Microstructure and mechanical properties of cast, eutectic Al-Ce-Ni-Mn-Sc-Zr alloys with multiple strengthening mechanisms

Clement N. Ekaputra; Jon Erik Mogonye; David C. Dunand

doi:10.1016/j.actamat.2024.120006

Microstructure and mechanical properties of cast, eutectic Al-Ce-Ni-Mn-Sc-Zr alloys with multiple strengthening mechanisms

Clement N. Ekaputra^*, Jon Erik Mogonye, David C. Dunand

^*Corresponding author for this work

Materials Science and Engineering

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

2 Scopus citations

Abstract

The effects of Ni additions on microstructure and microhardness of near-eutectic Al-9Ce-xNi-0.75Mn-0.18Sc-0.12Zr (x = 2.5, 3.2, and 3.9 wt.%) alloys are investigated for various cooling rates. The as-cast microstructure consists of fine, micron-scale Al₁₁Ce₃ and Ni-rich phases formed during eutectic solidification. Two Ni-rich phases are observed: (i) Al₂₇Ce₃Ni₆ at higher Ni contents and slower solidification rates, and (ii) Al₉(Ni,Mn,Fe)₂ at lower Ni contents and faster solidification rates. While these Ni-containing alloys have higher microhardness than a Ni-free control alloy, varying the Ni concentration in the 2.5–3.9 wt.% range does not significantly affect the microhardness, indicative of competing strengthening and weakening effects from adding Ni. The alloy with intermediate Ni content (3.2 wt.%) is selected for further microstructural and mechanical characterization. It contains four coarsening-resistant strengthening constituents: (i) micron-scale Al₁₁Ce₃ and (ii) Al₂₇Ce₃Ni₆ or Al₉(Ni,Mn,Fe)₂ platelets, all formed during eutectic solidification, (iii) L1₂-Al₃(Sc,Zr) nanoprecipitates formed on aging, and (iv) Mn atoms in solid solution in the α-Al matrix. The combined strengthening mechanisms impart high strength at ambient and elevated temperatures, as measured by microhardness (as a function of aging time), by compression and tensile experiments, and by compressive creep measurements. Alloys previously reported in the literature - with various combinations of one, two or three of these four strengthening phases - show lower hardness and creep resistance, indicating that cumulative strengthening can be achieved when combining mechanisms; the present alloy containing all four phases shows a remarkably high creep threshold stress of 62 MPa at 300 °C.

Original language	English (US)
Article number	120006
Journal	Acta Materialia
Volume	274
DOIs	https://doi.org/10.1016/j.actamat.2024.120006
State	Published - Aug 1 2024

Funding

This work made use of the MatCI Facility which receives support from the MRSEC Program ( NSF DMR-2308691 ) of the Materials Research Center at Northwestern University . This work made use of the CLaMMP Facility which receives support from the MRSEC Program ( NSF DMR-2308691 ) of the Materials Research Center at Northwestern University . This work made use of the EPIC facility of Northwestern University's NUANCE Center , which has received support from the SHyNE Resource ( NSF ECCS-2025633 ), the IIN, and Northwestern's MRSEC program ( NSF DMR-2308691 ). Atom-probe tomography was performed at the Northwestern University Center for Atom-Probe Tomography (NUCAPT) . The LEAP tomograph at NUCAPT was purchased and upgraded with grants from the NSF-MRI ( DMR-0420532 ) and ONR-DURIP ( N00014-0400798 , N00014-0610539 , N00014-0910781 , N00014-171287 0) programs. NUCAPT received support from the MRSEC program ( NSF DMR-1720139 ) at the Materials Research Center, the SHyNE Resource ( NSF ECCS-1542205 ), and the I nitiative for Sustainability and Energy (ISEN) at Northwestern University . This work made use of the Jerome B.Cohen X-Ray Diffraction Facility supported by the MRSEC program of the National Science Foundation ( DMR-2308691 ) at the Materials Research Center of Northwestern University and the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource ( NSF ECCS-2025633 .) The authors thank David Weiss (Eck Industries) for providing materials used to produce the alloys studied here, Tiffany Wu (Northwestern University, NU) for helpful discussions pertaining to fractographic analysis, and Dr. Brandon Ohl (NU) for experimental support. CNE was supported by the DEVCOM Army Research Laboratory (ARL) Research Associateship Program (RAP). Research was sponsored by the Army Research Laboratory and was accomplished under Cooperative Agreement Number W911NF-20-2-0292 and W911NF-21-2-0199. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory of the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. This work made use of the MatCI Facility which receives support from the MRSEC Program (NSF DMR-2308691) of the Materials Research Center at Northwestern University. This work made use of the CLaMMP Facility which receives support from the MRSEC Program (NSF DMR-2308691) of the Materials Research Center at Northwestern University. This work made use of the EPIC facility of Northwestern University's NUANCE Center, which has received support from the SHyNE Resource (NSF ECCS-2025633), the IIN, and Northwestern's MRSEC program (NSF DMR-2308691). Atom-probe tomography was performed at the Northwestern University Center for Atom-Probe Tomography (NUCAPT). The LEAP tomograph at NUCAPT was purchased and upgraded with grants from the NSF-MRI (DMR-0420532) and ONR-DURIP (N00014-0400798, N00014-0610539, N00014-0910781, N00014-1712870) programs. NUCAPT received support from the MRSEC program (NSF DMR-1720139) at the Materials Research Center, the SHyNE Resource (NSF ECCS-1542205), and the Initiative for Sustainability and Energy (ISEN) at Northwestern University. This work made use of the Jerome B.Cohen X-Ray Diffraction Facility supported by the MRSEC program of the National Science Foundation (DMR-2308691) at the Materials Research Center of Northwestern University and the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-2025633.) The authors thank David Weiss (Eck Industries) for providing materials used to produce the alloys studied here, Tiffany Wu (Northwestern University, NU) for helpful discussions pertaining to fractographic analysis, and Dr. Brandon Ohl (NU) for experimental support. CNE was supported by the DEVCOM Army Research Laboratory (ARL) Research Associateship Program (RAP). Research was sponsored by the Army Research Laboratory and was accomplished under Cooperative Agreement Number W911NF-20-2-0292 and W911NF-21-2-02199. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory of the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein.

Keywords

Aluminum alloys
Creep
Eutectic
High-temperature
Mechanical properties
Microstructure

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.2024.120006

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title = "Microstructure and mechanical properties of cast, eutectic Al-Ce-Ni-Mn-Sc-Zr alloys with multiple strengthening mechanisms",

abstract = "The effects of Ni additions on microstructure and microhardness of near-eutectic Al-9Ce-xNi-0.75Mn-0.18Sc-0.12Zr (x = 2.5, 3.2, and 3.9 wt.%) alloys are investigated for various cooling rates. The as-cast microstructure consists of fine, micron-scale Al11Ce3 and Ni-rich phases formed during eutectic solidification. Two Ni-rich phases are observed: (i) Al27Ce3Ni6 at higher Ni contents and slower solidification rates, and (ii) Al9(Ni,Mn,Fe)2 at lower Ni contents and faster solidification rates. While these Ni-containing alloys have higher microhardness than a Ni-free control alloy, varying the Ni concentration in the 2.5–3.9 wt.% range does not significantly affect the microhardness, indicative of competing strengthening and weakening effects from adding Ni. The alloy with intermediate Ni content (3.2 wt.%) is selected for further microstructural and mechanical characterization. It contains four coarsening-resistant strengthening constituents: (i) micron-scale Al11Ce3 and (ii) Al27Ce3Ni6 or Al9(Ni,Mn,Fe)2 platelets, all formed during eutectic solidification, (iii) L12-Al3(Sc,Zr) nanoprecipitates formed on aging, and (iv) Mn atoms in solid solution in the α-Al matrix. The combined strengthening mechanisms impart high strength at ambient and elevated temperatures, as measured by microhardness (as a function of aging time), by compression and tensile experiments, and by compressive creep measurements. Alloys previously reported in the literature - with various combinations of one, two or three of these four strengthening phases - show lower hardness and creep resistance, indicating that cumulative strengthening can be achieved when combining mechanisms; the present alloy containing all four phases shows a remarkably high creep threshold stress of 62 MPa at 300 °C.",

keywords = "Aluminum alloys, Creep, Eutectic, High-temperature, Mechanical properties, Microstructure",

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T1 - Microstructure and mechanical properties of cast, eutectic Al-Ce-Ni-Mn-Sc-Zr alloys with multiple strengthening mechanisms

AU - Ekaputra, Clement N.

AU - Mogonye, Jon Erik

AU - Dunand, David C.

PY - 2024/8/1

Y1 - 2024/8/1

N2 - The effects of Ni additions on microstructure and microhardness of near-eutectic Al-9Ce-xNi-0.75Mn-0.18Sc-0.12Zr (x = 2.5, 3.2, and 3.9 wt.%) alloys are investigated for various cooling rates. The as-cast microstructure consists of fine, micron-scale Al11Ce3 and Ni-rich phases formed during eutectic solidification. Two Ni-rich phases are observed: (i) Al27Ce3Ni6 at higher Ni contents and slower solidification rates, and (ii) Al9(Ni,Mn,Fe)2 at lower Ni contents and faster solidification rates. While these Ni-containing alloys have higher microhardness than a Ni-free control alloy, varying the Ni concentration in the 2.5–3.9 wt.% range does not significantly affect the microhardness, indicative of competing strengthening and weakening effects from adding Ni. The alloy with intermediate Ni content (3.2 wt.%) is selected for further microstructural and mechanical characterization. It contains four coarsening-resistant strengthening constituents: (i) micron-scale Al11Ce3 and (ii) Al27Ce3Ni6 or Al9(Ni,Mn,Fe)2 platelets, all formed during eutectic solidification, (iii) L12-Al3(Sc,Zr) nanoprecipitates formed on aging, and (iv) Mn atoms in solid solution in the α-Al matrix. The combined strengthening mechanisms impart high strength at ambient and elevated temperatures, as measured by microhardness (as a function of aging time), by compression and tensile experiments, and by compressive creep measurements. Alloys previously reported in the literature - with various combinations of one, two or three of these four strengthening phases - show lower hardness and creep resistance, indicating that cumulative strengthening can be achieved when combining mechanisms; the present alloy containing all four phases shows a remarkably high creep threshold stress of 62 MPa at 300 °C.

AB - The effects of Ni additions on microstructure and microhardness of near-eutectic Al-9Ce-xNi-0.75Mn-0.18Sc-0.12Zr (x = 2.5, 3.2, and 3.9 wt.%) alloys are investigated for various cooling rates. The as-cast microstructure consists of fine, micron-scale Al11Ce3 and Ni-rich phases formed during eutectic solidification. Two Ni-rich phases are observed: (i) Al27Ce3Ni6 at higher Ni contents and slower solidification rates, and (ii) Al9(Ni,Mn,Fe)2 at lower Ni contents and faster solidification rates. While these Ni-containing alloys have higher microhardness than a Ni-free control alloy, varying the Ni concentration in the 2.5–3.9 wt.% range does not significantly affect the microhardness, indicative of competing strengthening and weakening effects from adding Ni. The alloy with intermediate Ni content (3.2 wt.%) is selected for further microstructural and mechanical characterization. It contains four coarsening-resistant strengthening constituents: (i) micron-scale Al11Ce3 and (ii) Al27Ce3Ni6 or Al9(Ni,Mn,Fe)2 platelets, all formed during eutectic solidification, (iii) L12-Al3(Sc,Zr) nanoprecipitates formed on aging, and (iv) Mn atoms in solid solution in the α-Al matrix. The combined strengthening mechanisms impart high strength at ambient and elevated temperatures, as measured by microhardness (as a function of aging time), by compression and tensile experiments, and by compressive creep measurements. Alloys previously reported in the literature - with various combinations of one, two or three of these four strengthening phases - show lower hardness and creep resistance, indicating that cumulative strengthening can be achieved when combining mechanisms; the present alloy containing all four phases shows a remarkably high creep threshold stress of 62 MPa at 300 °C.

KW - Aluminum alloys

KW - Creep

KW - Eutectic

KW - High-temperature

KW - Mechanical properties

KW - Microstructure

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Microstructure and mechanical properties of cast, eutectic Al-Ce-Ni-Mn-Sc-Zr alloys with multiple strengthening mechanisms

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