Temperature-Dependent Mechanical Behaviors and Deformation Mechanisms in a Si-Added Medium-Entropy Superalloy with L1<sub>2</sub> Precipitation
Tuanwei Zhang,
Tianxiang Bai,
Renlong Xiong,
Shunhui Luo,
Hui Chang,
Shiyu Du,
Jinyao Ma,
Zhiming Jiao,
Shengguo Ma,
Jianjun Wang,
Zhihua Wang
Affiliations
Tuanwei Zhang
Institute of Applied Mechanics, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Tianxiang Bai
Institute of Applied Mechanics, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Renlong Xiong
Hubei Provincial Key Laboratory of Chemical Equipment Intensification and Intrinsic Safety, School of Mechanical and Electrical Engineering, Wuhan Institute of Technology, Wuhan 430205, China
Shunhui Luo
Institute of Applied Mechanics, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Hui Chang
Institute of Applied Mechanics, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Shiyu Du
Institute of Applied Mechanics, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Jinyao Ma
Institute of Applied Mechanics, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Zhiming Jiao
Institute of Applied Mechanics, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Shengguo Ma
Institute of Applied Mechanics, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Jianjun Wang
Institute of Applied Mechanics, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Zhihua Wang
Institute of Applied Mechanics, College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, China
A novel Ni-Co-Cr-based medium-entropy superalloy with a high Si content (7.5 at%) strengthened by an L12 phase was developed. The pure L12 phase, characterized by an average size of 50 nm and a volume fraction of 46%, was precipitated within the FCC matrix. This alloy exhibits excellent mechanical properties over a wide range of temperatures from 77 K to 1073 K. A yield strength of 1005 MPa, an ultimate tensile strength of 1620 MPa, and a tensile elongation of 36% were achieved at 77 K, with a maximum value of 4.8 GPa at the second stage of the work-hardening rate. The alloy maintains a basically consistent yield strength of approximately 800 MPa from 298 K to 973 K, showcasing significant strain-hardening capabilities, with values of 2.5 GPa, 3.7 GPa, and 4.8 GPa at 873 K, 298 K, and 77 K, respectively. Microscopic analysis revealed that at room and cryogenic temperatures, multilayer stacking faults (SFs), SF bands, and SF networks, rather than twins, effectively stored a large number of dislocations and impeded dislocation movement, thereby enhancing the work-hardening ability of the alloy. Furthermore, at 773 K, the primary deformation mechanism involved high-density dislocation walls (HDDWs) consisting of dislocation tangles and SF lines. As the temperature rose to 973 K, the work-hardening process was influenced by the APB shearing mechanism (in the form of dislocation pairs), SF lines, and microtwins generated through atomic rearrangement. This study not only provides valuable insights for the development of new oxidation-resistant superalloys but also enhances our understanding of high-temperature deformation mechanisms.
