Abstract
The degradation of creep resistance in Ni-based single-crystal superalloys is essentially ascribed to their microstructural evolution. Yet there is a lack of work that manages to predict (even qualitatively) the effect of alloying element concentrations on the rate of microstructural degradation. In this research, a computational model is presented to connect the rafting kinetics of Ni superalloys to their chemical composition by combining thermodynamics calculation and a modified microstructural model. To simulate the evolution of key microstructural parameters during creep, the isotropic coarsening rate and γ/γ′ misfit stress are defined as composition-related parameters, and the effect of service temperature, time, and applied stress are taken into consideration. Two commercial superalloys, for which the kinetics of the rafting process are selected as the reference alloys, and the corresponding microstructural parameters are simulated and compared with experimental observations reported in the literature. The results confirm that our physical model not requiring any fitting parameters manages to predict (semiquantitatively) the microstructural parameters for different service conditions, as well as the effects of alloying element concentrations. The model can contribute to the computational design of new Ni-based superalloys.
Highlights
THE outstanding high-temperature mechanical performance of Ni-based single-crystal superalloys, in particular, their superior creep resistance, makes them favorite materials for turbine blades in aero engines.[1]
There still exists some space to increase the alloying levels of Cr, Ta, and Mo to further improve the precipitation strengthening while maintaining the microstructural stability of the matrix
A novel computational model for the microstructural stability of Ni-based single-crystal superalloys as a function of temperature and applied tensile stress was built by combining thermodynamics calculations and an energy-based microstructural model
Summary
THE outstanding high-temperature mechanical performance of Ni-based single-crystal superalloys, in particular, their superior creep resistance, makes them favorite materials for turbine blades in aero engines.[1]. In the early creep stage of so-called negative misfitting alloys, initially adjacent cuboidal c¢ particles coalesce and turn into platelike structures, which are normal to the stress direction. This microstructure of alternating platelets of c and c¢ phases is called the rafted structure. The widening of the c channel width, which is perpendicular to the uniaxial applied stress, is an important process in presenting creep kinetics during microstructural evolution, since the channel width determines the dislocation motion due to the Orowan mechanism and their accumulation. Other loading conditions (uniaxial compression, multiaxial stress, cyclic loading, etc.) are outside the scope of this work
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.
