TY - JOUR
T1 - On the possibility of simultaneously achieving sufficient oxidation resistance and creep property at high temperatures exceeding 1000 °C in Co-based superalloys
AU - Chen, Zhenghao
AU - Okamoto, Norihiko L.
AU - Chikugo, Kazuyoshi
AU - Inui, Haruyuki
N1 - Funding Information:
This work was supported by Grant-in-Aids for Scientific Research on innovative Areas on High Entropy Alloys through the grant number JP18H-05450 and JP18H-05451 , and in part by JSPS KAKENHI grant numbers 18H01735 , 18H05478 , 19H00824 and by the Elements Strategy Initiative for Structural Materials (ESISM) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan .
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2021/3/25
Y1 - 2021/3/25
N2 - Effects of additions of γ’ (L12)-forming elements (Ta, Ti and Ni; for creep property) and γ (FCC)-forming elements (Cr and Si; for oxidation resistance) on the microstructural stability, oxidation resistance and creep properties of two-phase γ/γ′ Co-based superalloys based on the Co–Al–W systems have been investigated in order to see whether simultaneous achievement of sufficient oxidation resistance and creep property for the usage above 1000 °C is possible or not for Co-based superalloys. A candidate composition ((Co0.8Ni0.2)-6Al–2W–2Ta–6Ti–8Cr–1Si) that provides relatively high γ′ solvus temperature and high γ′ volume fraction is found. The alloy with the candidate composition exhibits superior oxidation resistance when compared to Cr-free alloys but the creep property is not as good as expected from the high γ′ solvus temperature and high γ’ volume fraction and is only comparable to those of Ni-based superalloys of the first generation. The reason for the modest creep properties of the candidate alloy as well as possibilities for further investigation to simultaneously achieve sufficient oxidation resistance and creep property for Co-based superalloys are discussed.
AB - Effects of additions of γ’ (L12)-forming elements (Ta, Ti and Ni; for creep property) and γ (FCC)-forming elements (Cr and Si; for oxidation resistance) on the microstructural stability, oxidation resistance and creep properties of two-phase γ/γ′ Co-based superalloys based on the Co–Al–W systems have been investigated in order to see whether simultaneous achievement of sufficient oxidation resistance and creep property for the usage above 1000 °C is possible or not for Co-based superalloys. A candidate composition ((Co0.8Ni0.2)-6Al–2W–2Ta–6Ti–8Cr–1Si) that provides relatively high γ′ solvus temperature and high γ′ volume fraction is found. The alloy with the candidate composition exhibits superior oxidation resistance when compared to Cr-free alloys but the creep property is not as good as expected from the high γ′ solvus temperature and high γ’ volume fraction and is only comparable to those of Ni-based superalloys of the first generation. The reason for the modest creep properties of the candidate alloy as well as possibilities for further investigation to simultaneously achieve sufficient oxidation resistance and creep property for Co-based superalloys are discussed.
KW - Co-based superalloy
KW - Creep
KW - Oxidation resistance
KW - Phase equilibria
KW - Scanning electron microscopy (SEM)
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U2 - 10.1016/j.jallcom.2020.157724
DO - 10.1016/j.jallcom.2020.157724
M3 - Article
AN - SCOPUS:85094973083
VL - 858
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
SN - 0925-8388
M1 - 157724
ER -