Influence of the load on the elastic modulus determined from nanoindentation measurements in a Cu-2Be alloy with different microstructures

Abstract

The influence of the load on the elastic modulus in a polycrystalline age-hardenable Cu-2Be (wt%) alloy with different microstructures was studied. Nanoindentation measurements were carried out on homogenized samples (α phase), aged for 1 h at 400 °C(α phase with γ' precipitates) and aged for 10 h at 400 °C(α phase with γ precipitates). A sample of αCu was also studied to compare its behavior with the values of the Cu-2Be specimens. The surface of the samples after unloading was analyzed byAFM images and the specimens with nanoprecipitates showed the presence of pile-up. The elastic modulus was estimated from the load-depth curves carried out at different maximum loads, using the Oliver and Pharr method and the method of the indentation work. From the Oliver and Pharr method, the modulus decreases with increasing maximum load, but this variation is reduced using the estimation by the indentation work method in some of the studied samples. Even so, a dependence of the modulus with the load is observed, especially in theα Cu-2Be sample and in the sample with γ' nanoprecipitates.