Rate-dependent serrated flow and plastic deformation in Ti₄₅Zr₁₆Be₂₀Cu₁₀Ni₉bulk amorphous alloy during nanoindentation

Abstract

The plastic deformation of Ti 45 Zr 16 Be 20 Cu 10 Ni 9 bulk metallic glass has been investigated by nanoindentation performed with loads ranging from 10 to 200 mN in a wide range of loading rates. The plastic flow in the alloy exhibited conspicuous serrations at low loading rates. The serrations, however, became less prominent as the rate of indentation increased. Atomic force microscopy showed a significant pile-up of materials around the indents, indicating that a highly localized plastic deformation occurred under nanoindentation. The possible mechanism governing the plastic deformation in bulk metallic glass specimens is tentatively discussed in terms of strain-induced free volume.