Acceleration Mechanism of Intergranular Cracking of Ni-Base Superalloy GH4169 under Creep Loading at Elevated Temperatures due to the Growth of δ-Phase

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  • NAKAYAMA Ayumi
    Department of Finemechanics, Graduate School of Engineering, Tohoku University
  • WANG Run-Zi
    Fracture and Reliability Research Institute, Graduate School of Engineering, Tohoku University
  • SUZUKI Ken
    Fracture and Reliability Research Institute, Graduate School of Engineering, Tohoku University
  • MIURA Hideo
    Fracture and Reliability Research Institute, Graduate School of Engineering, Tohoku University

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Other Title
  • 高温クリープ負荷環境におけるNi基超合金GH4169のδ相析出による粒界割れ加速機構の解明

Abstract

<p>In order to quantitatively clarify the effect of δ-phase precipitation on the strength of grain boundary in Ni-based superalloy GH4169 at elevated temperatures, which is expected to be used in aircraft engines, intermittent creep tests at 800°C were conducted on specimens, and the microstructural changes were analyzed using EBSD analysis. The effects of δ-phase precipitation and creep damage were evaluated by micro tensile tests. It was confirmed that there is a large lattice mismatch between the δ-phase precipitated around the grain boundary and the matrix phase, and that dislocations and voids accumulate in the grain boundary. It was also suggested that the δ phase precipitation may be a stress-induced diffusion phenomenon. Furthermore, it was confirmed that the strength of this alloy decreased in the early period of creep, influenced by both creep damage and the precipitation of δ-phase.</p>

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