Correlation between crystallization and strain hardening during homogeneous deformation of Cu54Ni6Zr22Ti18 bulk metallic glass

Homogeneous deformation behaviors of the Cu54Ni6Zr22Ti18 BMGs with fully amorphous structure (FA) and with high density of ordered domains (OD) in amorphous matrix were examined and compared. Strain rate vs. stress curves showed that the OD exhibited m = 0.5 at low strain rates and m < 0.5 at high strain rates whereas the FA exhibited m ∼ 1 at low strain rates and m < 0.5 at high strain rates. The degree of strain hardening measured from the stress-strain curves of the FA could be correlated with the volume fraction of crystalline phase measured by differential scanning calorimetry. This result allows prediction of the volume fraction of crystallized phase in amorphous matrix and the strength ratio between nanocrystalline phase and amorphous matrix at a given volume fraction.