When Atoms Choose Their Neighbors: Element-Specific Views of Local Chemical Order in High-Entropy Alloys

Area of Science:

• Materials Science
• Condensed Matter Physics
• Analytical Chemistry

Background:

• Local chemical order (LCO) is crucial for understanding high-entropy alloys (HEAs) but is challenging to quantify.
• Existing methods struggle to provide element-specific, quantitative LCO data in complex alloy systems.

Purpose of the Study:

• To demonstrate how X-ray absorption spectroscopy (XAS) can quantitatively probe LCO in HEAs.
• To provide practical guidelines for XAS data acquisition and analysis for LCO determination.
• To explore the emergence of single-atom and near-single-atom motifs in HEAs.

Main Methods:

• Utilized X-ray absorption spectroscopy (XAS) for element-specific LCO analysis.
• Developed a coordination-number-based framework for LCO quantification.
• Analyzed model HEAs to observe LCO evolution with increasing component number.

Main Results:

• XAS successfully provided quantitative, element-specific insights into LCO in complex HEAs.
• A coordination-number framework effectively analyzed LCO, revealing single-atom and near-single-atom motifs.
• The study bridges the understanding between HEAs and single-atom alloys.

Conclusions:

• XAS is a powerful tool for quantifying LCO in HEAs.
• Standardized protocols, uncertainty quantification, and advanced XAS techniques (operando, time-resolved) are priorities for future research.
• Integration with other characterization and modeling techniques will enhance LCO analysis.