Effect of Orientation on Stress-Rupture Property and Related Deformation Microstructure of a Ni-Base Re-containing Single-Crystal Superalloy at 900 °C

• Published in: Acta metallurgica sinica : English letters 2021-05, Vol.34 (5), p.719-728
• Main Authors: Wang, Guang-Lei, Liu, Jin-Lai, Liu, Ji-De, Zhou, Yi-Zhou, Sun, Xu-Dong, Zhang, Hai-Feng, Sun, Xiao-Feng
• Format: Article
• Language: English
• Subjects: Alloys; Anisotropy; Antiphase boundaries; Channels; Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Critical temperature; Cross slip; Deformation; Deformation effects; Experiments; High temperature; Load; Materials Science; Metal fatigue; Metallic Materials; Microcracks; Microstructure; Microtwins; Nanotechnology; Nickel base alloys; Organometallic Chemistry; Orientation effects; Scanning electron microscopy; Screw dislocations; Shearing; Single crystals; Spectroscopy/Spectrometry; Superalloys; Tribology
• ISSN: 1006-7191; 2194-1289
• DOI: 10.1007/s40195-020-01131-y

Stress-rupture properties of a Ni-base Re-containing single-crystal superalloy with three orientations have been tested under 900 °C/445 MPa. An obvious anisotropy of stress-rupture property is attributed to orientation reliant deformation microstructure. The good strength in [001] orientation is attributed to the rapid multiplication of dislocations active in horizontal channels and later γ’ cutting via dislocations pair coupled with anti-phase boundary. The microtwin formation largely limits the strength and plasticity as a result of the continuous shearing across γ / γ’ microstructure by {111}〈112〉 slip activated in [011] orientation. The property in [111] orientation results mainly from the lateral cross-slip movements of the screw dislocations within connected matrix channels as well as the precipitate shearing by coplanar dislocations. Microcracks all initially originate from the interdendritic micropores in three orientations. The critical temperature of stress-rupture anisotropy could be increased by a high level of refractory solutes especially Re.