2025/12/08 by Huang, Aomin, Zhu, Siya, Belcher, Calvin +4
Engineering · Materials Science · #Atomic Physics (physics.atom-ph) #FOS: Physical sciences #High Entropy Alloys Studies #Intermetallics and Advanced Alloy Properties #Materials Science (cond-mat.mtrl-sci) #Titanium Alloys Microstructure and Properties
paper · doi:10.48550/arxiv.2512.08080
openalex publication_date 2025/12/08 · openalex created_date 2025/12/11 · openalex updated_date 2026/07/28
Refractory complex concentrated alloys, composed of multiple principal refractory elements, are promising candidates for high-temperature structural applications due to their exceptional thermal stability and high melting points. However, their mechanical performance is often compromised by interstitial impurities, particularly oxygen, nitrogen, and carbon, which segregate to grain boundaries and promote embrittlement. In this study, we investigate the solubility and thermodynamic behavior of oxygen interstitials in a model NbTiHfTa RCCA system. We synthesized NbTiHfTa alloys with varying oxygen contents via plasma arc melting and characterized their phase evolution and microstructure using XRD, SEM, and TEM. Complementary computational modeling was performed using machine-learning interatomic potentials integrated with Monte Carlo simulations to probe oxygen interactions at the atomic scale. Our results reveal a solubility limit for oxygen between 0.8 and 1.0 atomic percentage, beyond which HfO2 formation is energetically favorable. This combined experimental-computational framework provides a predictive approach for managing interstitial behavior in RCCAs, enabling improved alloy design strategies for enhanced mechanical performance.