The Self-Organized Critical Behavior in Pd-based Bulk Metallic Glass

Zhong Wang,Jiaojiao Li,Baocheng Wang,Wei Zhang,Junwei Qiao

doi:10.3390/met5031188

Zhong Wang, Jiaojiao Li + Show 3 more

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https://doi.org/10.3390/met5031188

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Abstract

Bulk metallic glasses (BMGs) deform irreversibly through shear banding manifested as serrated-flow behavior during compressive tests. The strain-rate-dependent plasticity under uniaxial compression at the strain rates of 2 × 10−2, 2 × 10−3, and 2 × 10−4·s−1 in a Pd-based BMG is investigated. The serrated flow behavior is not observed in the stress-strain curve at the strain rate of 2 × 10−2·s−1. However, the medial state occurs at the strain rates of 2 × 10−3·s−1, and eventually the self-organized critical (SOC) behavior appears at the strain rate of 2 × 10−4·s−1. The distribution of the elastic energy density shows a power-law distribution with the power-law exponent of −2.76, suggesting that the SOC behavior appears. In addition, the cumulative probability is well approximated by a power-law distribution function with the power-law exponent of 0.22 at the strain rate of 2 × 10−4·s−1. The values of the goodness of fit are 0.95 and 0.99 at the strain rates of 2 × 10−3 and 2 × 10−4·s−1, respectively. The transition of the dynamic serrated flows of BMGs is from non-serrated flow to an intermediate state and finally to the SOC state with decreasing the strain rates.

Highlights

Bulk metallic glasses (BMGs) have attracted significant scientific and technological attention, since they exhibit extraordinarily high strengths about two times or even higher than that of their crystalline counterparts at ambient temperature, due to the absence of dislocations [1,2]
The Pd75Si15Ag3Cu7 BMG exhibits only one major exothermic event, indicating that this alloy is located near a Pd–Si–Ag–Cu eutectic point, which means that the high glass formation ability occurs and the critical diameter is 10 mm [21]
The serrations occur on the stress-strain curve, it is treated as non-serrated-flow behavior at the strain rate of 2 ×10−2·s−1, which is not discussed in the current research

Summary

Introduction

Bulk metallic glasses (BMGs) have attracted significant scientific and technological attention, since they exhibit extraordinarily high strengths about two times or even higher than that of their crystalline counterparts at ambient temperature, due to the absence of dislocations [1,2]. Their use as structural materials is severely limited because of their poor ductility and catastrophic failure at room temperature arising from the shear localization [3,4]. BMGs at different strain rates during serrated flows are investigated by statistical dynamical analysis

Experimental Procedures

Results and Discussion

Conclusions