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Elastic strain-induced amorphization in high-entropy alloys
Yeqiang Bu1,2, Yuan Wu3,4, Zhifeng Lei5
1Center for X-mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou, 310027, China.
Nature Communications
|May 30, 2024
Summary
High-entropy alloys (HEAs) exhibit a novel elastic instability, undergoing amorphization at high elastic strain. This phenomenon, driven by local atomic inhomogeneity, contrasts with traditional plasticity mechanisms in crystalline solids.
Area of Science:
- Materials Science
- Solid Mechanics
- Crystallography
Background:
- Elastic stability governs material responses like melting, plasticity, and fracture in crystalline solids.
- Previous studies focused on dislocation-mediated or defect accumulation-mediated amorphization.
- High-entropy alloys (HEAs) present unique material properties due to their complex atomic structures.
Purpose of the Study:
- To investigate elastic stability in high-entropy alloys (HEAs).
- To characterize the mechanism of amorphization under tensile loading in HEAs.
- To elucidate the relationship between local atomic environment and elastic strain-induced amorphization.
Main Methods:
- In situ mechanical testing under tensile loading.
- Atomic-resolution characterization using transmission electron microscopy (TEM).
- First-principles calculations and atomic-resolution chemical mapping.
Main Results:
- Observed sudden loss of lattice ordering (amorphization) in HEAs at approximately 10% elastic strain.
- Identified a novel elastic strain-induced amorphization mechanism distinct from dislocation or defect-mediated processes.
- Correlated amorphization with depressed dislocation nucleation, attributed to local atomic environment inhomogeneity in HEAs.
Conclusions:
- Elastic strain-induced amorphization represents a new form of elastic instability in HEAs.
- The findings highlight the critical role of local atomic environment inhomogeneity in HEA mechanical behavior.
- Provides fundamental insights into elastic instability and incipient plasticity in advanced materials.
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