About this Abstract |
| Meeting |
MS&T25: Materials Science & Technology
|
| Symposium
|
Phase Transformations in Ceramics: Science and Applications
|
| Presentation Title |
Synthesis of Refractory High Entropy Alloys (RHEAs) by Solid State Reduction of Oxides |
| Author(s) |
Wookyung Jin, Metri Zughbi, Ganesh Balasubramanian, Animesh Kundu, Helen M. Chan |
| On-Site Speaker (Planned) |
Helen M. Chan |
| Abstract Scope |
Enhanced reduction of oxide mixtures in dilute hydrogen-argon gas mixtures can be exploited to achieve metallic HEA (high entropy alloy) compositions. This technique has been successfully used to process the Cantor alloy derived quaternary CoFeMnNi, as well as refractory HEAs based on the MoNbTaW and CrNbMoV compositions. In addition to the entropy contribution (ΔS), it is proposed that the reduction of highly stable oxides (e.g. MnO and Nb<sub>2</sub>O<sub>5</sub>) is enhanced providing there is a negative enthalpy of solid solution (ΔH<sub>mix</sub>) of the metallic constituent in the alloy phase. A series of oxide mixtures targeting alloy compositions based on MoNbTaW and CrNbMoV were processed. Isothermal reduction experiments were carried out in 3% H<sub>2</sub> – Argon atmospheres for varying times. The resulting microstructures were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Phase identification was also performed using X-ray diffraction. The influence of composition on reduction will be discussed. |