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Updated: Aug 6, 2026
08:55
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Deciphering the compositional complexity and sublattice site occupancy toward strong-yet-ductile L12-type
Jie Gan1, Lin Yuan1, Tzu Hsiu Chou1
1Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China. taoyang6-c@my.cityu.edu.hk.
Materials Horizons
|July 22, 2026
Summary
Chemically complex intermetallic alloys (CCIMAs) overcome limitations of traditional alloys. This study developed a new L12-type CCIMA with exceptional strength and ductility for extreme conditions.
Area of Science:
- Materials Science
- Metallurgy
- Solid State Chemistry
Background:
- Conventional intermetallic alloys (IMAs) face compositional limitations.
- Novel multicomponent L12-type chemically complex IMAs (CCIMAs) offer enhanced structural and functional properties for demanding applications like aero-engines.
- Challenges include brittle phase formation due to complex compositions.
Purpose of the Study:
- To address brittle phase formation in L12-type CCIMAs.
- To develop a new L12-type NiCoCrAlTiNbTaB CCIMA with improved strength-ductility synergy and thermal stability.
- To elucidate the relationship between compositional complexity, sublattice site occupancy, and alloy performance.
Main Methods:
- Utilized the valence electron concentration (VEC) and mixing enthalpy (ΔHmix) model for phase formation prediction.
- Investigated the effect of elevated chemical complexity on L12 phase properties, including volume fraction, anti-phase boundary (APB) energy, and nanohardness.
- Analyzed sublattice site occupancy of Al, Ti, Nb, and Ta in the newly designed CCIMA.
Main Results:
- Successfully developed a new L12-type NiCoCrAlTiNbTaB CCIMA with outstanding strength-ductility synergy and thermal stability.
- Demonstrated that increased chemical complexity enhances L12 phase volume fraction, APB energy, and nanohardness.
- Achieved a high APB energy (335.9 ± 13 mJ m⁻²) and yield stress (∼1004 MPa) due to precise sublattice site occupancy.
- Observed a disordered interfacial nanolayer (DINL) that enhances tensile ductility (∼23.7%) and potentially inhibits grain coarsening.
Conclusions:
- The study provides a scientific framework for designing high-performance L12-type CCIMAs.
- Precise control over compositional complexity and sublattice site occupancy is crucial for optimizing integrated performance.
- The developed CCIMA exhibits superior properties suitable for extreme service conditions.
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