Sample size effects on strength and deformation mechanism of Sc₇₅Fe₂₅ nanoglass and metallic glass

The mechanical properties and deformation mechanism of Sc₇₅Fe₂₅ nanoglass and Sc₇₅Fe₂₅ metallic glass pillars with diameter from 2 μm to 95 nm were investigated by means of ex-situ and in-situ compression tests. The results showed that the yield strength and deformation mechanism in the metallic glass were size-dependent while these in the nanoglass were not. It is suggested that the reduced shear band nucleation sites in metallic glass with decreasing sample size results in the increased yield strength and transition of deformation mode. In contrast, the glass/glass interfaces in nanoglass which have reduced density could serve as shear band nucleation sites and therefore promote multiple shear banding. - Graphical abstract: Nanoglasses were a new type of amorphous materials and their microstructure consists of glassy regions ("grains") with average size of ~ 10 nm and glass/glass interfaces (GGIs) between these glassy grains with widths of ~ 1 nm. A locally reduced density in the GGIs relative to the density of the glassy grains indicates that the GGIs in nanoglasses have an atomic structure which deviates from the rapidly-quenched metallic glass. For nanoglass, the existence of a large number of GGIs benefits for shear band nucleation and the subsequent multiple shear banding. While for submicron MG sample, there is not enough free space among the shear band nuclei for growing into a mature shear band.