Plasticity and structural instability in a bulk metallic glass deformed inthe supercooled liquid region

The deformation behavior of a bulk amorphous Zr-10Al-5Ti-17.9Cu-14.6Ni allo y was characterized in the supercooled liquid re.-ion, The alloy was observ ed to exhibit Newtonian behavior at low strain rates but to become non-Newt onian at high strain rates. Structures of the amorphous material, both befo re and after deformation, were examined using X-ray diffraction and high-re solution electron microscopy. Experimental results showed the presence of n anocrystallites in the deformed samples, suggesting that the non-Newtonian behavior,vas associated with the concurrent crystallization of the amorphou s structure during deformation; that is, a mixed crystalline-plus-amorphous structure was being tested. A mechanistic model based upon structural evol ution has been developed to interpret the observed non-Newtonian behavior. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.