Influence of pile-up on nanoindentation measurements in Cu-2wt.%Be samples with precipitates
(1. IFIMAT, Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires,Pinto 399, 7000 Tandil, Argentina;
2. Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Av. Rivadavia 1917,
C1033AAJ Buenos Aires, Argentina;
3. CIFICEN (UNCPBA-CICPBA-CONICET), Pinto 399, 7000 Tandil, Argentina;
4. Comisión de Investigaciones Científicas de la Provincia de Bs. As., Calle 526 entre 10 y 11, 1900 La Plata, Argentina)
2. Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Av. Rivadavia 1917,
C1033AAJ Buenos Aires, Argentina;
3. CIFICEN (UNCPBA-CICPBA-CONICET), Pinto 399, 7000 Tandil, Argentina;
4. Comisión de Investigaciones Científicas de la Provincia de Bs. As., Calle 526 entre 10 y 11, 1900 La Plata, Argentina)
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.
Key words: pile-up; nanoindentation measurement; copper alloy; precipitation; microstructure; mechanical properties