Papers by Keyword: Electron Tomography

Abstract: The present work describes a methodology to implement microstructural data obtained from TEM tomography into finite element (FE) simulation software. In this first approach the tomographic reconstruction is treated with different software to create a 3D realistic model of the microstructure of the composite. This realistic model is compared against 2D image-based models via FE simulations in order to compare the mechanical behavior achieved with both procedures. After this first study the results obtained with both types of model are similar. These results are a promising starting point for the development of this novel methodology for obtaining nanocomposite FE models from TEM tomography with realistic results.

Abstract: Y_1-xGd_xBa₂Cu₃O_7-y film with BaZrO₃ was fabricated on CeO₂ buffered LaMnO₃/ion beam assisted deposition MgO/Gd₂Zr₂O₇/Hastelloy C276^TM substrates by the trifluoroacetates metal organic deposition process, whose microstructural and elemental analyses were performed by transmission electron microscopy. Y_1-xGd_xBa₂Cu₃O_7-y film with the thickness about 700 nm was found composed of c-axis oriented grains and large numbers of randomly oriented precipitates, such as (Y,Gd)₂Cu₂O₅, CuO and BaZrO₃. (Y,Gd)₂Cu²O⁵ and CuO precipitates were heterogeneously dispersed in the Y_1-xGd_xBa₂Cu₃O_7-y matrix with their sizes ranging between 100 and 200 nm, and BaZrO₃ precipitates were uniformly dispersed with their sizes ranging between 10 and 20 nm. Electron tomography with elemental information was performed further to reveal the three-dimensional information of BaZrO3 precipitates.

Abstract: Quantitative analysis of γ' and γ" phase nanoparticles in Inconel 718 was performed using FIB-SEM tomography. Three-dimensional visualisation showed that γ' particles are spherical, while γ" precipitates are disc-shaped. The dependence of the particle size of both phases on the heat treatment applied was detected. It was proven that the FIB-SEM tomography is a very precise method for metrology and morphology investigation of nanoparticles precipitated in Inconel 718 superalloy.

Abstract: This paper covers the analysis of amorphous alloys CoP-CoNiP system by means of high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy and electron tomography. The last years have seen a sufficient progress in the analysis of nanomaterials structure with the help of high resolution tomography. This progress was motivated by the development of microscopes equipped with aberration correctors and specialized sample holders which allow reaching the tilts angles up to ±80°. The opportunities delivered by the method of electron tomography sufficiently grow when producing high resolution images and using chemical analysis, such as X-Ray energy-dispersive microanalysis and electron energy loss spectroscopy (EELS).

Abstract: In the present work a quantitative analysis of γ' and γ" phase nanoparticles in Inconel 718 was performed using two methods of electron tomography, namely EFTEM and FIB tomography. 3D visualisation showed that γ' particles are spherical, while γ" precipitates are disc-shaped. The values of mean size of γ' and γ" phase particles, determined by both electron tomography methods applied, are in good agreement.

Abstract: Three-dimensional (3D) observation of Pt nanoparticles on the surface of carbon nanoparticles, one of the important catalyst systems for energy storage such as fuel cells, was carried out by using an electron tomography system attached to a transmission electron microscope (TEM). In the Pt/carbon sample preparation process, pristine and graphitized carbon nanospheres (CNSs, 200 nm average diameter) were immersed into H2PtCl6 solution, followed by a heat-treatment at 493 K. According to the electron tomography technique, we confirmed that crystalline Pt particles (2-3 nm) were homogeneously dispersed on the whole surface of pristine CNSs, while on the graphitized CNSs Pt was aggregated on the ridgeline of the polyhedronized CNS particles or on the connecting surface between two CNS particles. Dependence of Pt dispersion as shown was discussed with the distribution of surface defects of CNS particles.

Abstract: Electron tomography has developed into a powerful technique to image the 3D structure of complex materials with nanometer resolution. Both, TEM and HAADF-STEM tomography exhibit tremendous possibilities to visualize nanostructured materials for a wide range of applications. Electron tomography is not only a qualitative tool to visualize nano¬structures, but recently electron tomographic results are also exploited to obtain quantitative measurements in 3D. We evaluated the reconstruction and segmentation process for a heterogeneous catalyst and, in particular, tried to assess the reliability and accuracy of the quantification process. Furthermore, a quantitative analysis of electron tomographic results was compared to macroscopic measurements.

Abstract: Crack tip dislocations and dislocations introduced by three point-bending tests at high temperature are observed by combinating scanning transmission electron microscopy and computed tomography (STEM-CT). Commercially available P type (001) single crystal silicon wafers were employed. A series of STEM image was acquired from -60º to +60º in tilt range with 2º in tilt step. The diffraction vector was maintained close to g(hkl) = 220 during the acquisition by adjusting the [110] direction of the sample parallel to the tilt axis of the holder. Reconstructed images of dislocations revealed dislocation structures in three-dimension.

Abstract: This paper generally presents different techniques available to image the microstructure of materials in three dimensions (3D) at different scales. It then focuses on the use of the more versatile of these techniques for aluminum alloys : X-ray tomography. The paper describes the recent improvements (spatial and the temporal resolution, grain imaging). Electron tomography is also presented as a promising technique to improve the spatial resolution.

Abstract: . Generally rubber products are a typical soft material, and a composite of a nano-filler (typically, carbon black or particulate silica) and a rubber (natural rubber and various synthetics are used). The properties of these soft nano-composites have been well known to depend on the dispersion of the nano-filler in the rubbery matrix. The most powerful tool for the elucidation of it has been transmission electron microscopy (TEM). The microscopic techniques are based on the projection of 3-dimensional (3D) body on a plane (x, y plane), thus the structural information along the thickness (z axis) direction of the sample is difficult to obtain. This paper describes our recent results on the dispersion of carbon black (CB) and particulate silica in natural rubber (NR) matrix observed by TEM combined with electron tomography (3D-TEM) technique, which enabled us to obtain images of 3D nano-structure of the sample. Thus, 3D images of CB and silica in NR matrix are visualized and analyzed in this communication. These results are precious ones for the design of soft nano-composites, and the technique will become an indispensable one in nanotechnology.