Effect of annealing treatment on microstructure evolution and creep behavior of a multiphase Ni3Al-based superalloy

Jing Wu, Chong Li, Yongchang Liu, Yuting Wu, Qianying Guo, Huijun Li, Haipeng Wang

Research output: Contribution to journalArticlepeer-review

83 Scopus citations

Abstract

The microstructure evolution and creep behavior of a novelly designed as-cast Ni3Al-based superalloy with multiphase configuration are investigated by high-temperature annealing treatments. The as-cast microstructure comprises dominant γ′+γ dendritic and less (~19.37 vol%) interdendritic β areas, annealing treatments at 1160–1280 °C promoted the growth of γ’ phase in the γ’+γ dendrite, during which the interdendritic β phase aggregated and coarsened rapidly in width with keeping its relatively constant volume fraction. Meanwhile, the annealing treatments significantly promoted the precipitation of quasi-spherical α-Cr phase particles within the β phase. The original as-cast microstructure exhibited inferior creep resistance at 800 °C/200 MPa with the shortest creep rupture life of 194 h, however, the annealing treatments at 1160–1280 °C prolonged the creep rupture life to beyond 611 h. Although the steady-state creep rate was gradually reduced with increasing annealing temperatures, the creep ductility was degraded by higher-temperature annealing at 1240 and 1280 °C compared with original as-cast microstructure. The 1160 °C annealed microstructure exhibited the longest creep rupture life of 665 h and the maximum creep strain to fracture of 3.21%, while the minimum steady-state creep rate was obtained on account of the largest γ’ phase sized 0.91 µm after annealing at 1280 °C. Despite its positive role in the castability, thermoplasticity and weldability of the explored multiphase Ni3Al-based superalloy, interdendritic β phase has negative effects on the creep properties due to its incoherent existence with the dominant γ′+γ dendrite.

Original languageEnglish
Pages (from-to)623-635
Number of pages13
JournalMaterials Science and Engineering: A
Volume743
DOIs
StatePublished - 16 Jan 2019

Keywords

  • Annealing treatment
  • Creep behavior
  • Intermetallics
  • Microstructure evolution
  • NiAl-based superalloy

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