Creep behavior of a Fe-based bulk amorphous alloy using nanoindentation

Abstract

The creep behavior of a {［（Fe0.6Co0.4）0.75B0.2Si0.05］0.96Nb0.04}96Cr4 bulk amorphous alloy and effects of different loading rates on its creep deformation behavior were investigated using nanoindentation technique at room temperature. It is found that the creep deformation of this alloy is strongly dependent on the indentation loading rate: when the loading rate ranges from 3 to 24 mN/s, distinct creep deformation occurs; but when the loading rate decreases to 1 mN/s or 0.75 mN/s, the creep deformation is completely suppressed. The creep deformation behavior of the {［（Fe0.6Co0.4）0.75B0.2Si0.05］0.96Nb0.04}96Cr4 bulk amorphous alloy was modeled using the elastic-viscoelastic-viscous （EVEV） model and a high correlation coefficient （R） of 0.9392 was obtained, implying that this creep behavior studied can be well described by the EVEV model. Based on the EVEV model, the creep compliance and retardation spectrum, which are related to the interior structure of the bulk amorphous alloy, were further calculated by the EVEV model. Finally, the creep mechanism at room temperature was discussed in detail according to the analysis of the creep rate sensitivity index （m） as well as the observation on the morphology of indents using the atomic force microscope （AFM）.