TY - JOUR
T1 - Characterization of free volume changes associated with shear band formation in Zr- and Cu-based bulk metallic glasses
AU - Kanungo, Biraja P.
AU - Glade, Stephen C.
AU - Asoka-Kumar, Palakkal
AU - Flores, Katharine M.
PY - 2004/10
Y1 - 2004/10
N2 - The free volume model for flow in metallic glasses predicts a significant increase in free volume at the onset of plastic deformation. The details of these structural changes are unclear, however, particularly during strain localization in shear bands. In this study, the free volume changes associated with inhomogeneous plastic deformation of a Cu-based bulk metallic glass were examined using positron annihilation spectroscopy (PAS). PAS results indicated that there was a distribution of free volume site sizes in both the as-quenched and rolled glasses, and that the concentration of larger sites increased with deformation. Differential scanning calorimetry was also used to observe the glass transition behaviors of Cu- and Zr-based glasses after rolling and annealing. Annealing resulted in an increase in the height of the endothermic glass transition peak, consistent with structural relaxation relative to the as-quenched material. Deformation resulted in both a lower endothermic peak height and an earlier and deeper exothermic peak associated with structural relaxation, indicating a more disordered structure with more free volume.
AB - The free volume model for flow in metallic glasses predicts a significant increase in free volume at the onset of plastic deformation. The details of these structural changes are unclear, however, particularly during strain localization in shear bands. In this study, the free volume changes associated with inhomogeneous plastic deformation of a Cu-based bulk metallic glass were examined using positron annihilation spectroscopy (PAS). PAS results indicated that there was a distribution of free volume site sizes in both the as-quenched and rolled glasses, and that the concentration of larger sites increased with deformation. Differential scanning calorimetry was also used to observe the glass transition behaviors of Cu- and Zr-based glasses after rolling and annealing. Annealing resulted in an increase in the height of the endothermic glass transition peak, consistent with structural relaxation relative to the as-quenched material. Deformation resulted in both a lower endothermic peak height and an earlier and deeper exothermic peak associated with structural relaxation, indicating a more disordered structure with more free volume.
KW - B. Glasses, metallic
KW - B. Plastic deformation mechanisms
UR - https://www.scopus.com/pages/publications/4544341489
U2 - 10.1016/j.intermet.2004.04.033
DO - 10.1016/j.intermet.2004.04.033
M3 - Article
AN - SCOPUS:4544341489
SN - 0966-9795
VL - 12
SP - 1073
EP - 1080
JO - Intermetallics
JF - Intermetallics
IS - 10-11 SPEC. ISS.
ER -