About this Abstract |
Meeting |
Superalloys 2024
|
Symposium
|
Superalloys 2024
|
Presentation Title |
Resistance to Viscoplastic Deformation of Ni-based SX Superalloys with Bimodal Distributions of Gamma-prime Precipitates |
Author(s) |
Luciana Maria Bortoluci Ormastroni, Jeremy Rame, Dominique Eyidi, Fabio Machado Alves da Fonseca, Jonathan Cormier |
On-Site Speaker (Planned) |
Luciana Maria Bortoluci Ormastroni |
Abstract Scope |
Ni-based single crystal (SX) superalloys have a well-established history of application in high pressure turbine (HPT) blades and vanes. Nowadays, these components are increasingly being employed in the first stage of the low pressure turbine (LPT). As a result, aircraft engine manufacturers are facing new challenges arising from the design, manufacturing processes, evolving service conditions, and refurbishment requirements. Conventionally, the capability of Ni-based SX superalloys to withstand the harshest environments is related to a homogeneous cuboidal γ/γ microstructure. However, future new applications have considered bimodal γ/γ' microstructures (presence of fine tertiary \947;' precipitates 10-100 nm inside theγγ-channels) resulting from either the manufacturing processes or from the routine use. This study investigates the resistance to the viscoplastic deformation of a 3rd generation Ni-based SX superalloy with a bimodal distribution of γ' precipitates. TEM observations showed presence of dislocations after heat treatment to achieve the bimodal microstructure. Even without plastic strain, dislocations were identified surrounding the secondary γ' precipitates. Stress relaxation and creep properties at 750 °C and 850 °C were very sensitive to such bimodal microstructure. Specimens with a bimodal γ' precipitation showed a creep life five to six times lower than the reference samples. According to the Norton’s type diagram, rate controlling deformation mechanisms of the reference and bimodal microstructures appear to be same at both temperatures and under different initial conditions (with and without prior plastic strain), but with a higher strain rate for the bimodal microstructure. |
Proceedings Inclusion? |
Definite: At-meeting proceedings |