Effects of annealing and deformation on structural rearrangement of a Zr-based bulk metallic glass

The structural changes of a Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass (BMG) have been investigated by examining the nanostructures formed during thermal treatments and deformation. The structural states were examined by using an Extended X-ray Absorption Fine Structure (EXAFS) as well as a differential scanning calorimetry (DSC). Annealing treatment at 643 K for 680 s produced only a small structural relaxation. A deformation induced structural disordering (DISD) was, on the other hand, observed at an initial state of a non-Newtonian flow (e=0.03 and 0.076) appearing with the stress overshoot. By increasing the test temperature to 673 K, an intermediate temperature range in an undercooled liquid state, structural relaxation appeared to saturate in both the annealed and deformed specimens. In a Newtonian viscous flow region, the DISD phenomenon was, however, observed only after deforming to 3 % strain and then disappeared rapidly in a steady-state flow region without a stress overshoot.