@article{d46d91b156dc4ea393b579202668961c,
title = "Effects of Cr on the properties of multicomponent cobalt-based superalloys with ultra high γ{\textquoteright} volume fraction",
abstract = "Chromium is known to confer oxidation resistance on Co-based superalloys. Herein we studied the influence of Cr concentration on the properties of a Co-based superalloy, Co–30Ni–11Al–2Ti-5.5W-2.5Ta-0.1B (at.%), with high γ{\textquoteright}-volume fractions (up to 98%). Additions of 4, 8, or 12 at.% Cr decreased the γ{\textquoteright}-solvus temperature and the γ{\textquoteright}-volume fraction, while also reducing the mean radius of γ{\textquoteright}-particles. Synchrotron X-ray diffraction and atom-probe tomography confirmed that Cr reduces the lattice parameter misfit by altering the partitioning behavior of W between the γ- and γ{\textquoteright}-phases. Concomitantly, an increase in Cr content significantly improved the oxidation resistance of the alloy. The results indicate that 4 at.% Cr is sufficient to decrease the oxidation rate by two orders of magnitude. A creep study at 850 ∘C revealed that Cr does not affect adversely the creep performance in high γ{\textquoteright}-volume fraction Co-based superalloys, but the tendency toward γ{\textquoteright} rafting changes with Cr concentration. Compared to Ni3Al intermetallic compounds, the alloys with high γ{\textquoteright}-volume fraction studied exhibited a significantly higher creep resistance. This may be attributed to the increase in antiphase boundary energy caused by the addition of Cr, Ti, or Ta, and significant solid-solution hardening in the Co-based intermetallic γ{\textquoteright}-phase.",
keywords = "Cobalt-based superalloys, Creep, Lattice parameter misfit, Oxidation, Partitioning",
author = "Chung, {Ding Wen} and Toinin, {Jacques P.} and Lass, {Eric A.} and Seidman, {David N.} and Dunand, {David C.}",
note = "Funding Information: The authors acknowledge useful discussions with Dr. Daniel Sauza. This work was performed with the support of a financial assistance award 70NANB14H012 from the U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Material Design (CHiMaD). The scanning electron microscopy work made use of the EPIC facility of Northwestern University{\textquoteright}s NUANCE Center. Atom-probe tomography and samples were prepared at the Northwestern University Center for Atom-Probe Tomography (NUCAPT). The local-electrode atom-probe tomograph at NUCAPT was acquired and upgraded with the aid of equipment grants from the MRI program of the National Science Foundation ( NSF DMR-0420532 ) and the DURIP program of the Office of Naval Research ( N00014-0400798 , N00014-0610539 , N00014-0910781 ). NUCAPT received support from the MRSEC program ( NSF DMR-1121262 ) of the Materials Research Center, the SHyNE Resource ( NSF NNCI-1542205 ), and the Initiative for Sustainability and Energy at Northwestern (ISEN) . Funding Information: The authors acknowledge useful discussions with Dr. Daniel Sauza. This work was performed with the support of a financial assistance award 70NANB14H012 from the U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Material Design (CHiMaD). The scanning electron microscopy work made use of the EPIC facility of Northwestern University's NUANCE Center. Atom-probe tomography and samples were prepared at the Northwestern University Center for Atom-Probe Tomography (NUCAPT). The local-electrode atom-probe tomograph at NUCAPT was acquired and upgraded with the aid of equipment grants from the MRI program of the National Science Foundation (NSF DMR-0420532) and the DURIP program of the Office of Naval Research (N00014-0400798, N00014-0610539, N00014-0910781). NUCAPT received support from the MRSEC program (NSF DMR-1121262) of the Materials Research Center, the SHyNE Resource (NSF NNCI-1542205), and the Initiative for Sustainability and Energy at Northwestern (ISEN). Publisher Copyright: {\textcopyright} 2020 Elsevier B.V.",
year = "2020",
month = aug,
day = "15",
doi = "10.1016/j.jallcom.2020.154790",
language = "English (US)",
volume = "832",
journal = "Journal of Alloys and Compounds",
issn = "0925-8388",
publisher = "Elsevier BV",
}