Nanoindentation Studies of the Effects of Ion Irradiation on the Near Surface Mechanical Response of Annealed Ti₄₀Cu₃₂Pd₁₄Zr₁₀Sn₂Si₂ Metallic Glass Ribbons

Nanoindentation experiments with a Berkovich indenter and a spherical indenter were performed to study the effects of annealing at temperatures below the glass transition temperature and room temperature ion irradiation on the near surface mechanical response of Ti₄₀Cu₃₂Pd₁₄Zr₁₀Sn₂Si₂ metallic glass (MG) ribbons. The specimens were isothermally annealed in vacuum at 573 K and 673 K for 4 hrs. Annealing was seen to increase the hardness of the specimens and decrease their ductility. The annealed specimens were subsequently irradiated by 3.5 MeV Cu²⁺ ions at room temperature using a fluence of 1 × 10¹² ions/cm² or 1 × 10¹⁶ ions/cm². Nanoindentation experiments on the annealed and irradiated specimens showed a reduction in hardness and an increase in ductility for the specimens irradiated at a fluence of 1 × 10¹² ions/cm². Although the values of the mean contact pressure and critical shear stress under the spherical indenter showed an easier formation of shear bands after irradiation, increasing the irradiation fluence to 1 × 10¹⁶ ions/cm² was seen to increase the hardness value and decrease the ductility of the specimens.