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Your search keyword '"Jácome Leonardo Agudo"' showing total 11 results
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2. Electron-beam-induced modification of gold microparticles in an SEM

Author

Weinel, Kristina, Hahn, Marc Benjamin, Lubk, Axel, Feng, Wen, Martinez, Ignacio Gonzalez, Büchner, Bernd, and Jácome, Leonardo Agudo

Subjects
Condensed Matter - Materials Science
Abstract

Electron-beam-induced conversion of materials in a transmission electron microscope uses the high power density of a localized electron beam of acceleration voltages above 100 kV as an energy source to transform matter at the sub-micron scale. Here, the e-beam-induced transformation of precursor microparticles employing a low-energy e-beam with an acceleration voltage of 30 kV in a scanning electron microscope is developed to increase the versatility and efficiency of the technique. Under these conditions, the technique can be classified between e-beam lithography, where the e-beam is used to mill holes in or grow some different material onto a substrate, and e-beam welding, where matter can be welded together when overcoming the melting phase. Modifying gold microparticles on an amorphous SiOx substrate reveals the dominant role of inelastic electron-matter interaction and subsequent localized heating for the observed melting and vaporization of the precursor microparticles under the electron beam. Monte-Carlo scattering simulations and thermodynamic modeling further support the findings.

Published
2024

10. Transmission electron microscopy study of the microstructural evolution during high-temperature and low-stress (011) [011] shear creep deformation of the superalloy single crystal LEK 94.

Author

Jácome, Leonardo Agudo, Göbenli, Gülcan, and Eggeler, Gunther

Subjects
HEAT resistant alloys, TRANSMISSION electron microscopy, METAL microstructure, EFFECT of temperature on metals, STRAINS & stresses (Mechanics), SHEAR (Mechanics), METAL creep, SINGLE crystals
Abstract

The present work describes the shear creep behavior of the superalloy LEK 94 at temperatures between 980 and 1050 °C and shear stresses between 50 and 140 MPa for loading on the macroscopic crystallographic shear system (MCSS) (011)[011]. The strain rate versus strain curves show short primary and extended secondary creep regimes. We find an apparent activation energy for creep of Qapp 5 466 kJ/mol and a Norton-law stress exponent of n 5 6. With scanning transmission electron microscopy, we characterize three material states that differ in temperature, applied stress, and accumulated strain/time. Rafting develops perpendicular to the maximum principal stress direction, γ channels fill with dislocations, superdislocations cut γ' particles, and dislocation networks form at γ/γ' interfaces. Our findings are in agreement with previous results for high-temperature and low-stress [001] and [110] tensile creep testing, and for shear creep testing of the superalloys CMSX-4 and CMSX-6 on the MCSSs (111)[011] and (001)[100]. The parameters that characterize the evolving γ/γ' microstructure and the evolving dislocation substructures depend on creep temperature, stress, strain, and time. [ABSTRACT FROM AUTHOR]

Published
2017
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