 and 0.22 at. pct Ti) exhibit no hardening after aging up to 3200 hours at 375°C or 425°C. This is due to the absence of Al 3 Ti precipitation, as confirmed by electron microscopy and electrical conductivity measurements. By contrast, an Al-0.2Zr alloy (with 0.19 at. pct Zr) displays strong age hardening at both temperatures due to precipitation of Al 3 Zr (L1 2 ) within Zr-enriched dendritic regions. This discrepancy between the two alloys is explained within the context of the equilibrium phase diagrams: (1) the disparity in solid and liquid solubilities of Ti in a-Al is much greater than that of Zr in a-Al; and (2) the relatively small liquid solubility of Ti in a-Al limits the amount of solute retained in solid solution during solidification, while the comparatively high solid solubility reduces the supersaturation effecting precipitation during post-solidification aging. The lattice parameter mismatch of Al 3 Ti (L1 2 ) with a-Al is also larger than that of Al 3 Zr (L1 2 ), further hindering nucleation of Al 3 Ti. Classical nucleation theory indicates that the minimum solute supersaturation required to overcome the elastic strain energy of Al 3 Ti nuclei cannot be obtained during conventional solidification of Al-Ti alloys (unlike for Al-Zr alloys), thus explaining the absence of Al 3 Ti precipitation and the presence of Al 3 Zr precipitation.

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“…Except for Jo and Fujikawa's data [6] for which only a poor agreement could be obtained, cluster dynamics manage to reproduce reasonably well experimental measurements of electrical resistivity [8][9][10]. For the highest annealing temperatures corresponding to the lowest supersaturations, a time shift could appear between the simulated and the experimental resistivity, the time evolution predicted by cluster dynamics being too fast.…”

Section: Discussionmentioning

confidence: 80%

“…2 in Ref. 10). Nevertheless we find that the value measured by Fujikawa et al [6,21] is the one that leads to the best agreement between the simulated and the experimental resistivity variations during precipitation kinetics.…”

Section: Cluster Contribution To Electrical Resistivitymentioning

confidence: 91%

“…Røyset and Ryum [10] used their resistivity measurements to follow the Sc transformed fraction. In their treatment, they estimated the equilibrium solid solution from extrapolation of resistivity measurements in the coarsening stage 4 They actually measured by EDS analysis a slightly higher composition, x 0 Sc = 0.138 at.%, but cluster dynamics simulations obtained with this measured concentration do not significantly differ from those obtained with the nominal composition.…”

Section: Al -012 At% Scmentioning

confidence: 99%

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Using cluster dynamics to model electrical resistivity measurements in precipitating AlSc alloys

Clouet

Barbu

2007

Acta Materialia

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Electrical resistivity evolution during precipitation in Al-Sc alloys is modeled using cluster dynamics. This mesoscopic modeling has already been shown to correctly predict the time evolution of the precipitate size distribution. In this work, we show that it leads too to resistivity predictions in quantitative agreement with experimental data. We only assume that all clusters contribute to the resistivity and that each cluster contribution is proportional to its area. One interesting result is that the resistivity excess observed during coarsening mainly arises from large clusters and not really from the solid solution. As a consequence, one cannot assume that resistivity asymptotic behavior obeys a simple power law as predicted by LSW theory for the solid solution supersaturation. This forbids any derivation of the precipitate interface free energy or of the solute diffusion coefficient from resistivity experimental data in a phase-separating system like Al-Sc supersaturated alloys.

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Kinetics and mechanisms of precipitation in an Al–0.2wt.% Sc alloy

Cited by 139 publications

References 41 publications

Coarsening Kinetics of Al<SUB>3</SUB>Sc Precipitates in an Al–Mg–Sc Alloy Aged at 573 K

Coarsening Kinetics of Al<SUB>3</SUB>Sc Precipitates in an Al–Mg–Sc Alloy Aged at 573 K

Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

Using cluster dynamics to model electrical resistivity measurements in precipitating AlSc alloys

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Kinetics and mechanisms of precipitation in an Al–0.2wt.% Sc alloy

Cited by 139 publications

References 41 publications

Coarsening Kinetics of Al<SUB>3</SUB>Sc Precipitates in an Al&ndash;Mg&ndash;Sc Alloy Aged at 573 K

Coarsening Kinetics of Al<SUB>3</SUB>Sc Precipitates in an Al&ndash;Mg&ndash;Sc Alloy Aged at 573 K

Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

Using cluster dynamics to model electrical resistivity measurements in precipitating AlSc alloys

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Product

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Coarsening Kinetics of Al<SUB>3</SUB>Sc Precipitates in an Al–Mg–Sc Alloy Aged at 573 K

Coarsening Kinetics of Al<SUB>3</SUB>Sc Precipitates in an Al–Mg–Sc Alloy Aged at 573 K