Carbon Micro-Alloying Promotes Creep Flow via Enhanced Structural Heterogeneity in Fe-Based Amorphous Alloys

TL;DR

Adding carbon to iron-based amorphous alloys increases structural heterogeneity, which enhances creep flow and mechanical behavior.

Contribution

The study establishes a direct link between carbon micro-alloying, structural heterogeneity, and improved mechanical performance in metallic glasses.

Findings

Carbon micro-alloying lowers crystallization temperature and increases β-relaxation in Fe-based amorphous alloys.

Nanoindentation creep analysis shows broader relaxation-time distributions with carbon addition.

Carbon-rich samples exhibit more liquid-like regions and viscoelastic heterogeneity, promoting creep flow.

Abstract

Tuning structural heterogeneity in metallic glasses is key to improving their mechanical performance. Here we examine how carbon micro-alloying modulates the relaxation dynamics and creep of Fe-based amorphous ribbons. Increasing carbon content lowers the crystallization temperature, amplifies β-relaxation, and reduces hardness, consistent with enhanced atomic mobility. Nanoindentation creep, fitted with a stretched-exponential model, shows a decreasing exponent with carbon addition, indicating broader relaxation–time distributions and stronger dynamic heterogeneity. Nanoscale force-mapping further reveals a larger fraction of liquid-like regions and pronounced viscoelastic heterogeneity in carbon-rich samples. These changes facilitate the activation of shear-transformation zones and promote room-temperature creep flow. Together, the results establish a direct link between structural heterogeneity, relaxation processes, and mechanical response, providing guidance for the design of ductile metallic glasses.

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