Yielding in crystalline metals is well known to be governed by dislocation dynamics; however, the structural origin of yielding in metallic glasses (MGs) still remains as an issue of intense debate despite that substantial research efforts have been expended. In this Letter, based on well-designed cyclic microcompression tests, we provide compelling experimental evidence revealing that yielding of MGs is essentially a stress-induced viscous flow process, during which the measured viscosity ranges from 1011 Pa s to I011 Pa s and decreases with the increase of applied stress, resembling the "shear- Thinning" behavior of non-Newtonian liquids. This stress-induced non-Newtonian Mow finally leads to shear instability, which manifests itself as the phenomenon of delayed yielding common to a variety of MGs.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)