What is the reason of size effect on the hardness and reduced modulus of melt-spun Al-12Si-0.5Sb alloy in the indentation test?


In this study, the mechanical properties of melt-spun Al-12Si-0.5Sb alloy were analysed by nanoindentation technique. Scanning electron microscopy observations exhibited that the alloy has a fine-grained eutectic microstructure. Differantial scanning calorimetry analysis revealed two exhotermic reaction peaks which were identifed as supersatured Si atoms in Al matrix. In nanoindentation analysis, a series of loads ranging from 0.5 to 300 mN was applied to the alloy surface to obtain load-depth curves. Two mechanical properties, namely hardness and reduced elastic modulus of alloy, were calculated by Oliver-Pharr approach. Mechanical properties exhibited size dependency, which was called indentation size effect. This phenomenon was evaluated by Nix-Gao and Korsunsky models. It was found that the Korsunsky model was compatible with the data and the hardness values obtained from this model were close to the literature values.

Korsunsky model, alloys