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Summary: Combined focused ion beam and scanning electron microscope (FIB‐SEM) tomography is a well‐established technique for high resolution imaging and reconstruction of the microstructure of a wide range of materials. Segmentation of FIB‐SEM data is complicated due to a number of factors; the most prominent is that for porous materials, the scanning electron microscope image slices contain information not only from the planar cross‐section of the material but also from underlying, exposed subsurface pores. In this work, we develop a segmentation method for FIB‐SEM data from ethyl cellulose porous films made from ethyl cellulose and hydroxypropyl cellulose (EC/HPC) polymer blends. These materials are used for coating pharmaceutical oral dosage forms (tablets or pellets) to control drug release. We study three samples of ethyl cellulose and hydroxypropyl cellulose with different volume fractions where the hydroxypropyl cellulose phase has been leached out, resulting in a porous material. The data are segmented using scale‐space features and a random forest classifier. We demonstrate good agreement with manual segmentations. The method enables quantitative characterization and subsequent optimization of material structure for controlled release applications. Although the methodology is demonstrated on porous polymer films, it is applicable to other soft porous materials imaged by FIB‐SEM. We make the data and software used publicly available to facilitate further development of FIB‐SEM segmentation methods. Lay Description: For imaging of very fine structures in materials, the resolution limits of, e.g. X‐ray computed tomography quickly become a bottleneck. Scanning electron microscopy (SEM) provides a way out, but it is essentially a two‐dimensional imaging technique. One manner in which to extend it to three dimensions is to use a focused ion beam (FIB) combined with a scanning electron microscopy and acquire tomography data. In FIB‐SEM tomography, ions are used to perform serial sectioning and the electron beam is used to image the cross section surface. This is a well‐established method for a wide range of materials. However, image analysis of FIB‐SEM data is complicated for a variety of reasons, in particular for porous media. In this work, we analyse FIB‐SEM data from ethyl cellulose porous films made from ethyl cellulose and hydroxypropyl cellulose (EC/HPC) polymer blends. These films are used as coatings for controlled drug release. The aim is to perform image segmentation, i.e. to identify which parts of the image data constitute the pores and the solid, respectively. Manual segmentation, i.e. when a trained operator manually identifies areas constituting pores and solid, is too time‐consuming to do in full for our very large data sets. However, by performing manual segmentation on a set of small, random regions of the data, we can train a machine learning algorithm to perform automatic segmentation on the entire data sets. The method yields good agreement with the manual segmentations and yields porosities of the entire data sets in very good agreement with expected values. The method facilitates understanding and quantitative characterization of the geometrical structure of the materials, and ultimately understanding of how to tailor the drug release. [ABSTRACT FROM AUTHOR]

Correlations between microstructure and Q-factor of tunable solidly mounted Ba0.25Sr0.75TiO3 (BSTO) thin film bulk acoustic wave resonators are studied using analysis of test structures prepared at different growth temperatures of the BSTO films varying in the range 450-650 °C. The observed changes in the Q-factor with growth temperature are correlated with related changes in microstructure, including the grain size, texture misalignment, interfacial amorphous layer, surface roughness, and deterioration of the Bragg reflector layers. The correlations are established through analysis of corresponding extrinsic acoustic loss mechanisms, including Rayleigh scattering at localized defects, acoustic attenuation by amorphous layer, generation of the shear waves leaking into the substrate, waves scattering by surface roughness, and resonance broadening by local thickness variations. It is shown that the waves scattering by surface roughness at the BSTO film interfaces is the main loss mechanism limiting the Q-factor of the BSTO thin film bulk acoustic wave resonators. [ABSTRACT FROM AUTHOR]

Deals with a study which investigated the development of interfacial microstructure during cooling of a zinc oxide varistor material from the sintering temperature through a combination of analytical electron microscopy and x-ray diffractometry. Information on zinc oxide varistor materials; Methodology of the study; Results and discussion.

Abstract: Tool degradation may be significantly different depending on small variations in chemical compositions of the workpiece material. The present study is an in-depth microstructure investigation of worn low content polycrystalline cubic boron nitride tool materials after dry hard turning of steels with low and high sulphur contents. The results illustrate the important role of sulphur content on the degradation of the crater zone. Sulphides tend to adhere on the wear surface and form layers that protect the tool from workpiece ingress. In the absence of sulphides in the workpiece material, no protective layer can form and iron compounds make their way into the tool microstructure already at lower cutting speeds (150m/min) and preferably attack cBN grains compared to Ti(C,N) grains. [Copyright &y& Elsevier]

Examines the microstructure of YBa[sub 2]Cu[sub 3]O[sub 7-delta] (YBCO) grain boundaries obtained at step edges on LaAlO[sub 3] substrates by scanning and transmission electron microscopy. Morphology of the YBCO grain boundary; Orientation of films on the substrate surface; Difference between upper and lower boundary geometry.

Abstract: Titanium carbide (TiC) coatings for tribological applications were deposited on high speed steel. Several coatings with different titanium to carbon ratio were deposited by means of physical vapour deposition in which titanium was evaporated and carbon was sputtered. The coatings were characterised using analytical electron microscopy. It was observed that the change in titanium to carbon ratio significantly changed the microstructure of the coatings. The low carbon containing coatings consisted of columnar grains exhibiting a preferred crystallographic orientation whereas the coating with highest carbon content consisted of randomly ordered TiC grains in an amorphous carbon matrix. Energy filtered transmission electron microscopy revealed a change in Ti/C ratio as the distance from the substrate increased. The titanium to carbon ratio was observed to increase with distance from the substrate until a stable level was reached. This is due to a variation in the titanium evaporation during the early stages of film growth. This change of the titanium to carbon ratio affected the columnar growth in the initial stage of coating growth for the coatings with low carbon content. [Copyright &y& Elsevier]

Abstract: The microstructure of a commercial polycrystalline cubic boron nitride (PCBN) tool material was studied using scanning electron microscopy with energy-dispersive X-ray analysis and transmission electron microscopy with electron energy loss spectroscopy and energy filtered TEM. These results were compared with results from X-ray diffraction and thermodynamic calculations. It is shown that this PCBN material consists of cBN both as micrometre-sized and nanometre-sized grains. The micrometre-sized grains show primarily straight phase boundaries and little reaction with the surrounding matrix. The matrix consists of mainly TiCN, with grains ranging from nanometres to sub-micrometres. The C and N content in TiCN varies, indicating a system far from equilibrium. Only small reaction zones are found and the major reaction is the one between Al and O, forming Al2O3. It is also shown that it is possible to prepare samples thin enough for TEM/EFTEM/EELS studies, enabling the study of minor reaction phases like TiB2. [Copyright &y& Elsevier]

TiB2 coatings were deposited onto cemented carbide substrates by d.c. magnetron sputtering using different substrate bias voltage, both positive and negative. Transmission electron microscopy, TEM, was used to investigate how the microstructure relates to deposition parameters. All coatings investigated were found to be crystalline with dense grain and grain boundaries, i.e. no pores or voids were detected. It was concluded that the (0001) planes were preferentially oriented perpendicular to the growth direction for all coatings, independent of substrate bias voltage. However, the orientation of the grains was more random during the initial nucleation. The main mechanism for development of this (0001) texture of d.c. magnetron sputtered TiB2 coatings is proposed to be due to a rapid growth in the [0001] direction. There is a change in coating morphology as the substrate bias changes from negative (-110 V) to positive (+50 V). The negatively biased coatings have a columnar structure with a grain size that increases with coating thickness, while coatings grown with positive bias have a dense fibrous morphology, with smaller and more uniform grain size. [Copyright &y& Elsevier]

Abstract: Sr3Ru2O7/Sr2RuO4 eutectic system is investigated by electron backscattering diffraction (EBSD) and X-ray diffraction (XRD). The eutectic growth enables the solidification of the two phases in an ordered lamellar pattern extending along the growth direction, namely the b-axis direction. The eutectic material thus provides in the a–c plane two distinct interfaces having different microstructures with respect to the growth direction. Our analysis shows that, across the inplane c-axis direction (characterized by a poor lattice matching), the b-axis orientation is not constant at the individual interfaces, showing an orientation spread of about 5°. However, across the in-plane a-axis direction (characterized by a good lattice matching), the b-axis orientation does not change within a few tenths of degree (about 0.25°). Such information at nanoscale is also verified on a macroscopic level by standard XRD investigation. [Copyright &y& Elsevier]

Abstract: The local effect of wear on the microstructure of a commercial low content Polycrystalline Cubic Boron Nitride (PCBN) tool material, with ∼55vol% cBN in a Ti(C,N)-matrix, has been investigated. The PCBN tool was used in dry hard turning of a case hardened steel. A crater developed on the rake face of the tool edge and the microstructure of this area has been studied in detail using Scanning Electron Microscopy (SEM) with Energy-Dispersive X-ray analysis and Transmission Electron Microscopy (TEM) with Electron Energy-Loss Spectroscopy and Energy Filtered TEM. A lift-out technique in a Focused Ion Beam/SEM instrument was used to produce thin foil specimens, <80nm in thickness. This technique provided the possibility to produce specimens from a specific location with sub-micron resolution. In this case, specimens were taken from across the rake face of the worn PCBN tool. The spatial resolution was substantially improved by using thin foils and it was possible to investigate the degraded microstructure down to the nanometre scale. The results show an adherent layer smearing the crater on the rake face of the PCBN tool cutting edge. Closer investigation of this layer reveals an inner layered structure with some characteristic features. This layer consists of elements from the workpiece material. The tool–adherent layer interface is smooth, showing rounded, concave wear surfaces of micron-sized cBN instead of the original flat grain surfaces. Larger Fe-rich areas are found which are oxidised on the surface, sometimes containing smaller amounts of Cr and Ni. Mn and S are found as larger, often elongated areas primarily close to the tool–adherent layer interface. The dominating degrading mechanism appears to be chemical degradation. The detailed microstructure of the tool–adherent layer interface and the adherent layer is presented. [Copyright &y& Elsevier]

Abstract: The microstructure of silver-containing indium tin oxide (ITO) films, deposited by sequential reactive direct current (DC) magnetron sputtering of ITO and Ag, was investigated by transmission electron microscopy (TEM) with selected area electron diffraction, high resolution TEM, energy dispersive spectroscopy, and energy-filtering TEM (EFTEM). All films had a columnar structure with (222) texture. The silver additive did not alter the ITO grain orientation, even though the columnar size of the ITO grains was decreased slightly when the silver content was increased. Nanoparticles of silver, with sizes ranging from 2 to 5 nm, were distributed in layers, as demonstrated by EFTEM using the Ag M4,5 peak. The influence of the silver deposit on the microstructure and properties of the ITO films is discussed. [Copyright &y& Elsevier]