Unveiling the Structural Origins of Dynamic Diversity in Pd-Based Metallic Glasses

Area of Science:

• Materials Science
• Condensed Matter Physics
• Amorphous Materials

Background:

• β-relaxation is a key dynamic behavior in metallic glasses (MGs), but its structural origins remain poorly understood.
• Understanding β-relaxation is crucial for predicting the overall dynamics and aging behavior of MG systems.
• Previous research has not fully elucidated the distinct dynamic features observed across different MG compositions.

Purpose of the Study:

• To investigate the distinct β-relaxation behaviors in two palladium-based metallic glasses: Pd─Cu─P and Pd─Ni─P.
• To elucidate the underlying structural origins responsible for the differing dynamic characteristics.
• To correlate atomic dynamics with microscopic structures to understand aging phenomena in disordered materials.

Main Methods:

• Utilized advanced X-ray photon correlation spectroscopy (XPCS) and X-ray absorption fine structure (XAFS) techniques.
• Performed first-principles calculations to complement experimental findings.
• Analyzed atomic mobility and local structural environments in the metallic glass samples.

Main Results:

• Pd─Cu─P metallic glass exhibits pronounced β-relaxation and fast atomic dynamics, attributed to high copper atom mobility and locally favored structures.
• Pd─Ni─P metallic glass shows weakened β-relaxation and sluggish dynamics, due to nickel atom motion being constrained by phosphorus atoms.
• A clear correlation was established between atomic dynamics and microscopic structural features.

Conclusions:

• The mobility of constituent atoms (Cu vs. Ni) and their interactions with network-forming atoms (P) dictate the β-relaxation behavior in these metallic glasses.
• This study provides a fundamental understanding of the structural origins of diverse dynamic behaviors in metallic glasses.
• The findings offer insights into the nature of aging in disordered materials by linking dynamics to structure.