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Type Prosa, T.J.; Strennen, S.; Olson, D.; Lawrence, D.; Larson, D.J.
  Publication A Study of Parameters Affecting Atom Probe Tomography Specimen Survivability Volume Journal Article
Pages 2019
  Abstract  
  Corporate Author Microscopy and Microanalysis  
Publisher 25  
Editor 2
  Summary Language 425-437 Series Editor analysis yield; experimental design; electric field; tensile stress; silicon-based materials  
Abbreviated Series Title Specimen survivability is a primary concern to those who utilize atom probe tomography (APT) for materials analysis. The state-of-the-art in understanding survivability might best be described as common-sense application of basic physics principles to describe failure mechanisms. For example, APT samples are placed under near-failure mechanical-stress conditions, so reduction in the force required to initiate field evaporation must provide for higher survivability--a common sense explanation of survivability. However, the interplay of various analytical conditions (or instrumentation) and how they influence survivability (e.g., decreasing the applied evaporation field improves survivability), and which factors have more impact than others has not been studied. In this paper, we report on the systematic analysis of a material composed of a silicon-dioxide layer surrounded on two sides by silicon. In total, 261 specimens were fabricated and analyzed under a variety of conditions to correlate statistically significant survivability trends with analysis conditions and other specimen characteristics. The primary result suggests that, while applied field/force plays an obvious role in survivability for this material, the applied field alone does not predict survivability trends for silicon/silicon-dioxide interfaces. The rate at which ions are extracted from the specimen (both in terms of ions-per-pulse and pulse-frequency) has similar importance.
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2018/11/05 1431-9276 no NU @ karnesky @ 11541
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Dong, Y.; Etienne, A.; Frolov, A.; Fedotova, S.; Fujii, K.; Fukuya, K.; Hatzoglou, C.; Kuleshova, E.; Lindgren, K.; London, A.; Lopez, A.; Lozano-Perez, S.; Miyahara, Y.; Nagai, Y.; Nishida, K.; Radiguet, B.; Schreiber, D.K.; Soneda, N.; Thuvander, M.; Toyama, T.; Wang, J.; Sefta, F.; Chou, P.; Marquis, E.A. Atom Probe Tomography Interlaboratory Study on Clustering Analysis in Experimental Data Using the Maximum Separation Distance Approach Journal Article 2019 Microscopy and Microanalysis 25 2 356-366 atom probe tomography; cluster analysis; maximum separation We summarize the findings from an interlaboratory study conducted between ten international research groups and investigate the use of the commonly used maximum separation distance and local concentration thresholding methods for solute clustering quantification. The study objectives are: to bring clarity to the range of applicability of the methods; identify existing and/or needed modifications; and interpretation of past published data. Participants collected experimental data from a proton-irradiated 304 stainless steel and analyzed Cu-rich and Ni-Si rich clusters. The datasets were also analyzed by one researcher to clarify variability originating from different operators. The Cu distribution fulfills the ideal requirements of the maximum separation method (MSM), namely a dilute matrix Cu concentration and concentrated Cu clusters. This enabled a relatively tight distribution of the cluster number density among the participants. By contrast, the group analysis of the Ni-Si rich clusters by the MSM was complicated by a high Ni matrix concentration and by the presence of Si-decorated dislocations, leading to larger variability among researchers. While local concentration filtering could, in principle, tighten the results, the cluster identification step inevitably maintained a high scatter. Recommendations regarding reporting, selection of analysis method, and expected variability when interpreting published data are discussed. Cambridge University Press 2019/02/04 1431-9276 no NU @ karnesky @ 11537
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Zhang, Guo Fan; Sauvage, Xavier; Wang, Jing Tao; Gao, Nong; Langdon, Terence G. Decomposition of Nanostructured Martensite in Cu-Al Alloys Processed by High-Pressure Torsion Journal Article 2010 Materials Science Forum 667-669 469-474 The phase decomposition was investigated in Cu-Al alloys processed to a nanostructure condition by High Pressure Torsion (HPT). The microstructures are characterized by optical microscopy (OM), X-ray diffraction (XRD) and Atom Probe Tomography (APT). The results show that the → (1 + decomposition reaction begins in the early stage of annealing and it is much faster than in the coarse-grained state although there are similar phases after annealing. 1662-9752 no NU @ karnesky @ zhang_decomposition_2010 11324
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Zhang, Tong-Yi; Ren, Hang Solute concentrations and strains in nanograined materials Journal Article 2013 Acta Materialia 61 2 477-493 Nanograined materials; Grain boundary segregation; Stresses; Solute concentrations; Coupling between stress and concentration Taking advantage of both the Gibbs and McLean adsorption isotherms, we develop a Gibbs-approach-based adsorption isotherm for grain boundary (GB) segregation in nanograined (ng) polycrystals. An excess GB thickness is introduced to describe the excess of GB atomic volume in comparison with the atomic volume in lattice. The GB bulk modulus is determined with the excess GB thickness and a universal function. The newly developed adsorption isotherm is able to analyze simultaneously stresses, concentrations and their coupling behaviors in grains and GBs. Numerical calculations and plots are conducted to illustrate the theoretical analysis. The results show that the apparent solute concentration could be greatly enhanced in ng materials, due to a large grain boundary volume fraction and a considerable increase in the lattice concentration that is, in turn, boosted by the concentration-induced stresses. 1359-6454 no NU @ karnesky @ 11418
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Caballero, F.G.; Yen, Hung-Wei; Miller, M.K.; Yang, Jer-Ren; Cornide, J.; Garcia-Mateo, C. Complementary use of transmission electron microscopy and atom probe tomography for the examination of plastic accommodation in nanocrystalline bainitic steels Journal Article 2011 Acta Materialia In Press Corrected Proof Bainite; Steels; Three-dimensional atom probe; Transmission electron microscopy A displacive transformation involves the motion of a glissile interface. As in work hardening, its motion can be halted by defects such as dislocations, stacking faults or twins in the austenite. The defects are created when the shape deformation accompanying bainite growth is accommodated by plastic relaxation of the surrounding austenite. The growing plate stops when it collides with the austenite grain boundary. Because transformation from strong austenite leads to fine plates, alloys can be designed such that the bainite transformation is suppressed to low temperatures (125350 °C), leading to a nanoscale bainitic microstructure. Complementary high-resolution transmission electron microscopy and atom probe tomography have provided new experimental evidence on the accommodation of transformation strain, a subject critically relevant to understanding the atomic mechanisms controlling bainitic ferrite growth. 1359-6454 <p><br/>A displacive transformation involves the motion of a glissile interface. As in work hardening, its motion can be halted by defects such as dislocations, stacking faults or twins in the austenite. The defects are created when the shape deformation accompanying bainite growth is accommodated by plastic relaxation of the surrounding austenite. The growing plate stops when it collides with the austenite grain boundary. Because transformation from strong austenite leads to fine plates, alloys can be designed such that the bainite transformation is suppressed to low temperatures (125-350��C), leading to a nanoscale bainitic microstructure. Complementary high-resolution transmission electron microscopy and atom probe tomography have provided new experimental evidence on the accommodation of transformation strain, a subject critically relevant to understanding the atomic mechanisms controlling bainitic ferrite growth.</p> no NU @ karnesky @ 5 11143
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Wang, Ren-Nian; Tang, Bi-Yu; Peng, Li-Ming; Ding, Wen-Jing Ab initio study of the effect of Zr content on elastic and electronic properties of L12-Al3(Sc1-xZrx) alloys Journal Article 2012 Computational Materials Science 59 87-93 Special quasi-random structure; Stability; Elastic properties; Electronic structures; Ab initio calculation First-principles calculations were performed to investigate the structural, elastic and electronic properties of L12-Al3(Sc1-xZrx) (x = 0.25, 0.5 and 0.75) based on special quasi-random structures (SQSs) with 32 atoms. As the content of Zr atoms increased, the lattice parameters of L12-Al3(Sc1-xZrx) were increased whereas thermodynamical stability was lowered. The obtained C11 and C44 were reduced slightly, indicating that the incompressibility along the principle axes and the resistance to shear in 0 0 1 direction on the {1 0 0} plane were lowered, the shear and Young's modulus were also reduced while the bulk modulus were slightly larger. The ductility was improved due to increase of the B/G ratio and Cauchy pressure. The electronic structures revealed that the dominant hybridization between the Al p states and transition-metal d states became weaker with increasing of the content of Zr. 0927-0256 no NU @ karnesky @ 11367
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Buchenauer, D.A.; Karnesky, R.A.; Fang, Z.Z.; Ren, C.; Oya, Y.; Otsuka, T.; Yamauchi, Y.; Whaley, J.A. Gas-driven permeation of deuterium through tungsten and tungsten alloys Journal Article 2016 Fusion Engineering and Design 109-111 Part A 104-108 Iter; permeation; Plasma facing component; Tungsten; Tungsten alloy To address the transport and trapping of hydrogen isotopes, several permeation experiments are being pursued at both Sandia National Laboratories (deuterium gas-driven permeation) and Idaho National Laboratories (tritium gas- and plasma-driven tritium permeation). These experiments are in part a collaboration between the US and Japan to study the performance of tungsten at divertor relevant temperatures (PHENIX). Here we report on the development of a high temperature (<=1150 °C) gas-driven permeation cell and initial measurements of deuterium permeation in several types of tungsten: high purity tungsten foil, ITER-grade tungsten (grains oriented through the membrane), and dispersoid-strengthened ultra-fine grain (UFG) tungsten being developed in the US. Experiments were performed at 500-1000 °C and 0.1-1.0 atm D2 pressure. Permeation through ITER-grade tungsten was similar to earlier W experiments by Frauenfelder (1968-69) and Zaharakov (1973). Data from the UFG alloy indicates marginally higher permeability (< 10×) at lower temperatures, but the permeability converges to that of the ITER tungsten at 1000 °C. The permeation cell uses only ceramic and graphite materials in the hot zone to reduce the possibility for oxidation of the sample membrane. Sealing pressure is applied externally, thereby allowing for elevation of the temperature for brittle membranes above the ductile-to-brittle transition temperature. 0920-3796 no NU @ karnesky @ 11514
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Sha, Gang; Yao, Lan; Liao, Xiaozhou; Ringer, Simon P.; Chao Duan, Zhi; Langdon, Terence G. Segregation of solute elements at grain boundaries in an ultrafine grained Al-Zn-Mg-Cu alloy Journal Article 2011 Ultramicroscopy Special Issue: 52nd International Field Emission Symposium 111 6 500-505 Aluminium alloy; Atom probe tomography; Equal-channel angular pressing; Grain boundaries; Solute segregation The solute segregation at grain boundaries (GBs) of an ultrafine grained (UFG) Al-Zn-Mg-Cu alloy processed by equal-channel angular pressing (ECAP) at 200 °C was characterised using three-dimensional atom probe. Mg and Cu segregate strongly to the grain boundaries. In contrast, Zn does not always show clear segregation and may even show depletion near the grain boundaries. Trace element Si selectively segregates at some GBs. An increase in the number of ECAP passes leads to a decrease in the grain size but an increase in solute segregation at the boundaries. The significant segregation of alloying elements at the boundaries of ultrafine-grained alloys implies that less solutes will be available in the matrix for precipitation with a decrease in the average grain size. 0304-3991 no NU @ karnesky @ 11213
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Martinez, E.; Ronsheim, P.; Barnes, J.-P.; Rochat, N.; Py, M.; Hatzistergos, M.; Renault, O.; Silly, M.; Sirotti, F.; Bertin, F.; Gambacorti, N. Lanthanum diffusion in the TiN/LaOx/HfSiO/SiO2/Si stack Journal Article 2011 Microelectronic Engineering Proceedings of the 17th Biennial International Insulating Films on Semiconductor Conference, 17th Bi 88 7 1349-1352 Metal/high-k stack; TiN; HfSiO; La; Interfacial dipole; Threshold voltage tuning; ToF-SIMS; Apt; Atr-Ftir; S-Xps Band edge Complementary Metal Oxide Semiconductor (CMOS) devices are obtained by insertion of a thin LaOx layer between the high-k (HfSiO) and metal gate (TiN). High temperature post deposition anneal induces Lanthanum diffusion across the HfSiO towards the SiO2 interfacial layer, as shown by Time of Flight Secondary Ions Mass Spectroscopy (ToF-SIMS) and Atom Probe Tomography (APT). Fourier Transform Infrared Spectroscopy in Attenuated Total Reflexion mode (ATR-FTIR) shows the formation of La-O-Si bonds at the high-k/SiO2 interface. Soft X-ray Photoelectron Spectroscopy (S-XPS) is performed after partial removal of the TiN gate. Results confirm La diffusion and changes in the La chemical environment. 0167-9317 no NU @ karnesky @ 11170
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Kruska, Karen; Lozano-Perez, Sergio; Saxey, David W.; Terachi, Takumi; Yamada, Takuyo; Smith, George D.W. Nanoscale characterisation of grain boundary oxidation in cold-worked stainless steels Journal Article 2012 Corrosion Science 63 225-233 A. Stainless steel; B. Tem; C. Oxidation Atom-probe tomography was employed to characterise specimens containing the oxidised part of a grain boundary from a 304 stainless steel coupon specimen exposed to simulated PWR primary water. A TEM foil containing part of the same oxidised grain boundary was also extracted and characterised for comparison. Surface and grain boundary oxide compositions were identified and Ni enrichment was observed around the oxides. The data provides novel information on the role of the minor impurities and the formation of early-stage oxides. These studies were conducted as part of a broader investigation of the mechanisms underlying stress corrosion cracking in stainless steels. 0010-938x no NU @ karnesky @ 11392
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