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...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.展开更多
The indentation size effect(ISE)was studied by instrumented nanoindentation and Vickers hardness measurements on polycrystalline copper,βCuAlBe pseudoelastic and age-hardenable CuBe alloys.Variations in the load-dept...The indentation size effect(ISE)was studied by instrumented nanoindentation and Vickers hardness measurements on polycrystalline copper,βCuAlBe pseudoelastic and age-hardenable CuBe alloys.Variations in the load-depth curves at different loads would suggest a change in the behavior of the materials as the load increases.Nanohardness was estimated at different loads taking into account the pile-up in each case,which was estimated from the images of the topography obtained by atomic force microscopy(AFM).The effect of the microstructure of Cu-2Be(wt%)samples on the ISE was also studied.For each copper alloy,the Nix and Gao model was applied to the hardness-depth curves,and significant differences were found for the parameters obtained.Cu is in the constant nanohardness regime for depths below 500 nm,while microhardness exhibits the ISE effect.The behavior of the nanohardness and the plastic strain with the depth is almost inverse.CuAlBe presents the lowest values of plastic strains due to the pseudoelastic effect,while Cu presents an almost constant value around 8%,which corresponds to the highest plastic strain obtained.展开更多
基金supported by Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CICPBA)SECAT (UNCPBA) Argentina
文摘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.
基金This work was financially supported by the Consejo Nacional de Investigaciones Cientfficas y Tecnicas(CONI-CET)the Comision de Investigaciones Cientfficas de la Provincia de Buenos Aires(CICPBA)the SECAT(UNCPBA)Argentina.
文摘The indentation size effect(ISE)was studied by instrumented nanoindentation and Vickers hardness measurements on polycrystalline copper,βCuAlBe pseudoelastic and age-hardenable CuBe alloys.Variations in the load-depth curves at different loads would suggest a change in the behavior of the materials as the load increases.Nanohardness was estimated at different loads taking into account the pile-up in each case,which was estimated from the images of the topography obtained by atomic force microscopy(AFM).The effect of the microstructure of Cu-2Be(wt%)samples on the ISE was also studied.For each copper alloy,the Nix and Gao model was applied to the hardness-depth curves,and significant differences were found for the parameters obtained.Cu is in the constant nanohardness regime for depths below 500 nm,while microhardness exhibits the ISE effect.The behavior of the nanohardness and the plastic strain with the depth is almost inverse.CuAlBe presents the lowest values of plastic strains due to the pseudoelastic effect,while Cu presents an almost constant value around 8%,which corresponds to the highest plastic strain obtained.
