Abstract
The dissolution kinetics of an ultra-fine γ’ precipitation occurring in the γ matrix between the standard secondary precipitates of MC2 Ni-based single crystal superalloy was investigated. Creep-fatigue experiments at 1050°C including an overheating at 1200°C were performed on <111> oriented specimens to study the effects of fine γ’ particles on the plastic deformation. During these experiments, a decrease of the plastic deformation rate was observed just after the temperature peak. This hardening effect disappears once the fine γ’ precipitates had been dissolved. A mean time for this hyperfine precipitation dissolution could then be highlighted. Based on both simple binary diffusion and complex diffusion analysis, the mean time for the dissolution of the fine γ’ precipitates is analyzed and compared to the experimental ones. It is shown that considering only a simple binary diffusion is not sufficient and it should be considered a more complex diffusive analysis involving additional interplays.
Highlights
Ni-based single crystal superalloys have been widely studied under a wide range of isothermal creep conditions [1,2]
Creep-fatigue experiments at 1050°C including an overheating at 1200°C were performed on oriented specimens to study the effects of fine γ’ particles on the plastic deformation
This paper is devoted to the study of the effect of an overheating on creep-fatigue behaviour at very high temperature in relation with the γ/γ’ evolutions, especially hyperfine γ’ ones
Summary
Ni-based single crystal superalloys have been widely studied under a wide range of isothermal creep conditions [1,2]. During in-service operation of twin engine helicopters, one of the two engines may unusually stops This implies a brutal rise up of the high pressure turbine blade temperature to around 1200°C for the remaining operating engine. It was established from these studies that the γ’ evolution is a significant creep controlling parameter It is well admitted in the literature, that the major loss of the mechanical properties at very high temperature (T>1100°C) is directly linked to the dissolution of the strengthening γ’ phase [1]. Simulation of the OEI ratings requires a special handling of the temperature control, temperature levels and heating/cooling rates In this context, this paper is devoted to the study of the effect of an overheating on creep-fatigue behaviour at very high temperature in relation with the γ/γ’ evolutions, especially hyperfine γ’ ones
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
