Flaw-induced plastic-flow dynamics in bulk metallic glasses under tension

Area of Science:

• Materials Science
• Mechanical Engineering
• Physics of Complex Systems

Background:

• Bulk metallic glasses (BMGs) possess high strength but are prone to sudden failures, especially under tension.
• Understanding plastic flow dynamics is crucial for preventing catastrophic failures in BMGs.
• While critical dynamics are known under compression, tensile plastic flow dynamics in BMGs remain largely unexplored.

Purpose of the Study:

• To investigate the plastic-flow dynamics of bulk metallic glasses (BMGs) under tensile stress.
• To determine if critical dynamics, similar to those observed under compression, can be induced in tensile BMGs.
• To explore methods for achieving stable plastic flow and avoiding catastrophic failures in tensile BMGs.

Main Methods:

• Tensile testing of bulk metallic glasses (BMGs) with introduced flaws.
• Analysis of load drop behavior and its statistical distribution during plastic flow.
• Investigation of stress gradients and stress concentration factors at flaw sites.

Main Results:

• Power-law critical dynamics were observed in the plastic flow of tensile BMGs with introduced flaws.
• Flaw-induced plastic flow under tension exhibited an increasing trend in load drop amplitudes over time.
• A stable plastic-flow stage was achieved, characterized by a power-law distribution of load drops.
• The extent of stable plastic flow correlated positively with the stress concentration factor at the flaw root.

Conclusions:

• Introducing flaws into BMGs under tension can induce power-law critical dynamics and a stable plastic-flow stage.
• The observed phenomenon is attributed to stress gradients around flaw roots.
• These findings offer potential strategies for predicting and mitigating catastrophic failures in tensile BMG applications by manipulating stress fields.