| About this Abstract |
| Meeting |
MS&T21: Materials Science & Technology
|
| Symposium
|
Coatings to Protect Materials from Extreme Environments
|
| Presentation Title |
Polymorph Stability and Thermal Expansion Tensors of Mixed and High Entropy Rare Earth Disilicates |
| Author(s) |
Alejandro Salanova, Rachel Guarriello, Mackenzie Ridley, Cormac Toher, Stefano Curtarolo, Elizabeth Opila, Jon Ihlefeld |
| On-Site Speaker (Planned) |
Alejandro Salanova |
| Abstract Scope |
Entropic stabilization at high temperatures is a relatively new approach for developing robust thermal/environmental barrier coatings (T/EBCs). A challenge facing the realization of high entropy EBCs is achieving the necessary atomic scale mixing to achieve the multiple configurations required for large entropic contributions to free energy. In this work, multiple rare earth (RE) and high entropy alloy (HEA) disilicate powders are synthesized via sol-gel methods. The addition of multiple REs results in the stabilization of phases not readily formed for individual compounds. Combining REs leads to an “averaging” effect where phases not possible for single RE disilicates can be stabilized. The coefficient of thermal expansion second-rank tensor was determined for RE disilicates from temperature dependent X-ray diffraction. Knowledge of this tensor is vital for designing T/EBCs that are thermo-mechanically matched to the underlying material and can be used to design microstructures that minimize thermal stresses. |