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Liquid Phase Separation in High-Entropy Alloys-A Review
Nicholas Derimow1, Reza Abbaschian1
1Department of Materials Science and Engineering, University of California, Riverside, CA 92521, USA.
Entropy (Basel, Switzerland)
|December 3, 2020
Summary
High-entropy alloys (HEAs), also known as multi-principal element alloys (MPEAs), can undergo liquid phase separation due to positive mixing enthalpy. Certain elements like Co, Ni, and Ti promote miscibility, while others like Cr, V, and Nb increase separation.
Area of Science:
- Materials Science
- Metallurgy
- Physical Chemistry
Background:
- High-entropy alloys (HEAs), also termed multi-principal element alloys (MPEAs) or complex concentrated alloys (CCAs), have spurred innovation in unconventional alloy design.
- Research focuses on structure-property and processing relationships to enhance material properties beyond conventional alloys.
Purpose of the Study:
- To review and summarize experimental findings on liquid phase separation (LPS) in HEAs, MPEAs, and CCAs.
- To draw parallels between LPS in HEAs and conventional alloy systems.
- To elucidate the role of mixing enthalpy and entropy in LPS.
Main Methods:
- Literature review of experimental studies on liquid phase separation in multicomponent alloys.
- Analysis of thermodynamic factors, specifically mixing enthalpy and entropy.
- Identification of elemental effects on miscibility and liquid phase separation.
Main Results:
- Liquid phase separation in HEAs/MPEAs/CCAs is significantly influenced by positive mixing enthalpy and low entropy of mixing.
- Elements like Co, Ni, and Ti tend to promote miscibility, whereas Cr, V, and Nb increase the likelihood and temperature of liquid phase separation.
- Addition of Ni to specific compositions, such as CoCrCu, can eliminate immiscibility.
Conclusions:
- Liquid phase separation is a critical phenomenon in certain HEAs/MPEAs/CCAs, governed by thermodynamic parameters.
- Understanding elemental contributions to mixing enthalpy and entropy is key to controlling miscibility.
- Strategic alloy design, including Ni addition, can mitigate or prevent liquid phase separation, enabling tailored material properties.
Keywords:
CCAsHEAsMPEAscomplex concentrated alloyshigh-entropy alloysimmiscible alloysliquid phase separationmiscibility gapsmulti-principal element alloysmulticomponent alloysMore Related Videos
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