The hardness and Young's modulus of barrier-type, amorphous anodic oxides have been determined by nanoindentation. The procedure used shallow indents, of 55 nm depth, with alumina, tantala and alumina/tantala `mixed oxide' films of about 500 nm thickness. The results revealed respective hardnesses of approximately 7.0, 5.3 and 6.5 GPa, and respective Young's moduli of approximately 122, 140 and 130 GPa. Thus, the hardness and Young's modulus followed opposite trends, with alumina having the highest hardness and lowest modulus, and the `mixed oxide' having intermediate properties. The hardness and Young's modulus of amorphous alumina are factors of about 3.1-3.7 times lower than those of crystalline aluminas.

Nanoindentation tests of Pd 40 Cu 30 Ni 10 P 20 bulk metallic glass were performed over a wide range of indentation rates (from 0.04 up to 6.4 mN s −1 ) under the standard load control mode. New results using the feedback displacement control mode are also presented. The dependence of the pop-in formation on the loading rate is investigated. Variations in hardness and reduced elastic modulus as a function of the indentation rate are observed. A softening effect occurs when increasing the loading rate. This is explained by the differences in plastic deformation achieved at different indentation rates. The displacement control mode was used to avoid the shear localization of the free volume, leading to the almost complete absence of pop-ins along the loading curve. The obtained results suggest that plastic flow in bulk metallic glasses is governed by the rate of creation of free volume, which depends on the strain rate and its localization into shear bands.

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