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Indexed by:Journal Papers

Date of Publication:2015-09-01

Journal:METALS

Included Journals:SCIE、Scopus

Volume:5

Issue:3

Page Number:1188-1196

ISSN No.:2075-4701

Key Words:bulk metallic glass; serrated flow; plasticity; self-organized critical behavior

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 x 10(-2), 2 x 10(-3), and 2 x 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 x 10(-2)s(-1). However, the medial state occurs at the strain rates of 2 x 10(-3)s(-1), and eventually the self-organized critical (SOC) behavior appears at the strain rate of 2 x 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 x 10(-4)s(-1). The values of the goodness of fit are 0.95 and 0.99 at the strain rates of 2 x 10(-3) and 2 x 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.