|About this Abstract
||2022 TMS Annual Meeting & Exhibition
||Phase Transformations and Microstructural Evolution
||Advanced Characterization of High-temperature Oxygen-induced Phase Evolution in NbTiZr
||David Beaudry, Daniel Foley, Elaf Anber, Jean-Philippe Couzinié, Loïc Perrière, Keith Knipling, Christopher Pasco, Tyrel McQueen, Michael Waters, James Rondinelli, Mitra Taheri
|On-Site Speaker (Planned)
Refractory High Entropy Alloys (RHEAs) offer a potential alternative to Ni-based superalloys in high-temperature applications because of their specific strength at elevated temperatures. These alloys often exhibit detrimental oxidation behavior due to their constituent refractory elements. Some RHEA compositions exhibit phase transformations that can both influence and be influenced by oxygen content. NbTiZr, a common derivative of studied RHEAs, was selected to better understand the fundamental oxide formation and evolution in these systems. Annealing heat treatments were performed at 900°C, 1050°C, and 1250°C followed by oxidation treatments at the same temperatures. A multi-layered surface microstructure formed. High Resolution TEM and APT revealed that the high-temperature oxygen influx stabilized a low-temperature phase transformation, resulting in a suboxide layer of two metallic phases with distinct oxygen content. The interplay of these oxygen-stabilized phases with oxide precipitation offers a novel “bottom-up” approach to tune phase transformations at the bulk-oxide interface.
||High-Entropy Alloys, High-Temperature Materials, Phase Transformations