Realistic microstructure evolution of complex Ta-Nb-Hf-Zr high-entropy alloys by simulation techniques

Area of Science:

• Materials Science
• Computational Materials Science
• Alloy Design

Background:

• High-entropy alloys (HEAs) and complex concentrated alloys (CCAs) are recognized for their exceptional properties.
• Predicting the nanoscale structural features and thermodynamic behavior of HEAs remains a challenge.

Purpose of the Study:

• To develop and validate a novel simulation methodology for predicting the nanometer-level local structural features of complex HEAs.
• To quantitatively assess the morphology, atomic composition, and thermodynamic aspects of short-range clustering (SRCs) in Ta$_{0.25}$Nb$_{0.25}$Hf$_{0.25}$Zr$_{0.25}$ HEA.
• To demonstrate the potential of computational methods in accelerating materials development by reducing experimental characterization needs.

Main Methods:

• Creation of an 11664-atom alloy structure model.
• Application of a hybrid Monte Carlo and molecular dynamics (MC/MD) approach for structure evolution at 1800°C.
• Validation of simulation results against experimental data including HRTEM, APT, and synchrotron X-ray diffraction.

Main Results:

• The simulation methodology realistically predicts the morphology and quantitative atomic composition of SRCs at the nanoscale.
• The developed MC/MD approach successfully reproduces experimental material characterization results, including microstructure and local chemical compositions.
• The simulation method operates independently of experimental input for evolving SRCs, offering a purely computational approach.

Conclusions:

• The proposed simulation methodology accurately captures the nanoscale structural intricacies of complex HEAs.
• Computational methods like MC/MD can significantly reduce the reliance on extensive experimental characterizations.
• This work highlights the potential of advanced simulation techniques to accelerate the discovery and development of novel HEAs.