Coarsening resistance at 400 °c of precipitation-strengthened Al-Zr-Sc-Er alloys

Christopher Booth-Morrison; David C. Dunand; David N. Seidman

doi:10.1016/j.actamat.2011.07.057

Coarsening resistance at 400 °c of precipitation-strengthened Al-Zr-Sc-Er alloys

Christopher Booth-Morrison^*, David C. Dunand, David N. Seidman

^*Corresponding author for this work

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

414 Scopus citations

Abstract

The effect of substituting 0.01 or 0.02 at.% Er for Sc in an Al-0.06 Zr-0.06 Sc at.% alloy was studied to develop cost-effective high-temperature aluminum alloys for aerospace and automotive applications. Spheroidal, coherent, L1 ₂-ordered Al ₃(Sc, Zr, Er) precipitates with a structure consisting of an Er-enriched core surrounded by a Sc-enriched inner shell and a Zr-enriched outer shell (core/double-shell structure) were formed after aging at 400 °C. This core/double-shell structure strengthens the alloy, and renders it coarsening resistant for at least 64 days at 400 °C. This structure is formed due to sequential precipitation of solute elements according to their diffusivities, D, where D _Er > D _Sc > D _Zr at 400 °C. Zr and Er are effective replacements for Sc, accounting for 33 ± 1% of the total precipitate solute content in an Al-0.06 Zr-0.04 Sc-0.02 Er at.% alloy aged at 400 °C for 64 days. Er accelerates precipitation kinetics at 400 °C, resulting in: (i) strengthening due to the elimination of lobed-cuboidal precipitates in favor of spheroidal precipitates; and (ii) a decrease in the incubation time for nucleation because D _Er > D _Sc. Finally, a two-stage aging treatment (24 h at 300 °C + 8 h at 400 °C) provides peak microhardness due to optimization of the nanostructure.

Original language	English (US)
Pages (from-to)	7029-7042
Number of pages	14
Journal	Acta Materialia
Volume	59
Issue number	18
DOIs	https://doi.org/10.1016/j.actamat.2011.07.057
State	Published - Oct 2011

Funding

This research was sponsored by the Ford-Boeing-Northwestern University Alliance (81132882). Atom-probe tomographic measurements were performed at the Northwestern University Center for Atom-probe Tomography (NUCAPT). The LEAP tomography system was purchased and upgraded with funding from NSF-MRI (DMR-0420532) and ONR-DURIP (N00014-0400798, N00014-0610539, and N00014-0910781) Grants. We thank M. Krug (NU) for his assistance with casting, TEM and many useful discussions, A. Hunter (NU) and M. Diaz (NU) for their assistance with SEM and Dr. D. Isheim for his assistance with LEAP tomography. We thank Dr. K. Knipling (Naval Research Laboratory) for his suggestions regarding casting and heat treatment, Prof. C. Wolverton (NU) and Dr. Z. Mao (NU) for sharing the results of their first-principles calculations, and Dr. J. Boileau (Ford), Dr. B. Ghaffari (Ford) and Mr. C. Huskamp (Boeing) for numerous useful discussions.

Keywords

Aluminum alloys
Erbium
Precipitation
Scandium
Zirconium

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Ceramics and Composites
Polymers and Plastics
Metals and Alloys

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10.1016/j.actamat.2011.07.057

Cite this

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title = "Coarsening resistance at 400 °c of precipitation-strengthened Al-Zr-Sc-Er alloys",

abstract = "The effect of substituting 0.01 or 0.02 at.% Er for Sc in an Al-0.06 Zr-0.06 Sc at.% alloy was studied to develop cost-effective high-temperature aluminum alloys for aerospace and automotive applications. Spheroidal, coherent, L1 2-ordered Al 3(Sc, Zr, Er) precipitates with a structure consisting of an Er-enriched core surrounded by a Sc-enriched inner shell and a Zr-enriched outer shell (core/double-shell structure) were formed after aging at 400 °C. This core/double-shell structure strengthens the alloy, and renders it coarsening resistant for at least 64 days at 400 °C. This structure is formed due to sequential precipitation of solute elements according to their diffusivities, D, where D Er > D Sc > D Zr at 400 °C. Zr and Er are effective replacements for Sc, accounting for 33 ± 1% of the total precipitate solute content in an Al-0.06 Zr-0.04 Sc-0.02 Er at.% alloy aged at 400 °C for 64 days. Er accelerates precipitation kinetics at 400 °C, resulting in: (i) strengthening due to the elimination of lobed-cuboidal precipitates in favor of spheroidal precipitates; and (ii) a decrease in the incubation time for nucleation because D Er > D Sc. Finally, a two-stage aging treatment (24 h at 300 °C + 8 h at 400 °C) provides peak microhardness due to optimization of the nanostructure.",

keywords = "Aluminum alloys, Erbium, Precipitation, Scandium, Zirconium",

author = "Christopher Booth-Morrison and Dunand, {David C.} and Seidman, {David N.}",

note = "Funding Information: This research was sponsored by the Ford-Boeing-Northwestern University Alliance (81132882). Atom-probe tomographic measurements were performed at the Northwestern University Center for Atom-probe Tomography (NUCAPT). The LEAP tomography system was purchased and upgraded with funding from NSF-MRI (DMR-0420532) and ONR-DURIP (N00014-0400798, N00014-0610539, and N00014-0910781) Grants. We thank M. Krug (NU) for his assistance with casting, TEM and many useful discussions, A. Hunter (NU) and M. Diaz (NU) for their assistance with SEM and Dr. D. Isheim for his assistance with LEAP tomography. We thank Dr. K. Knipling (Naval Research Laboratory) for his suggestions regarding casting and heat treatment, Prof. C. Wolverton (NU) and Dr. Z. Mao (NU) for sharing the results of their first-principles calculations, and Dr. J. Boileau (Ford), Dr. B. Ghaffari (Ford) and Mr. C. Huskamp (Boeing) for numerous useful discussions. ",

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N1 - Funding Information: This research was sponsored by the Ford-Boeing-Northwestern University Alliance (81132882). Atom-probe tomographic measurements were performed at the Northwestern University Center for Atom-probe Tomography (NUCAPT). The LEAP tomography system was purchased and upgraded with funding from NSF-MRI (DMR-0420532) and ONR-DURIP (N00014-0400798, N00014-0610539, and N00014-0910781) Grants. We thank M. Krug (NU) for his assistance with casting, TEM and many useful discussions, A. Hunter (NU) and M. Diaz (NU) for their assistance with SEM and Dr. D. Isheim for his assistance with LEAP tomography. We thank Dr. K. Knipling (Naval Research Laboratory) for his suggestions regarding casting and heat treatment, Prof. C. Wolverton (NU) and Dr. Z. Mao (NU) for sharing the results of their first-principles calculations, and Dr. J. Boileau (Ford), Dr. B. Ghaffari (Ford) and Mr. C. Huskamp (Boeing) for numerous useful discussions.

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N2 - The effect of substituting 0.01 or 0.02 at.% Er for Sc in an Al-0.06 Zr-0.06 Sc at.% alloy was studied to develop cost-effective high-temperature aluminum alloys for aerospace and automotive applications. Spheroidal, coherent, L1 2-ordered Al 3(Sc, Zr, Er) precipitates with a structure consisting of an Er-enriched core surrounded by a Sc-enriched inner shell and a Zr-enriched outer shell (core/double-shell structure) were formed after aging at 400 °C. This core/double-shell structure strengthens the alloy, and renders it coarsening resistant for at least 64 days at 400 °C. This structure is formed due to sequential precipitation of solute elements according to their diffusivities, D, where D Er > D Sc > D Zr at 400 °C. Zr and Er are effective replacements for Sc, accounting for 33 ± 1% of the total precipitate solute content in an Al-0.06 Zr-0.04 Sc-0.02 Er at.% alloy aged at 400 °C for 64 days. Er accelerates precipitation kinetics at 400 °C, resulting in: (i) strengthening due to the elimination of lobed-cuboidal precipitates in favor of spheroidal precipitates; and (ii) a decrease in the incubation time for nucleation because D Er > D Sc. Finally, a two-stage aging treatment (24 h at 300 °C + 8 h at 400 °C) provides peak microhardness due to optimization of the nanostructure.

AB - The effect of substituting 0.01 or 0.02 at.% Er for Sc in an Al-0.06 Zr-0.06 Sc at.% alloy was studied to develop cost-effective high-temperature aluminum alloys for aerospace and automotive applications. Spheroidal, coherent, L1 2-ordered Al 3(Sc, Zr, Er) precipitates with a structure consisting of an Er-enriched core surrounded by a Sc-enriched inner shell and a Zr-enriched outer shell (core/double-shell structure) were formed after aging at 400 °C. This core/double-shell structure strengthens the alloy, and renders it coarsening resistant for at least 64 days at 400 °C. This structure is formed due to sequential precipitation of solute elements according to their diffusivities, D, where D Er > D Sc > D Zr at 400 °C. Zr and Er are effective replacements for Sc, accounting for 33 ± 1% of the total precipitate solute content in an Al-0.06 Zr-0.04 Sc-0.02 Er at.% alloy aged at 400 °C for 64 days. Er accelerates precipitation kinetics at 400 °C, resulting in: (i) strengthening due to the elimination of lobed-cuboidal precipitates in favor of spheroidal precipitates; and (ii) a decrease in the incubation time for nucleation because D Er > D Sc. Finally, a two-stage aging treatment (24 h at 300 °C + 8 h at 400 °C) provides peak microhardness due to optimization of the nanostructure.

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KW - Erbium

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KW - Scandium

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Coarsening resistance at 400 °c of precipitation-strengthened Al-Zr-Sc-Er alloys

Abstract

Funding

Keywords

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