Pore-induced defects during thermo-mechanical fatigue of a fourth-generation single crystal superalloy

• Published in: Materials research letters Vol. 11; no. 8; pp. 678 - 687
• Main Authors: Tan, Zihao, Wang, Xinguang, Pang, Jianchao, Zou, Mingke, Tao, Yan, Tao, Xipeng, Zou, Chenglu, Yang, Yanhong, Liu, Jide, Liu, Jinlai, Li, Jinguo, Zhou, Yizhou, Sun, Xiaofeng
• Format: Journal Article
• Language: English
• Published: New York Taylor & Francis Ltd 03.08.2023; Taylor & Francis Group
• Subjects: Alloys; Crack initiation; Crystal defects; Deformation; deformation twins; element segregation; Fourth-generation single crystal superalloy; Investigations; Materials fatigue; Metal fatigue; micro-pores; Microscopy; Nucleation; Single crystals; Stress concentration; Superalloys; Temperature; thermo-mechanical fatigue; Twinning
• ISSN: 2166-3831; 2166-3831
• DOI: 10.1080/21663831.2023.2223558

Comparable investigation of pore-induced defects during in-phase (IP) and out-of-phase (OP) thermo-mechanical fatigue (TMF) were conducted on fourth-generation single crystal superalloy. It was discovered that recrystallizations and deformation twins would take shape near micro-pores at IP and OP cycling, respectively. High-resolution observation uncovered that the increasing a/6〈112〉 twinning dislocations and more frequent activation of 〈112〉{111} viscous slipping during OP-TMF accounted for twinning nucleation. Atom-scale mapping additionally disclosed the dual effect of Re, Co, and Cr in facilitating twinning formation and impeding of partial dislocations movement. It was deemed that the accumulation of pore-induced twins caused the premature fracture of alloy during OP-TMF.