Influence of pile-up on nanoindentation measurements in Cu–2wt.%Be samples with precipitates

Abstract

The influence of pile-up on the nanoindentation measurements in Cu–2wt.%Be samples with precipitates was carefully studied. The precipitates were formed by aging treatments for 1 h at different temperatures between 540 and 680 K. The load–depth curves were analyzed using the classical Oliver and Pharr method, and the obtained elastic modulus and hardness were compared with values estimated by other techniques. An important level of pile-up was found in samples with precipitates and differences in the load–depth curves were observed between the unaged and aged samples. A correction of the contact depth considering the pile-up proposed by Loubet was used for hardness estimation. For the determination of the elastic modulus, an approach based on the relation between the ratio of unloading work to indentation total work, with the ratio H/Er (H is the hardness; Er is the reduced modulus), was employed. A specific relation between both parameters was developed.