Elevated temperature microstructural stability in cast AlCuMnZr alloys through solute segregation

A. Shyam; S. Roy; D. Shin; J. D. Poplawsky; L. F. Allard; Y. Yamamoto; J. R. Morris; B. Mazumder; J. C. Idrobo; A. Rodriguez; T. R. Watkins; J. A. Haynes

doi:10.1016/j.msea.2019.138279

Elevated temperature microstructural stability in cast AlCuMnZr alloys through solute segregation

A. Shyam, S. Roy, D. Shin, J. D. Poplawsky, L. F. Allard, Y. Yamamoto, J. R. Morris, B. Mazumder, J. C. Idrobo, A. Rodriguez, T. R. Watkins, J. A. Haynes

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

120 Scopus citations

Abstract

Commonly used commercial cast aluminum alloys for the automotive industry are viable for temperatures only up to 250 °C, despite decades of study and development. Affordable cast aluminum alloys with improved high-temperature mechanical properties are needed to enable the next generation of higher efficiency passenger car engines. Metastable θ′ (Al₂Cu) precipitates contribute to strengthening in Al–Cu alloys, but above 250 °C coarsen and transform, leading to poor mechanical properties. A major challenge has been to inhibit coarsening and transformation by stabilizing the metastable precipitates to higher temperatures. Here, we report compositions and associated counter-intuitive microstructures that allow cast Al–Cu alloys to retain their strength after lengthy exposures up to 350 °C, ∼70% of their absolute melting point. Atomic-scale characterization along with first-principles calculations demonstrate that microalloying with Mn and Zr (while simultaneously limiting Si to < 0.1 wt %) is key to stabilization of high-energy interfaces. It is suggested that segregation of Mn and Zr to the θ′ precipitate-matrix interfaces provides the mechanism by which the precipitates are stabilized to a higher homologous temperature.

Original language	English
Article number	138279
Journal	Materials Science and Engineering: A
Volume	765
DOIs	https://doi.org/10.1016/j.msea.2019.138279
State	Published - Sep 23 2019

Bibliographical note

Publisher Copyright:
© 2019 Elsevier B.V.

Funding

Research sponsored by the Propulsion Materials Program, DOE Vehicle Technologies Office. This research was performed under a Cooperative Research and Development Agreement (CRADA) between ORNL, Nemak and FCA US LLC. Research at the National Synchrotron Light Source X14A beamline was partially sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office and partially by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. We thank Dr. Jianming Bai for collecting the synchrotron data. The APT and EELS experiments were performed as a part of the User Program at Oak Ridge National Laboratory, Center for Nanophase Materials Sciences (CNMS), supported by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy (JCI, JDP and BM). JRM acknowledges support from the U.S.D.O.E. Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The authors thank Patrick Shower (ORNL), German Samolyuk (ORNL), Ben Larson (ORNL), Matthew Chisholm (ORNL) and Michael Brady (ORNL) for providing technical reviews of the paper and for providing many useful suggestions. Phil Staublin and Brian Milligan are acknowledged for image analysis. Dana McClurg (ORNL) and Shane Hawkins (ORNL) are thanked for their technical assistance. Research sponsored by the Propulsion Materials Program, DOE Vehicle Technologies Office . This research was performed under a Cooperative Research and Development Agreement (CRADA) between ORNL, Nemak and FCA US LLC. Research at the National Synchrotron Light Source X14A beamline was partially sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office and partially by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. We thank Dr. Jianming Bai for collecting the synchrotron data. The APT and EELS experiments were performed as a part of the User Program at Oak Ridge National Laboratory, Center for Nanophase Materials Sciences (CNMS), supported by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy (JCI, JDP and BM). JRM acknowledges support from the U.S.D.O.E. Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division . The authors thank Patrick Shower (ORNL), German Samolyuk (ORNL), Ben Larson (ORNL), Matthew Chisholm (ORNL) and Michael Brady (ORNL) for providing technical reviews of the paper and for providing many useful suggestions. Phil Staublin and Brian Milligan are acknowledged for image analysis. Dana McClurg (ORNL) and Shane Hawkins (ORNL) are thanked for their technical assistance.

Funders	Funder number
CNMS
FCA US LLC
German Samolyuk
JDP
Nemak
Oak Ridge National Laboratory
Office of Basic Energy Sciences
Patrick Shower
Scientific User Facilities Division
Shane Hawkins
U.S.D.O.E. Office of Science
U.S. Department of Energy
Office of Energy Efficiency and Renewable Energy
Basic Energy Sciences
Oak Ridge National Laboratory
Division of Materials Sciences and Engineering
Jingdezhen Ceramic Institute

Keywords

Density functional theory (DFT)
Mechanical properties
Microstructural stability
Solute segregation
cast aluminum alloys

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10.1016/j.msea.2019.138279

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Shyam, A., Roy, S., Shin, D., Poplawsky, J. D., Allard, L. F., Yamamoto, Y., Morris, J. R., Mazumder, B., Idrobo, J. C., Rodriguez, A., Watkins, T. R., & Haynes, J. A. (2019). Elevated temperature microstructural stability in cast AlCuMnZr alloys through solute segregation. Materials Science and Engineering: A, 765, Article 138279. https://doi.org/10.1016/j.msea.2019.138279

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abstract = "Commonly used commercial cast aluminum alloys for the automotive industry are viable for temperatures only up to 250 °C, despite decades of study and development. Affordable cast aluminum alloys with improved high-temperature mechanical properties are needed to enable the next generation of higher efficiency passenger car engines. Metastable θ′ (Al2Cu) precipitates contribute to strengthening in Al–Cu alloys, but above 250 °C coarsen and transform, leading to poor mechanical properties. A major challenge has been to inhibit coarsening and transformation by stabilizing the metastable precipitates to higher temperatures. Here, we report compositions and associated counter-intuitive microstructures that allow cast Al–Cu alloys to retain their strength after lengthy exposures up to 350 °C, ∼70% of their absolute melting point. Atomic-scale characterization along with first-principles calculations demonstrate that microalloying with Mn and Zr (while simultaneously limiting Si to < 0.1 wt %) is key to stabilization of high-energy interfaces. It is suggested that segregation of Mn and Zr to the θ′ precipitate-matrix interfaces provides the mechanism by which the precipitates are stabilized to a higher homologous temperature.",

keywords = "Density functional theory (DFT), Mechanical properties, Microstructural stability, Solute segregation, cast aluminum alloys",

author = "A. Shyam and S. Roy and D. Shin and Poplawsky, {J. D.} and Allard, {L. F.} and Y. Yamamoto and Morris, {J. R.} and B. Mazumder and Idrobo, {J. C.} and A. Rodriguez and Watkins, {T. R.} and Haynes, {J. A.}",

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AU - Allard, L. F.

AU - Yamamoto, Y.

AU - Morris, J. R.

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N2 - Commonly used commercial cast aluminum alloys for the automotive industry are viable for temperatures only up to 250 °C, despite decades of study and development. Affordable cast aluminum alloys with improved high-temperature mechanical properties are needed to enable the next generation of higher efficiency passenger car engines. Metastable θ′ (Al2Cu) precipitates contribute to strengthening in Al–Cu alloys, but above 250 °C coarsen and transform, leading to poor mechanical properties. A major challenge has been to inhibit coarsening and transformation by stabilizing the metastable precipitates to higher temperatures. Here, we report compositions and associated counter-intuitive microstructures that allow cast Al–Cu alloys to retain their strength after lengthy exposures up to 350 °C, ∼70% of their absolute melting point. Atomic-scale characterization along with first-principles calculations demonstrate that microalloying with Mn and Zr (while simultaneously limiting Si to < 0.1 wt %) is key to stabilization of high-energy interfaces. It is suggested that segregation of Mn and Zr to the θ′ precipitate-matrix interfaces provides the mechanism by which the precipitates are stabilized to a higher homologous temperature.

AB - Commonly used commercial cast aluminum alloys for the automotive industry are viable for temperatures only up to 250 °C, despite decades of study and development. Affordable cast aluminum alloys with improved high-temperature mechanical properties are needed to enable the next generation of higher efficiency passenger car engines. Metastable θ′ (Al2Cu) precipitates contribute to strengthening in Al–Cu alloys, but above 250 °C coarsen and transform, leading to poor mechanical properties. A major challenge has been to inhibit coarsening and transformation by stabilizing the metastable precipitates to higher temperatures. Here, we report compositions and associated counter-intuitive microstructures that allow cast Al–Cu alloys to retain their strength after lengthy exposures up to 350 °C, ∼70% of their absolute melting point. Atomic-scale characterization along with first-principles calculations demonstrate that microalloying with Mn and Zr (while simultaneously limiting Si to < 0.1 wt %) is key to stabilization of high-energy interfaces. It is suggested that segregation of Mn and Zr to the θ′ precipitate-matrix interfaces provides the mechanism by which the precipitates are stabilized to a higher homologous temperature.

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KW - Mechanical properties

KW - Microstructural stability

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Elevated temperature microstructural stability in cast AlCuMnZr alloys through solute segregation

Abstract

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