Cross-sectional TEM Specimens Research Articles

Investigation of instability of M23C6 particles in F82H steel under electron and ion irradiation conditions

In order to clarify the instability of M23C6 in F82H steel under irradiation, both electron irradiation using a high voltage electron microscope (HVEM) and ion irradiation using an ion accelerator were performed. For the electron irradiation, in-situ observation under 2 MV electron irradiation and ex-situ high resolution electron microscopic (HREM) analysis were utilized to evaluate the response of M23C6 against irradiation. The temperature dependence of the irradiation induced instability of the carbide was first confirmed: 293 K < T < 573 K, by observation of lowering in contrast at the periphery of carbides, 698 K < T < 773 K, fragmentation at the interface between carbides and matrix, and at 773 K, formation and coarsening of new particles near the periphery of M23C6. HREM analysis showed the loss of the lattice fringe contrast at the pre-existing M23C6 precipitates at temperatures ranging from 473 to 773 K, indicating severe loss of crystallinity due to dissolution of the constituent atoms though irradiation-enhanced diffusion under the vacancy diffusion by the focused electron beam irradiation. For the ion irradiation, 10.5 MeV-Fe3+ ion was applied to bombard the F82H steel at 673 K to achieve the displacement damage of ≈20 dpa at the depth of 1.0 μm from surface. Cross-section TEM specimens were prepared by a focused ion beam technique. The shrinkage of carbide particles was observed especially near the irradiation surface. Besides, the lattice fringes at the periphery of carbide were observed in the irradiated M23C6 by the HREM analysis, which is different from that observed in the electron irradiation. It was clarified that the instability of M23C6 is dependent on the irradiation conditions, indicating that the flow rate of vacancy type defects might be the key factor to cause the dissolution of constituent atoms of carbide particles into matrix under irradiation.

Characterisation of the wear mechanisms in retrieved alumina-on-alumina total hip replacements

Due to their superior wear performance and biocompatibility compared to alternative polymer/metal prostheses, alumina-on-alumina total hip replacements (THRs) are extensively used for young and more active patients. However, the understanding of the wear mechanisms of alumina in vivo remains relatively poor, and there remains little quantitative understanding of the structural and chemical changes at the articulating surface. In the current study, the surface and sub-surface microstructures of retrieved in vivo alumina THRs are presented. Severe wear, also called stripe wear, was observed in all cases. The transition between the stripe wear and the mild wear was very sharp. Site-specific cross-section TEM specimens were prepared by Focused Ion Beam (FIB) at the stripe boundary region. The results suggest predominantly intergranular fracture occurred that was restricted to the outer layer of grains below the surface, with transgranular fracture also occurring in the stripe wear region. Cracking was believed to be initiated by extensive dislocation slip. A thin layer of hydroxide was also observed at the extreme surface of the mild wear region by aberration-corrected high resolution transmission electron microscopy (HRTEM). The wear mechanisms are discussed.

TEM identification of subsurface phases in ternary U–Pu–Zr fuel

Phases and microstructure in as-cast, annealed at 850 °C, and subsequently cooled U–23Pu–9Zr fuel were characterized using scanning and transmission electron microscopy techniques. SEM examination shows formation of three phases in the alloy that were identified in TEM using selective area diffraction pattern analysis: α-Zr globular and elongated δ-UZr2 inclusions and a thick oxide layer formed on top of β-Pu phase, which has been initially assumed to be ζ-(U, Pu). However, further examination of the cross-sectional TEM specimens identified the matrix phases as δ-UZr2, β-Pu, and (U, Zr)ht. Two types of inclusions were observed in the immediate vicinity of the specimen surface and they were consistent with α-Zr and ζ-(U, Pu).

Three-dimensional characterization of BaHfO3 precipitates in GdBa2Cu3O7-y flim using STEM tomography.

IntroductionSince the discovery of REBa2Cu3O7-y (RE: Rare Earth element, REBCO) superconductors, they have been expected as the best candidates for the power cable application due to its high critical temperature (Tc) and critical current density (Jc). Among those REBCO superconductors, GdBa2Cu3O7-y (GdBCO) have been receiving great interest because they have higher Tc and Jc than YBa2Cu3O7-y [1].GdBCO with various types of precipitates as artificial pinning centers (APCs) have been proposed to minimize the anisotropy of Jc characteristics under the magnetic field. Among those precipitates, BaHfO3 (BHO) was found most effective precipitates as APCs in GdBCO film prepared by pulsed laser deposition (PLD) method [2]. It is therefore necessary to investigate not only the morphologies but also the dispersion of BHO precipitates within the GdBCO, to understand the role of BHO for the superconducting characteristics. In this study, morphologies and dispersions of BHO precipitates were characterized three-dimensional by scanning transmission electron tomography ExperimentalBHO dispersed GdBCO films were fabricated on Hastelloy C-276TM substrates with buffer layers of CeO2/LaMnO3/MgO/ Gd2ZrO7 by PLD method.To observe microstructure of GdBCO film with BHO precipitates, cross-section TEM specimens were prepared by FIB method using Quanta 3D-200 (FEI, USA) with acceleration voltage from 2 to 30 kV. Three-dimensional information such as morphology and dispersion, of BHO precipitates were characterized by electron tomography using STEM-HAADF. Result and discussionFigure1 shows three-dimensional reconstructed volume of BHO precipitates in GdBCO, which revealed that fine BHO precipitates have rod- and plate-like morphologies with homogeneous dispersion in GdBCO. In addition, growth directions of these precipitates were found with wide angular distributions from growth direction of GdBCO. Anisotropy of Jc in the magnetic fields was probably enhanced by various growth directions and homogeneous dispersion of nanosized BHO within GdBCO.jmicro;63/suppl_1/i26/DFU080F1F1DFU080F1Fig. 1.Three-dimensional reconstructed volume of BHO.

Focus Ion Beam for Cross-Sectional TEM Specimen Preparation of Nanomaterials

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Large Thin Area Preparation of Cross-Sectional TEM Specimens of III-V Semiconductors

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Subsurface sliding wear damage characterization in Al–Si alloys using focused ion beam and cross-sectional TEM techniques

Abstract This paper illustrates the distinctive capabilities of using focused ion beam (FIB) techniques to elucidate the microstructure that forms beneath the worn regions of samples subjected to laboratory tests under ultra-mild wear (UMW) conditions and those extracted from specific regions of a worn surface of engine blocks. TEM investigations of cross-sectional samples excised with a focused gallium-ion beam to obtain electron transparency of the first few micrometers of the contact surface were effective in providing novel information on the micromechanisms of UMW that are not readily obtained with conventional microscopy. Two FIB sample preparation techniques, namely the lift-out and H-bar techniques were used to prepare site-specific cross-sectional TEM specimens from Al–11% Si alloys subjected to pin-on-disk and dynamometer tests. In both cases, the aluminum matrix was heavily deformed in the top few micrometers below the contact surface, which resulted in the formation of ultrafine grains. Damage to the silicon particles was also observed. Additionally, a tribolayer (or an oil-residue layer) whose thickness increased with sliding cycles, was developed on the contact surfaces. It was concluded that the development of the oil residue layer supported by a layer of ultrafine grain structure was necessary to maintain the low wear rates.

Nanoscale sculpting of ferromagnetic structures by electron beam ablation

We report an electron beam (e-beam) fabrication method to produce sub-5 nm structures, e.g. nanohole-arrays, nanojunctions and nanotips inside a TEM. The method is demonstrated using ferromagnetic nickel cross-sectional TEM specimens as well as electrochemically etched nickel tips. Different e-beam shapes and electron guns are compared, including point versus line focus and field-emission versus LaB6 guns. As an extension of this 2-D patterning of nanostructures, a 3-D nanofabrication technique has been introduced using a high tilt tomographic holder. An electrochemically etched nickel tip of initially 18 nm in radius is sculpted down to sub-5 nm diameter. In some cases, mostly in 3-D nanofabrication, a protrusion during hole drilling was observed and confirmed by EELS as pure nickel.

Nanostructured reactive metallic multilayers

Metallic multilayers have been used in cross-sectional TEM specimen geometry to explore nanostructuring routes using ion and electron beams (top-down) as well as self-organised nanopatterning (bottom-up). Intermetallic alloy formation during heat treatment is studied for binary and ternary layer compositions. A choice of pillars (0D), 1D and 2D layer geometries are used to explore dimensionality effects.

Improving the High-Temperature Tensile Strength of SiTiC/TiAl Micro Composites by Interface Engineering

AbstractSiC-fiber-reinforced TiAl composites (SiC/TiAl) have attractive attention due to their potential for replacing titanium and nickel-base alloys in aerospace systems such as advanced turbine engines and hypersonic vehicles where specific strength and stiffness at high temperature are critical. The interface layers of SiC/TiAl are believed to contribute strongly to its mechanical properties. A variety of interface modification, such as C, BN, W, and/or Mo coatings has been applied to the fiber to produce composites, together with the identification of several new interface modification systems, showing promise for high-performance fibers and improved composite properties. A research from a perfect cross-sectional view to get more direct and reliable interfacial information especially about bonding around the fiber circumference, has been limited partly due to the difficulty of preparing suitably thin TEM specimen without damaging the interface layers. We report our preparation method for a perfect cross-sectional TEM specimen of SiC/TiAl and the interface characterization results.Single SiC-based Si-Ti-C-O fiber (SiTiC) ˜13 μm in diameter containing about 2% Ti to improve its thermal stability has been used as a reinforcement. Chemical or physical vapor deposition has been used to deposit C or TiAl layer. C layer has been deposited-uniformly around the fiber at a thickness of about 100 nm and TiAl coating at about 1400 nm. C layer consisted of large amounts of micro crystals of about 1-30 nm accumulated around the interface of C layer and fiber. TiAl layer consisted of crystals of about 60-360nm.The specimen has been annealed at 1173 K for 2 hrs in Ar, and prepared by sandwiching and 3mm disks obtained by ultrasonic drilling and mechanical-polishing to ∼100 μm. Those disks have been further ground by a dimpler to ∼10 μm, and argon-ion-milling to get an electron-beam-transparent foil. H-9000UHR II TEM operating at 300 kV, equipped with EDX (prove 1nm) has been used.Interfacial reaction and diffusion mainly occurred in the interface between the C layer and SiTiC fiber and the C and TiAl layers. No direct reaction or diffusion occurred between the SiTiC fiber and TiAl layer. Small amounts of needle-like compound assigned as Aluminum Titanium Carbide, (Ti3AlC)5C, propagating into the fiber has been found at the interface area. These compounds consist of C, Si, O, Ti, and Al, indicating they are reaction and diffusion products of SiTiC fiber and TiAl. Such Aluminum Titanium Carbide propagating into the fiber seems to induce new stress concentration and generate new crack in the fiber and degrade the fiber and the composite strength. Combined with the tensile testing of SiTiC/TiAl single fiber reinforced composites reported previously, we surmise that the large amounts of small crystals accumulating in the C layer contribute to resistance to interfacial reaction and diffusion between the fiber and TiAl layer.

Determination of strain within Si1-yCy layers grown by CVD on a Si Substrate

AbstractIn this work, we performed quantitative measurements of strain in structures consisting of a 30 nm-thick Si1-yCy layer grown by chemical vapour deposition (CVD) on a Si (001) substrate at 550 or 600°C. The total C concentration varies from 0.67 to 1.97% that was measured by SIMS. Geometric phase analysis (GPA) of high resolution transmission electron microscopy (HR TEM) cross-section images and convergent beam electron diffraction (CBED) were used to deduce the strain within these Si1-yCy layers. Finite-element simulations were carried out to estimate the impact of strain relaxation in thin areas of a specimen. These results were compared with the data obtained by high resolution X-ray diffraction and Raman spectroscopy and with the predictions of elasticity theory. Particular interest is paid to the formation of the structural defects within Si1-yCy layers as a function of a C concentration, growth temperature and incorporated strain. Both cross-sectional and plan-view TEM specimen configurations were used to obtain quantitative information on the defect size distribution, their density and structure.

Cross-sectional TEM Sample Preparation for Nanowires or Porous Films Grown on a Substrate

Abstract Nanowires or porous films grown on a substrate normally lack mechanical strength, and may be subject to damage during specimen preparation. When we made cross-sectional TEM specimen for this type of sample, we modified the traditional method by covering the sample with epoxy to improve the film strength, and applying single-section ion milling to protect the film from over-milling. The sample surface is first covered with G1 epoxy. We choose G1 for this application because it is relatively thick and cures at low temperature. For samples with a dense-growth of nanowires or a thick porous film, a brief moment in vacuum helps to get rid of the air bubbles in the epoxy. The glue is cured at 100 degree C for 10 minutes, until its color turns to a reddish brown. To remove the excess glue and flatten the surface, the sample is then ground and polished until the glue is less than 0.1 mm thick.

The effect of 180 °C-annealing on the electrochemical behavior of nano-thick zinc-electroplated copper in aqueous solutions with different pH

The anodic polarization and a.c. impedance measurements of 4 nm- and 25 nm-zinc-electroplated copper specimens were conducted in aqueous solutions with four different pH-values. The nano-thick zinc-electroplated copper was tested after electroplating and annealing at 180 °C for 1, 2 and 3 h, respectively. The results showed that the open-circuit potential (OCP) of 25 nm-zinc electroplated copper shifted toward noble potential after annealing. A more noble OCP of 25 nm zinc-electroplated copper could be achieved when zinc plated copper was annealed at 180 °C up to 1 h. Similar change was found for 4 nm-zinc electroplated copper only in neutral and alkaline solutions. The a.c. impedance response of all nano-thick zinc-electroplated copper corresponded to two Randle’s circuits in series, in which the circuit measured in a high frequency region of their Nyquist diagrams revealed the electrochemical behavior of nano-thick zinc deposits. The charge transfer resistance of the nano-thick zinc electroplated copper was significantly raised after annealing at 180 °C when tested in pH 9.5 solution. Microstructures of the aforementioned nano-thick zinc electroplated copper were examined with cross-sectional TEM specimens. A distinct phase interface between zinc and copper was observed for as plated specimens, while alloying of zinc and copper at the interface was detected after annealing at 180 °C for 1 h. Electroplated zinc diffused into the copper foil during the 180 °C-annealing and the corrosion potential of the anodic polarization curve indicated the condition of the alloy surface. The annealing effect of 4 nm- and 25 nm-zinc electroplated copper specimens could be related to the results of electrochemical measurement.

Preparation of GaN-based cross-sectional TEM specimens by laser lift-off

Laser lift-off (LLO) technology is successfully used to prepare GaN-based TEM cross-sectional specimens. Detailed procedures of the method to prepare the specimens are demonstrated. Large thin areas suitable for TEM analysis were obtained. TEM images of the resulting GaN interface are studied, and the changes in structural quality are confined to approximately the first 250 nm of the epilayer. Clear TEM images of the whole epilayer and the InGaN quantum wells and the HRTEM images of the superlattice layer are demonstrated, showing that LLO is a quick and ideal method to study the crystal structure of the epilayer, especially if only the upper layers are of interest.

Optimized preparation of cross-sectional TEM specimens of organic thin films

We present a route for the preparation of cross-sectional TEM specimens of crystalline organic thin films which minimizes the mechanical, chemical and thermal load of the organic film during preparation and allows to take TEM images with molecular resolution. A typical example of a thin film of diindenoperylene capped with a thin layer of gold is shown to demonstrate the application of the technique for the investigation of metal–organic interfaces.

Preparation of Cross-sectional Tem Specimens of Obliquely Deposited Magnetic thin Films on a Flexible Tape; Electron Transparency Beyond 6 Micron !

Journal Article Preparation of Cross-sectional Tem Specimens of Obliquely Deposited Magnetic thin Films on a Flexible Tape; Electron Transparency Beyond 6 Micron ! Get access Enrico G Keim, Enrico G Keim MESA+ Research Institute, Central Materials Analysis Laboratory, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands Search for other works by this author on: Oxford Academic Google Scholar LT Nguyen, LT Nguyen MESA, + Research Institute, Systems and Materials for Information storage (SMI), University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands Search for other works by this author on: Oxford Academic Google Scholar J Cock Lodder J Cock Lodder MESA, + Research Institute, Systems and Materials for Information storage (SMI), University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 8, Issue S02, 1 August 2002, Pages 1346–1347, https://doi.org/10.1017/S1431927602103357 Published: 01 August 2002

Querschnittpräparation von Spänen aus Ti6Al4V für die Analyse im Transmissionselektronenmikroskop - Verfahren und erste Ergebnisse / Cross-Sectional TEM Sample Preparation for the Analysis of Chips of Ti6Al4V - Preparation Method and a Few Results

In order to improve the machinability of Titanium alloys a better understanding of the chip formation process is needed. Microstructural analysis of chips produced at high cutting speeds could lead to a first estimation of temperature and the degree of deformation, if structural changes can be observed. Such analysis can be performed by means of TEM only, but microstructural observations on the cross-section of the chip is essential for this. Therefore a method for preparation of cross-sectional TEM specimen from Ti6Al4V chips has been developed. The preparation steps are presented in detail and some micrographs from these specimen are given in this work.

Three Dimensional Characterization of a Specific Site by an FIB Micro-Sampling Technique

We have developed an FIB micro-sampling technique to prepare both plan view and cross-sectional TEM specimens from a specific site.The instruments that were used in this study are the Hitachi FB-2000A FIB system equipped a with micromanipulator unit and an HF-2200 cold field emission 200kV analytical TEM equipped with a scanning attachment allowing both STEM and SEM imaging.Figure 1 shows a procedure to prepare a micro-sample for either plan view or cross-sectional TEM observation of the specific site. First, the micro-sample for plan view TEM observation is trench milled by using an FIB(Figure 1a). Second, a tip of a micromanipulator W-probe is bonded to the micro-sample with the FIB assisted metal deposition. Then, the micro-sample is lifted out and transferred onto a micro-sample carrier(Figure 1b).

FIB Dimpling: A Method for Preparing Plan-View TEM Specimens

Abstract Failure analysis in the microelectronic industry via TEM has long dealt with the specimen preparation spatial resolution problem—the ability to prepare useful TEM specimens at very small pre-selected locations. This problem is made more difficult with time because, while device structures become smaller and more dense, the failure rate of individual devices is extremely low and dropping. TEM analysts, therefore, must prepare specimens that optimally present a single faulty component within an ocean of a billion or more similar components. Sophisticated electrical testers can find the faulty component and transfer its coordinates to a FIB tool where the failure can be marked. Cross section TEM specimens are appropriate when it is suspected that the failure is caused by a defect in the stack of metal and insulators constructed on the top of the device substrate (usually silicon). Plan view TEM specimens are appropriate when the electrical signature of the failure indicates that the fault lies in the Si itself-dislocations or some other crystal defect.

Determination of polarity of GaN cross-section TEM specimens using quantitative electron diffraction

It is shown that electron diffraction patterns taken from small areas (typically 4–20 nm) of GaN cross-section TEM specimens allow unequivocal determination of the local polarity. As experimental data we used a set of diffraction patterns from an area with the same polarity but with an increasing thickness due to the wedge-shaped morphology of the TEM specimen. The polarity is determined using a least-squares refinement procedure in which the local misorientation and specimen thickness is refined for the two possible polarities. The refinements show that one polarity has much better agreement between calculated and experimental intensities of the reflections for all diffraction patterns of the set, allowing straightforward identification of polarity.