Development of low-density γ/γ′ Co–Al–Ta-based superalloys with high solvus temperature

Yuechao Chen, Cuiping Wang, Jingjing Ruan, Shuiyuan Yang, Toshihiro Omori, Ryosuke Kainuma, Kiyohito Ishida, Jiajia Han, Yong Lu, Xingjun Liu

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53 Citations (Scopus)


The present paper reports the development of W-, Mo-, and V-free and Ni- and Cr-containing Co–Al–Ta-based superalloys. In particular, the presence of a metastable L12-γ′ phase is experimentally verified in Co–12Al–2Ta alloy. The results show that the γ′ phase stability is improved and the γ/γ′ composition range is broadened by rising the Ni content in alloys under study. Moreover, elemental partitioning proves that Cr was a γ-phase former, which addition reduces the γ/γ′ lattice misfit and the γ′ precipitate coarsening rate. Moreover, the developed Cr-containing alloys exhibit excellent γ′ phase stability even at high temperatures of 800–1100 °C. In particular, Co–30Ni–12Al–4Ta–12Cr (12Cr) alloy possesses a good combination of high solvus temperature (∼1152 °C), low density (∼8.38 g/cm3), low γ/γ′ lattice misfit (∼+0.33%), and low coarsening rate of γ′ precipitate (∼1.95 × 10−27 m/s at 900 °C). Besides, nominal and specific yield strength values of the developed 12Cr alloy at ambient and high temperatures are no worse than those of other available Cr-containing and W-free cobalt-based superalloys.

Original languageEnglish
Pages (from-to)652-664
Number of pages13
JournalActa Materialia
Publication statusPublished - 2020 Apr 15


  • Alloy development
  • Alloying effects
  • Co-based superalloys
  • Phase equilibria
  • γ/γ' Microstructure


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