The Diffusion Coefficient of Scandium in Dilute Aluminum-Scandium Alloys

Kerkove, Marcel A.; Wood, Thomas D.; Sanders, Paul G.; Kampe, S. L.; Swenson, D.

doi:10.1007/s11661-014-2275-4

Cited by 39 publications

(10 citation statements)

References 15 publications

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“…However, the diffusion coefficient of zirconium in aluminum [142] is much less than that of scandium in aluminum [143][144][145][146]. As a result, Al3Zr particles precipitate at higher temperatures and/or longer annealing times compared to Al3Sc particles.…”

Section: Discussionmentioning

confidence: 99%

Effect of Sc:Zr Ratio on Superplastic Behavior of Ultrafine-grained Al-6%Mg-Sc-Zr Alloys

Чувильдеев¹,

Gryaznov²,

Shotin³

et al. 2022

Preprint

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Al-6%Mg-Sc-Zr alloys with the total ratio of Sc + Zr = 0.32 wt.% make up the target of this research. The content of scandium and zirconium varied with an increment of 0.02%. The alloys were produced by induction casting. Their ultrafine-grained (UFG) microstructure was formed with Equal Channel Angular Pressing (ECAP). Such cast alloys have a homogeneous macrostructure formed by small equiaxed grains in the central part of the ingot and columnar crystals along the edges of the cross section. After ECAP, the average grain size in the alloy specimens is 0.5–1 µm. The average grain size does not depend on the ratio of Sc and Zr in these alloys. Superplasticity tests were performed at temperatures ranging from 300 to 500 °C and at a strain rate varying between 3.3·10-3 and 3.3·10-1 s-1. UFG Al-6%Mg-0.20%Sc-0.12%Zr and Al-6%Mg-0.18%Sc-0.14%Zr alloys exhibit the highest superplasticity. It was suggested that changes in Sc:Zr ratio affect spatial distribution and composition of the following precipitating particles: Al3Sc, Al3Zr, Al3(ScxZr1-x). An increase in Zr concentration is shown to reduce the susceptibility of UFG alloys to cavitation fracture.

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Section: Discussionmentioning

confidence: 99%

Effect of Sc:Zr Ratio on Superplastic Behavior of Ultrafine-grained Al-6%Mg-Sc-Zr Alloys

Чувильдеев¹,

Gryaznov²,

Shotin³

et al. 2022

Preprint

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“…As shown in [131][132][133], precipitating secondary Al3(Zr,Sc) particles in Al-Zr-Sc alloys have the following structure: Al3Sc core -Al3Zr shell. The diffusion coefficient of scandium in aluminum [134][135][136][137] is noticeably higher than the diffusion coefficient of zirconium in aluminum [138]. As a result, Al3Sc particles precipitate at lower temperatures or shorter heating times compared to Al3Zr particles.…”

Section: Discussionmentioning

confidence: 99%

Effect of Sc, Hf, and Yb Additions on Superplasticity of a Fine-grained Al-0.4%Zr Alloy

Нохрин¹,

Gryaznov²,

Shotin³

et al. 2022

Preprint

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The research was undertaken to study the way deformation behaves in ultrafine-grained (UFG) conducting Al-Zr alloys doped with Sc, Hf, and Yb. All in all, 8 alloys were studied with zirconium partially replaced by Sc, Hf, and/or Yb. Doping elements (X = Zr, Sc, Hf, Yb) in the alloys total 0.4 wt.%. The choice of doping elements is conditioned by possible precipitation of Al3X particles with L12 structure while annealing these alloys. Such particles provide higher thermal stability of a nonequilibrium UFG microstructure. Initial coarse-grained samples were obtained by induction casting. The UFG microstructure in the alloys was formed by Equal Channel Angular Pressing (ECAP) at 225°C. Superplasticity tests were carried out at temperatures ranging from 300 to 500 °C and strain rates varying between 3.310-4 and 3.310-1 s-1. The highest values of elongation to failure are observed in Sc-doped alloys. A UFG Al-0.2%Zr-0.1%Sc-0.1%Hf alloy has maximum ductility: at 450 °C and a strain rate of 3.310-3 s-1, relative elongation to failure reaches 765%. At the onset of superplasticity, stress–strain curves are characterized by a stage of homogeneous strain and a long stage of localized plastic flow. The dependence of homogeneous strain (eq) on test temperature in UFG Sc-doped alloys is increasing uniformly, which is not the case for other UFG alloys with eq(T) dependence peaking at 350-400 оС. Strain rate sensitivity coefficient of flow stress m is small and does not exceed 0.26-0.3 at 400-500 °C. In UFG alloys containing no scandium, m coefficient is observed to go down to 0.12-0.18 at 500 оС. It has been suggested that lower m values are driven by intensive grain growth and pore formation in large Al3X particles, which develop specifically at the ingot crystallization stage.

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“…The ultimate goal is to overcome the present knowledge and manufacturing barriers and develop aluminum alloys with superior properties that remain stable across the temperature and time space, required by modern designs. (*) results of combining measurements in [157,180] with literature data. [215] (1) supersaturated, cooling rate 10 3 −10 4 deg/s; (2) aluminum melting point-660.452 • C; (3) Type of the binary Al-X phase diagram: Eut-eutectic reaction, Per-peritectic reaction.…”

Section: Discussionmentioning

confidence: 99%

Thermal Stability of Aluminum Alloys

Czerwiński

2020

Materials

113

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Thermal stability, determining the material ability of retaining its properties at required temperatures over extended service time, is becoming the next frontier for aluminum alloys. Its improvement would substantially expand their range of structural applications, especially in automotive and aerospace industries. This report explains the fundamentals of thermal stability; definitions, the properties involved; and the deterioration indicators during thermal/thermomechanical exposures, including an impact of accidental fire, and testing techniques. For individual classes of alloys, efforts aimed at identifying factors stabilizing their microstructure at service temperatures are described. Particular attention is paid to attempts of increasing the current upper service limit of high-temperature grades. In addition to alloying aluminum with a variety of elements to create the thermally stable microstructure, in particular, transition and rare-earth metals, parallel efforts are explored through applying novel routes of alloy processing, such as rapid solidification, powder metallurgy and additive manufacturing, engineering alloys in a liquid state prior to casting, and post-casting treatments. The goal is to overcome the present barriers and to develop novel aluminum alloys with superior properties that are stable across the temperature and time space, required by modern designs.

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The Diffusion Coefficient of Scandium in Dilute Aluminum-Scandium Alloys

Cited by 39 publications

References 15 publications

Effect of Sc:Zr Ratio on Superplastic Behavior of Ultrafine-grained Al-6%Mg-Sc-Zr Alloys

Effect of Sc:Zr Ratio on Superplastic Behavior of Ultrafine-grained Al-6%Mg-Sc-Zr Alloys

Effect of Sc, Hf, and Yb Additions on Superplasticity of a Fine-grained Al-0.4%Zr Alloy

Thermal Stability of Aluminum Alloys

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