Relaxation processes and physical aging in metallic glasses.

Area of Science:

• Materials Science
• Physics
• Condensed Matter Physics

Background:

• Metallic glasses, discovered in the 1960s, possess unique properties with potential applications in medicine, environmental science, and engineering.
• Their widespread commercial use is hindered by temporal instability and physical aging, which degrade mechanical properties, leading to embrittlement and failure.

Purpose of the Study:

• To review the current state of experimental advances in probing physical aging and relaxation processes in metallic glasses.
• To highlight similarities and differences between metallic glasses and other hard and soft matter glasses.
• To provide a multiscale approach, connecting macroscopic studies with microscopic investigations.

Main Methods:

• Review of experimental advances in probing physical aging and relaxation in metallic glasses.
• Multiscale analysis connecting macroscopic observations with microscopic investigations.
• Emphasis on distinct relaxation processes in viscous melts and their behavior in the glassy state.

Main Results:

• Physical aging in metallic glasses involves irreversible atomic-scale processes like avalanches and intermittent dynamics.
• These dynamics are linked to a complex energy landscape with numerous metastable glassy states.
• Distinct relaxation processes beyond the main structural relaxation are observed in metallic melts and glasses.

Conclusions:

• Understanding and controlling physical aging is critical for advancing metallic glasses as structural materials.
• Physical aging involves complex out-of-equilibrium dynamics at the atomic scale.
• Future research should focus on experimental challenges and comparisons with theoretical/numerical simulations.