Low-density, W-free Co–Nb–V–Al-based superalloys with γ/γ’ microstructure

Fernando L. Reyes Tirado; Spencer V. Taylor; David C. Dunand

doi:10.1016/j.msea.2020.139977

Low-density, W-free Co–Nb–V–Al-based superalloys with γ/γ’ microstructure

Fernando L. Reyes Tirado, Spencer V. Taylor, David C. Dunand^*

^*Corresponding author for this work

Materials Science and Engineering

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

15 Scopus citations

Abstract

Previously-reported metastable γ′-L1₂ Co₃(Nb_0.65V_0.35) precipitates in the Co–6Nb–6V (at. %) ternary alloy are stabilized by additions of Al, Ti, Ni and Cr to the alloy. We identify two such multinary γ/γ′ alloys - with compositions of Co–10Ni–6Ti–5Al-xCr-3Nb–3V-0.04B at.% (with x = 0 and 4% Cr) - with γ′-precipitates remaining stable for up to 1000 h at 850 °C, with no additional phases present. Decreasing the Ti concentration from 6 to 2%, two more γ/γ′ superalloys - Co–10Ni–5Al-xCr-3Nb–3V–2Ti-0.04B (with x = 4 and 8% Cr) – are created with stable γ′-precipitates (measured for 168 h at 850 °C) with morphologies more cuboidal than for the first two alloys with 6%Ti. These submicron cuboidal γ′ precipitates are arranged into crystallographically-oriented sheets with small (<50 nm) γ′-spacing within sheets and larger (~100 nm) γ′-spacing between sheets. The alloy with the highest 8% Cr concentration shows, after aging at 850 °C for 24 h, γ′-nanoprecipitates with (Co_0.85Ni_0.15)₃(Ti_0.1₃Al_0.25 Nb_0.24Cr_0.21V_0.16B_0.₀₁) composition (assuming full segregation onto the two sublattices), with Al and Ti replacing at a similar rate both Nb and V in the ternary Co₃(Nb_0.65V_0.35). This high-Cr alloy exhibits the best oxidation resistance, as seen by a reduction in the parabolic growth rate constant and surface oxide thickness. Also, the present W- and Ta-free, Cr-containing superalloys show good creep resistance at 850 °C, which is comparable to other recent Cr-containing Co-base γ/γ′ superalloys with higher densities: (i) W-containing Co–9W–9Al–8Cr (at.%), and (ii) Ta-containing Co–10Ni–5Al–4Cr–3Ta–3V–2Ti-0.04B (at.%). This is the first report of a family of Co–Nb–V–Al-based γ/γ′-superalloys with low density (<8.0 g/cm³).

Original language	English (US)
Article number	139977
Journal	Materials Science and Engineering: A
Volume	796
DOIs	https://doi.org/10.1016/j.msea.2020.139977
State	Published - Oct 7 2020

Funding

This study was supported by the U.S. Department of Commerce, National Institute of Standards and Technology , as part of the Center for Hierarchical Materials Design (CHiMaD) at Northwestern University (NU) via award 70NANB14H012 . F.L.R.T acknowledges the support of a NSF Graduate Research Fellowship . S.T. acknowledges the support of the NU-MRSEC Research Experience for Undergraduates ( NSF DMR-1720139 ) and the 3M Corporation. 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 MatCI Facility which receives support from the MRSEC Program ( NSF DMR- 1720139 ) of the Materials Research Center at Northwestern University; the EPIC facility of Northwestern University's NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource ( NSF ECCS-1542205 ); the MRSEC program ( NSF DMR-1720139 ) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; the State of Illinois, through the IIN. The authors gratefully acknowledge experimental assistance from Mr. Brandon Ohl, Dr. Ding-Wen Chung, Dr. Richard Michi, Dr. Fei Xue and Dr. Amir Farkoosh (NU) and useful discussions with Dr. Ding-Wen Chung and Prof. D.N. Seidman (NU). S.T. thanks Prof. Marcus Young (University of North Texas) for use of DSC equipment. This study was supported by the U.S. Department of Commerce, National Institute of Standards and Technology, as part of the Center for Hierarchical Materials Design (CHiMaD) at Northwestern University (NU) via award 70NANB14H012. F.L.R.T acknowledges the support of a NSF Graduate Research Fellowship. S.T. acknowledges the support of the NU-MRSEC Research Experience for Undergraduates (NSF DMR-1720139) and the 3M Corporation. 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 MatCI Facility which receives support from the MRSEC Program (NSF DMR- 1720139) of the Materials Research Center at Northwestern University; the EPIC facility of Northwestern University's NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; the State of Illinois, through the IIN. The authors gratefully acknowledge experimental assistance from Mr. Brandon Ohl, Dr. Ding-Wen Chung, Dr. Richard Michi, Dr. Fei Xue and Dr. Amir Farkoosh (NU) and useful discussions with Dr. Ding-Wen Chung and Prof. D.N. Seidman (NU). S.T. thanks Prof. Marcus Young (University of North Texas) for use of DSC equipment.

Keywords

Atom probe tomography (APT)
Cobalt-base superalloys
Creep
Microstructure
Precipitates

ASJC Scopus subject areas

General Materials Science
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

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10.1016/j.msea.2020.139977

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title = "Low-density, W-free Co–Nb–V–Al-based superalloys with γ/γ{\textquoteright} microstructure",

abstract = "Previously-reported metastable γ′-L12 Co3(Nb0.65V0.35) precipitates in the Co–6Nb–6V (at. %) ternary alloy are stabilized by additions of Al, Ti, Ni and Cr to the alloy. We identify two such multinary γ/γ′ alloys - with compositions of Co–10Ni–6Ti–5Al-xCr-3Nb–3V-0.04B at.% (with x = 0 and 4% Cr) - with γ′-precipitates remaining stable for up to 1000 h at 850 °C, with no additional phases present. Decreasing the Ti concentration from 6 to 2%, two more γ/γ′ superalloys - Co–10Ni–5Al-xCr-3Nb–3V–2Ti-0.04B (with x = 4 and 8% Cr) – are created with stable γ′-precipitates (measured for 168 h at 850 °C) with morphologies more cuboidal than for the first two alloys with 6%Ti. These submicron cuboidal γ′ precipitates are arranged into crystallographically-oriented sheets with small (<50 nm) γ′-spacing within sheets and larger (~100 nm) γ′-spacing between sheets. The alloy with the highest 8% Cr concentration shows, after aging at 850 °C for 24 h, γ′-nanoprecipitates with (Co0.85Ni0.15)3(Ti0.13Al0.25 Nb0.24Cr0.21V0.16B0.01) composition (assuming full segregation onto the two sublattices), with Al and Ti replacing at a similar rate both Nb and V in the ternary Co3(Nb0.65V0.35). This high-Cr alloy exhibits the best oxidation resistance, as seen by a reduction in the parabolic growth rate constant and surface oxide thickness. Also, the present W- and Ta-free, Cr-containing superalloys show good creep resistance at 850 °C, which is comparable to other recent Cr-containing Co-base γ/γ′ superalloys with higher densities: (i) W-containing Co–9W–9Al–8Cr (at.%), and (ii) Ta-containing Co–10Ni–5Al–4Cr–3Ta–3V–2Ti-0.04B (at.%). This is the first report of a family of Co–Nb–V–Al-based γ/γ′-superalloys with low density (<8.0 g/cm3).",

keywords = "Atom probe tomography (APT), Cobalt-base superalloys, Creep, Microstructure, Precipitates",

author = "{Reyes Tirado}, {Fernando L.} and Taylor, {Spencer V.} and Dunand, {David C.}",

note = "Publisher Copyright: {\textcopyright} 2020 Elsevier B.V.",

year = "2020",

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day = "7",

doi = "10.1016/j.msea.2020.139977",

language = "English (US)",

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journal = "Materials Science and Engineering: A",

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TY - JOUR

T1 - Low-density, W-free Co–Nb–V–Al-based superalloys with γ/γ’ microstructure

AU - Reyes Tirado, Fernando L.

AU - Taylor, Spencer V.

AU - Dunand, David C.

PY - 2020/10/7

Y1 - 2020/10/7

N2 - Previously-reported metastable γ′-L12 Co3(Nb0.65V0.35) precipitates in the Co–6Nb–6V (at. %) ternary alloy are stabilized by additions of Al, Ti, Ni and Cr to the alloy. We identify two such multinary γ/γ′ alloys - with compositions of Co–10Ni–6Ti–5Al-xCr-3Nb–3V-0.04B at.% (with x = 0 and 4% Cr) - with γ′-precipitates remaining stable for up to 1000 h at 850 °C, with no additional phases present. Decreasing the Ti concentration from 6 to 2%, two more γ/γ′ superalloys - Co–10Ni–5Al-xCr-3Nb–3V–2Ti-0.04B (with x = 4 and 8% Cr) – are created with stable γ′-precipitates (measured for 168 h at 850 °C) with morphologies more cuboidal than for the first two alloys with 6%Ti. These submicron cuboidal γ′ precipitates are arranged into crystallographically-oriented sheets with small (<50 nm) γ′-spacing within sheets and larger (~100 nm) γ′-spacing between sheets. The alloy with the highest 8% Cr concentration shows, after aging at 850 °C for 24 h, γ′-nanoprecipitates with (Co0.85Ni0.15)3(Ti0.13Al0.25 Nb0.24Cr0.21V0.16B0.01) composition (assuming full segregation onto the two sublattices), with Al and Ti replacing at a similar rate both Nb and V in the ternary Co3(Nb0.65V0.35). This high-Cr alloy exhibits the best oxidation resistance, as seen by a reduction in the parabolic growth rate constant and surface oxide thickness. Also, the present W- and Ta-free, Cr-containing superalloys show good creep resistance at 850 °C, which is comparable to other recent Cr-containing Co-base γ/γ′ superalloys with higher densities: (i) W-containing Co–9W–9Al–8Cr (at.%), and (ii) Ta-containing Co–10Ni–5Al–4Cr–3Ta–3V–2Ti-0.04B (at.%). This is the first report of a family of Co–Nb–V–Al-based γ/γ′-superalloys with low density (<8.0 g/cm3).

AB - Previously-reported metastable γ′-L12 Co3(Nb0.65V0.35) precipitates in the Co–6Nb–6V (at. %) ternary alloy are stabilized by additions of Al, Ti, Ni and Cr to the alloy. We identify two such multinary γ/γ′ alloys - with compositions of Co–10Ni–6Ti–5Al-xCr-3Nb–3V-0.04B at.% (with x = 0 and 4% Cr) - with γ′-precipitates remaining stable for up to 1000 h at 850 °C, with no additional phases present. Decreasing the Ti concentration from 6 to 2%, two more γ/γ′ superalloys - Co–10Ni–5Al-xCr-3Nb–3V–2Ti-0.04B (with x = 4 and 8% Cr) – are created with stable γ′-precipitates (measured for 168 h at 850 °C) with morphologies more cuboidal than for the first two alloys with 6%Ti. These submicron cuboidal γ′ precipitates are arranged into crystallographically-oriented sheets with small (<50 nm) γ′-spacing within sheets and larger (~100 nm) γ′-spacing between sheets. The alloy with the highest 8% Cr concentration shows, after aging at 850 °C for 24 h, γ′-nanoprecipitates with (Co0.85Ni0.15)3(Ti0.13Al0.25 Nb0.24Cr0.21V0.16B0.01) composition (assuming full segregation onto the two sublattices), with Al and Ti replacing at a similar rate both Nb and V in the ternary Co3(Nb0.65V0.35). This high-Cr alloy exhibits the best oxidation resistance, as seen by a reduction in the parabolic growth rate constant and surface oxide thickness. Also, the present W- and Ta-free, Cr-containing superalloys show good creep resistance at 850 °C, which is comparable to other recent Cr-containing Co-base γ/γ′ superalloys with higher densities: (i) W-containing Co–9W–9Al–8Cr (at.%), and (ii) Ta-containing Co–10Ni–5Al–4Cr–3Ta–3V–2Ti-0.04B (at.%). This is the first report of a family of Co–Nb–V–Al-based γ/γ′-superalloys with low density (<8.0 g/cm3).

KW - Atom probe tomography (APT)

KW - Cobalt-base superalloys

KW - Creep

KW - Microstructure

KW - Precipitates

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JO - Materials Science and Engineering: A

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M1 - 139977

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Low-density, W-free Co–Nb–V–Al-based superalloys with γ/γ’ microstructure

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