Microstructural Instabilities in Single Crystal Metals for Extreme Environments
Abstract
Predicting performance of structures under multi-field conditions at multiple time scales isneeded in conjunction with modeling and characterizing microstructure and material responses in a multiscale framework. A severe thermo-mechanical environments related to Air Force application is encountered in the hot section of aero-engines at the turbine blades made of Ni-based single crystal superalloys. They are subjected to multi-axial anisothermal high-temperature creep and dwell fatigue deformations either during in-service operations or severe certification procedures. This study proposes to investigate the thermo-mechanical responses of a Ni-based single crystal superalloy while exposed to thermal/stress conditions for which microstructural instabilities, such as lattice rotation and dissolution/precipitation, occur and modify the viscoplastic property. High-temperature and multi-axial stress conditions will be considered through synergetic multi-scale experimental and modeling approaches. Actually, the material will be characterized by advanced techniques, such as high-temperature pillar testing on both undeformed and deformed microstructures which will provide important information on the viscoplastic properties at the micro-scale. This information will serve as input for a phase field model aimed to predict microstructure evolutions. It will be coupled to a microstructure-sensitive thermomechanically-coupled damage model written in a crystal plasticity framework as well as to a dislocation dynamics model.The developed multi-scale framework will enhance understanding of the performance of single crystal metals under extreme environments. In addition, it will be a cornerstone in predicting material instabilities to improve safety and lower maintenance costs as well as in stepping toward an effective anisotropy design strategy of advanced materials.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 02, 2017
- Source ID
- FA95501710233
Entities
People
- Jean-briac Le Graverend
Organizations
- Air Force Office of Scientific Research
- Texas Engineering Experiment Station
- United States Air Force