Atomistic Evolution of Hf2S/γ′ Interfaces in a Hf-containing Ni-based Single-Crystal Superalloy

• Published in: Acta metallurgica sinica : English letters Vol. 36; no. 6; pp. 1038 - 1046
• Main Authors: Lao, Zhezhu, Zhang, Xingpu, Wang, Jiangwei, Li, Jixue
• Format: Journal Article
• Language: English
• Published: Beijing The Chinese Society for Metals 01.06.2023; Springer Nature B.V
• Subjects: Alloys; Characterization and Evaluation of Materials; Chemistry and Materials Science; Columns (structural); Cooling; Corrosion and Coatings; Electron diffraction; Evolution; Grain boundaries; Interfaces; Materials Science; Metallic Materials; Nanotechnology; Nickel base alloys; Organometallic Chemistry; Oxidation; Precipitates; Sensors; Single crystals; Spectroscopy/Spectrometry; Stacking sequence (composite materials); Superalloys; Tribology; Interfacial segregation; S precipitate; Atomic structure; Ni-based single-crystal superalloy; Hf
• ISSN: 1006-7191; 2194-1289
• DOI: 10.1007/s40195-023-01541-8

The evolution of interfacial structures of needle-like sulfides in a Hf-containing Ni-based single-crystal superalloy has been studied with a combination of the state-of-the-art spherical aberration-corrected scanning transmission electron microscope and three-dimensional electron diffraction methods. The Hf 2 S precipitates possess an ABACBC stacking sequence with layered structure of Hf-S-Hf-Hf-S-Hf. The Hf 2 S/ γ ′ interfaces exhibit different types of metastable interfacial structures, including the sharp interface with segregated Hf atom columns, the one with indistinct transition region and the one with ordered transition region. These metastable structures represent the different stages of Hf 2 S growth during the aging process, based on which a sequential layer-by-layer growth mechanism of Hf 2 S is proposed.