Abstract
The thermo-mechanical response of micro-architectured tungsten coatings is characterized in the temperature range of 293 to 673 K using both in situ micro-compression experiments inside a scanning electron microscope (SEM) as well as image-based crystal plasticity finite element method (CPFEM) simulations. The experiments were conducted on micropillar-like specimens that were focus ion beam milled into the coatings, while the simulations were conducted on columnar-grained micropillar simulation cells constructed based on the statistics of the coating's microstructure. The experimental results show that the stress–strain response and deformation mode exhibit a strong temperature-dependence. At room temperature, catastrophic failure is observed shortly after yield and is manifested in the form of intergranular fracture and buckling of individual columnar grains. With increasing temperature, this catastrophic failure is gradually suppressed and the material exhibits a steadier strain hardening response at 693 K. The CPFEM simulations are also shown to be in good agreement with the experimental results, and these simulations indicate that the material response is strongly influenced by the local crystallographic anisotropy and microstructure inhomogeneity. Furthermore, the simulations capture the underlying mechanisms that control the temperature-dependent transition in deformation mode. The current results highlight that the micro-architectured microstructure offers a great combination of excellent mechanical strength and structural integrity at elevated temperatures, which is of importance for high temperature applications.
Original language | English |
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Article number | 104326 |
Journal | Journal of the Mechanics and Physics of Solids |
Volume | 150 |
DOIs | |
State | Published - May 2021 |
Funding
This research was sponsored by the Aerospace Materials for Extreme Environments program (Program Manager Dr. Ali Sayir) at the Air Force Office of Scientific Research (project number: FA9550-18-1-0071). Author Jiahao Cheng was sponsored by the Oak Ridge National Laboratory (ORNL) Manufacturing Science Division . ORNL is managed by UT-Battelle, LLC for the U.S. Department of Energy under Contract DE-AC05 00OR22725. The authors also thank Steven Lavenstein for assistance with preparation of the micro-cantilever beams. Discussions with David Cereceda at Villanova University on CPFEM modeling of tungsten are also greatly appreciated.
Funders | Funder number |
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Manufacturing Science Division | |
U.S. Department of Energy | DE-AC05 00OR22725 |
Air Force Office of Scientific Research | FA9550-18-1-0071 |
Oak Ridge National Laboratory |
Keywords
- Crystal plasticity
- Intergranular fracture
- Micro-architectured coatings
- Micro-compression
- Thermo-mechanical properties
- Tungsten