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Titanium Oxide Formation in TiCoCrFeMn High-Entropy Alloys.
Dominika Przygucka1, Adelajda Polkowska2, Wojciech Polkowski2
1Faculty of Advanced Technologies and Chemistry, Military University of Technology, Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
Materials (Basel, Switzerland)
|January 25, 2025
Summary
This study investigated oxide precipitates in high-entropy alloys. Unexpectedly, both methods yielded a mixture of anatase titanium dioxide and Ti2O3, not the expected rutile phase.
Area of Science:
- Materials Science
- Metallurgy
- Crystallography
Background:
- High-entropy alloys (HEAs) present structural identification challenges.
- Predicting phase structure is crucial for HEA functional properties.
- Strengthening HEAs with ceramic particles is a key research area.
Purpose of the Study:
- To investigate the structural outcome of introducing titanium dioxide (TiO2) precipitates into a TiCoCrFeMn high-entropy alloy.
- To compare ex situ and in situ methods for oxide precipitate introduction.
- To analyze phase reconstruction in the Ti-O system.
Main Methods:
- Ex situ introduction of anatase TiO2 and in situ reconstruction of CuO to TiO2.
- Homogenization at 1000 °C.
- Microscopic observations, X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), and Electron Backscatter Diffraction (EBSD).
Main Results:
- Contrary to expectations of rutile TiO2 formation, both introduction methods resulted in a mixture of anatase TiO2 and the Magnéli phase Ti2O3.
- Microscopic and crystallographic analyses confirmed the presence of these unexpected phases.
- Phase reconstruction analysis utilized changes in Gibbs free energy.
Conclusions:
- The formation of rutile TiO2 was not achieved under the studied conditions.
- The final strengthening phase in the TiCoCrFeMn alloy was a composite of anatase TiO2 and Ti2O3.
- Understanding phase stability and transformation is critical for designing novel high-entropy materials.
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