|About this Abstract
||1st World Congress on High Entropy Alloys (HEA 2019)
||High Entropy Alloys 2019
||P31: Correlated In-situ Study of Surface Oxidation of High Entropy Alloys
||Bharat Gwalani, Libor Kovarik, Sten Lambeets, Daniel Perea, Arun Devaraj
|On-Site Speaker (Planned)
Alloys undergo surface reactions when exposed to reactive gaseous environments especially at high-temperatures. Such gas-metal reactions directly modify the surface composition-structure, affecting the performance. However, atomistic-mechanisms responsible for such changes are still inadequately understood especially in compositionally complex alloys like high entropy alloys (HEAs). Hence, a multimodal in-situ chemical imaging of such changes in a transition-metal (Al, Cr, Co, Fe, Ni) based HEA during exposure to a controlled oxygen environment at 300-500 oC was performed. We demonstrate the changes to the composition and crystal structure of the surface and sub-surface regions of the HEA using an in-situ gas reaction-cell in the transmission electron microscope (TEM) and environmental reaction chamber associated with an atom probe tomography (APT) instrument. A direct correlation of time-dependent variation of structure, composition and chemical state will aid in developing accurate predictive mechanistic models.