Creep Behavior and Its Influencing Factors in High-Entropy Superalloys: A Molecular Dynamics Simulation Study

Area of Science:

• Materials Science
• Mechanical Engineering
• Computational Materials Science

Background:

• Turbine blades in aero-engines require materials with exceptional mechanical performance under extreme thermomechanical cyclic loading.
• High-entropy superalloys (HESAs) with a stable dual-phase γ/γ' microstructure offer promising high-temperature structural material properties, particularly superior creep resistance.

Purpose of the Study:

• To systematically investigate the creep behaviors of high-entropy superalloys.
• To explore the influence of stress, temperature, γ/γ' lattice misfit, and γ' volume fraction on creep deformation mechanisms using molecular dynamics simulations.

Main Methods:

• Molecular dynamics (MD) simulations were employed to study creep deformation.
• Systematic variation of stress, temperature, lattice misfit, and volume fraction of the γ' phase.
• Microstructural analysis and atomic diffusion data were utilized to understand creep mechanisms.

Main Results:

• Temperature has a more dominant effect on creep behavior than stress.
• Increasing stress shifts the dominant creep mechanism from atomic diffusion to dislocation nucleation/motion and phase transformation.
• Creep resistance is critically dependent on γ/γ' lattice misfit and γ' volume fraction; negative misfit and increased γ' volume fraction enhance creep resistance.
• Structural stability of the γ/γ' dual-phase system is closely linked to creep resistance.

Conclusions:

• High-entropy superalloys exhibit tunable creep resistance influenced by operational conditions and microstructural parameters.
• Optimizing lattice misfit and γ' volume fraction is crucial for enhancing the high-temperature performance of these alloys.
• Findings provide insights for designing advanced high-entropy superalloys for demanding aero-engine applications.