STRESS-STRAIN RELATIONSHIP OF ZR₅₅AL₁₀NI₅CU₃₀ METALLIC GLASS ANALYZED BY 3D IMAGES ON SPHERICAL INDENTS

Mechanically polished surface of Zr₅₅Al₁₀Ni₅Cu₃₀ metallic glass was indented with a rigid ball 0.5 mm in diameter and its corresponding load-depth curve was recorded automatically. Although a stress-strain relationship beneath the indenter can be analyzed from the raw indentation curve, the current analysis developed for crystalline solids can mislead erroneous properties because it does not consider significant material pile-ups in amorphous metallic glasses. Thus, we proposed a novel indent image processing technique for characterizing the contact and flow properties in the metallic glasses; the contact area was measured by differentiating a three-dimensional indent morphology digitized by a surface profiler and a surface-stretching strain was newly defined in order to estimate the flow properties. Finally, the work-hardening index estimated was about 0.05, comparable with the typical value measured from uniaxial compression in the Zr-based metallic glass.