An instability index of shear band for plasticity in metallic glasses

✍ Scribed by Z. Han; W.F. Wu; Y. Li; Y.J. Wei; H.J. Gao

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 564 KB
• Volume: 57
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2008.11.018

✦ Synopsis

Catastrophic failure along a dominant shear band sets the limit on how much plasticity can be achieved in metallic glasses (MGs) under uniaxial compression. Here we show that this instability process is governed by a single system parameter, called the shear-band instability index (SBI), which is proportional to sample size and inversely proportional to machine stiffness. We provide extensive experimental proof of this concept by conducting a series of tests with a range of controlled values of sample size and machine stiffness. The theory of SBI has led us to a more comprehensive understanding of the mechanisms of plastic deformation in MGs via simultaneous operation of multiple shear bands versus a single dominant one. This concept provides a theoretical basis to design systems which promote plasticity/ductility in MGs by suppressing or delaying shear-band instability.