|About this Abstract
||1st World Congress on High Entropy Alloys (HEA 2019)
||High Entropy Alloys 2019
||Study of Oxidation Mechanisms in Refractory MoWTaTiZr HEA using Periodic DFT and Atomistic Thermodynamic Modelling
||Eric Osei-Agyemang, Ganesh Balasubramanian
|On-Site Speaker (Planned)
High entropy alloys (HEA) based on refractory elements may achieve higher temperature operations with superior creep strength compared to Ni-based superalloys. At elevated temperatures, Mo based HEAs have been observed to exhibit good thermal and mechanical properties. Recently, a refractory Mo-W-Ta-Ti-Zr HEA was observed to exhibit greatly enhanced modulus of elasticity (3x at 300K) over near atomic cases and with higher moduli above 500K over commercial alloys (2.3x at 2000K).
The special quasi-random structures (SQS) model was used to generate random structures in combination with DFT to study oxidation mechanisms in Mo-W-Ta-Ti-Zr HEA. The best representative random structure is used to create different surfaces.
The stable facets are subsequently reacted with oxygen to gain a detailed understanding on surface oxidation processes. A link between theoretical and experimental conditions are established by using a thermodynamic approach to establish different temperature and pressure regimes on the oxidized surfaces at different oxygen coverages.