Constitutive model for inhomogeneous flow in bulk metallic glasses

✍ Scribed by Alban Dubach; Florian H. Dalla Torre; Jörg F. Löffler

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 669 KB
• Volume: 57
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2008.10.027

✦ Synopsis

This study presents results on the mechanical properties of Zr-based bulk metallic glasses over a wide range of temperatures (77-673 K) and strain rates (3.3 Â 10 À5 À 0.2 s À1 ), and provides novel information on the kinetics of inhomogeneous deformation in metallic glasses. The disappearance of serrated flow, i.e. temporal homogenization, below a critical temperature and above a critical strain rate corresponds to a transition of the asymptotic strain rate sensitivity (SRS) from negative to positive values. Based on thermally activated shear processes a temperature and strain rate dependent deformation model is presented that includes a time-varying state variable which represents the local degree of relaxation in the shear band after a shear event has taken place. The model makes possible a theoretical description of the observed SRS and the spatio-temporal evolution of plastic deformation in metallic glasses.