Tuning element distribution, structure and properties by composition in high-entropy alloys

Area of Science:

• Materials Science
• Metallurgy
• Nanotechnology

Background:

• High-entropy alloys (HEAs) offer unique mechanical properties due to their complex compositions.
• Understanding composition-structure-property relationships is crucial for HEA design.
• Atomic-scale element distribution significantly impacts material behavior.

Purpose of the Study:

• To investigate the atomic-scale element distribution in face-centred cubic (FCC) high-entropy alloys.
• To compare the Cantor alloy (CrMnFeCoNi) with a new FCC alloy (CrFeCoNiPd).
• To correlate element distribution with mechanical properties and deformation mechanisms.

Main Methods:

• Atomic-resolution chemical mapping to analyze element distribution.
• In situ transmission electron microscopy (TEM) during straining experiments.
• Analysis of dislocation glide, cross-slip, and interactions.

Main Results:

• The CrFeCoNiPd alloy shows significant element aggregation (1-3 nm wavelength) compared to the uniform Cantor alloy.
• Nanoscale strain fields in CrFeCoNiPd impede dislocation glide.
• CrFeCoNiPd exhibits massive dislocation cross-slip and strong dislocation interactions.
• CrFeCoNiPd demonstrates higher yield strength with maintained strain hardening and ductility.

Conclusions:

• Pronounced composition fluctuations and increased stacking-fault energy in CrFeCoNiPd drive unique deformation mechanisms.
• Atomic-scale element mapping provides insights for designing HEAs with superior mechanical performance.
• Tailoring composition and atomic configurations is key to achieving outstanding material properties.