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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Phase separation in equiatomic AlCoCrFeNi high-entropy alloy
1Helmholtz-Zentrum Berlin, Institute of Applied Materials, D-14109 Berlin, Germany.
Ultramicroscopy
|January 29, 2013
Summary
Microstructure analysis of AlCoCrFeNi high entropy alloys revealed distinct dendrites and interdendrites. These regions show phase separation, suggesting spinodal decomposition within the Cr-Fe-rich precipitates.
Area of Science:
- Materials Science
- Metallurgy
- Physical Chemistry
Background:
- High entropy alloys (HEAs) offer unique properties due to their complex compositions.
- Understanding the microstructure of as-cast HEAs is crucial for predicting their performance.
- AlCoCrFeNi is a prominent equimolar HEA with potential applications.
Purpose of the Study:
- To investigate the detailed microstructure of as-cast AlCoCrFeNi high entropy alloy.
- To identify phase distribution and elemental segregation within the alloy.
- To elucidate the underlying mechanism of phase separation.
Main Methods:
- Transmission Electron Microscopy (TEM) for microstructural imaging.
- Atom Probe Tomography (APT) for three-dimensional elemental mapping.
- Analysis of elemental distribution in dendrites and interdendrites.
Main Results:
- A pronounced dendritic and interdendritic microstructure was observed.
- Phase separation into an Al-Ni rich matrix and Cr-Fe rich precipitates occurred in both regions.
- Three-dimensional atom probe measurements revealed elemental fluctuations within the Cr-Fe rich phase.
Conclusions:
- The observed phase separation is consistent with spinodal decomposition.
- Elemental segregation plays a significant role in the microstructure of this HEA.
- The findings provide insights into the solidification and phase evolution of AlCoCrFeNi alloys.
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