bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modifications of Surface Microstructure and Properties Induced by High Current Pulsed Electron Beam (HCPEB) Treatments of Intermetallics
Authors: Grosdidier Thierry , Zou Jianxin , Ji Gang , Zhang Kemin , Zhang Xiangdong , Hao Shengzhi , Dong Chuang 
Published: June 2019

AbstractHigh current pulsed electron beam (HCPEB) is a fairly new technique for surface modifications. The present contribution reviews some recent insights on the microstructure modifications encountered at the top surface of HCPEB treated (NiTi and FeAl) intermetallics. In particular, the potential of the technique for structure modifications associated with the use of the pulsed electron beam under “heating” and “melting” conditions is highlighted. The interesting surface modifications include the creation of an homogeneous protective layer under the melting mode while thermal stresses under the heating mode can induce surface hardening and stress enhanced rapid solid state alloying.
Internal Structure of B19 Martensite in AuTi Shape Memory Alloy
Authors: Inamura Tomonari , Tachi Ryosuke , Wakashima Kenji , Hosoda Hideki 
Published: June 2019

AbstractInternal twin of B19 martensite in equiatomic AuTi binary alloy was examined by conventional transmission electron microscopy observation and the phenomenological theory of martensite crystallography (PTMC). The crystal structure of martensite was B19 (orthorhombic) with the lattice parameters of 0.2944nm, 0.4900nm and 0.4633nm. Most of martensite plates were internally twinned by {111}typeI twin. <211>typeII twin was occasionally observed and {011}compound-twin relationship was observed at boundaries between adjacent martensite plates. However, no martensite plate entirely twinned by the <211>typeII twinning or the {011}compound twinning was observed. PTMC analysis showed that the invariant plane is formed only by the introduction of the internal twin of {111}typeI or <211>typeII twin in the present geometry of the transformation. Geometry of a typical martensite plate with internal twin of {111}typeI twin was in good agreement with that required for the formation of habit plane with the invariant plane character. The observed {111}typeI twin is, therefore, considered to be the lattice invariant shear to minimize the elastic strain energy due to the transformation.
Change in Creep Deformation of PST Crystals with Different Stress Axes
Authors: Min Xiaohua , Sakurada Eisaku , Takeyama Masao , Matsuo Takashi 
Published: June 2019

AbstractBased on our analysis of a lot of creep rate-strain curves of PST crystals with the different angles between the lamellar plate and the stress axis, designated as ø, it was confirmed that the creep rate and the creep deformation manner strongly depend on the ø. It was supposed that the predominant creep deformation using γ plate during the transient stage is derived by the fully suppression of the operation of another slip systems not parallel to γ plate through α2 plate. It was also confirmed that the initial stress axes of the PST crystals within the standard stereographic triangle move for the [001]-[111] line, and then turn their directions for [111] pole during the transient stage. This moving manner of the stress axis indicated that the first slip system of [101](111) continues to the area near the [001]-[111] line in the standard stereographic triangle, and then, the second slip system of [110](111) operates. By comparing this moving manner to the creep rate-strain curve, it is suggested that the first slip system of [101](111) operates during the Stage I where the light decrease in the creep rate remains, after that, the second slip system of [110](111) appears and leads to steep decrease in the creep rate. This stage was designated as the Stage II. According to this conception, it is supposed that the strain at the end of the Stage I is directly correlated with the angle from the initial stress axis to the [001]-[111] line in the standard stereographic triangle. In this study, this supposition was confirmed by conducting the creep tests at 1148 K/68.6 MPa using two PST crystals with ø of 31° and 34°. The initial stress axis of the PST crystal with ø of 31° locates nearer to the [001]-[-111] line than that of the PST crystal with ø of 34°. The strain at the end of the Stage I of the PST crystal with ø of 31° is half that of the PST crystal with ø of 34°. By analyzing the inverse pole figures of the creep interrupted PST crystals, it was confirmed that the angle from the initial stress axis to the [001]-[111] line is correlated with the strain of the transient stage.
High Temperature Sulfidation Resistance of DO3 - Ordered FeAl Tested in H2S-rich Gases
Authors: Thery Pierre-Yvan , Fraczkiewicz Anna , Genevois Cecile , Longaygue Xavier , Ropital Francois 
Published: June 2019

AbstractThe sulfidation behaviour at 973 K in a 30 vol.% H2S-H2-H2O-N2 gas mixture of Fe-25 % at. Al, DO3-ordered alloys, binary or alloyed with niobium, was investigated. Binary alloys presented a quite good sulfidation resistance in comparison with 321 stainless steel, even if a large amount of iron sulfides FeS grew over the alumina layer on corroded samples. The sulfidation resistance of DO3 alloys could be significantly improved by an oxidation treatment prior to corrosion test. The Nb in iron aluminides was supposed to preferably react with S and therefore, to enhance sulfidation resistance through preventing the nucleation and growth of harmful FeS. Unfortunately, the scales of Nb-allloyed FeAl contained only a small amount of Nb3S4 which did not prevent efficiently the formation of iron aluminides FeS. Adding Nb to Fe-25Al even resulted in a severe deterioration of the microstructure during sulfidation due to intense diffusion of S inward the sample.
Synthesis of Magnetic Nanoparticles by Sputtering
Authors: Miyata Mai , Kishida Kyosuke , Tanaka Katsushi , Inui Haruyuki 
Published: June 2019

AbstractThe influence of experimental condition on morphology of FePt and Sm-Co nanoparticles synthesized by sputtering in a relatively high gas pressure has been studied. The sputtering apparatus is equipped with an annealing furnace that enables pre-deposition annealing of the nanoparticles. The effect of the annealing temperature on the ordering to the L10 FePt nanoparticles was also investigated. The morphology of the particles depends on a gas pressure and gas flow rate, but the sensitivity to experimental condition differs between FePt and Sm-Co. The morphology and domain structure of FePt nanoparticle are relatively the same in a wide range of experimental condition, whereas those of Sm-Co nanoparticle are significantly changed by variation of a gas pressure. FePt nanoparticles annealed in the annealing furnace prior to their deposition onto the substrate have the ordered L10 phase, which has an advantage for producing a magnetic recording media.
Anisotropic Microstructure and Hydrogen Permeability of Nb-Ti-Ni Duplex Phase Alloy Prepared by Hot Forging-Rolling Technique
Authors: Tokui Sho , Ishikawa Kazuhiro , Aoki Kiyoshi 
Published: June 2019

AbstractIt has been demonstrated that the as-cast Nb40Ti30Ni30 duplex phase alloy, which consists of the primary (Nb, Ti) solid solution and the fine lamellar type eutectic {TiNi+(Nb, Ti)} phase, shows higher hydrogen permeability ¶ than that of pure Pd without the hydrogen embrittlement at 673K. In this alloy, the eutectic phase contributes to the suppression of the hydrogen embrittlement, while the primary one does mainly to the hydrogen permeation. It is important to note that even if the eutectic microstructure disappears and is replaced by the small spherical (Nb, Ti) phase embedded in the TiNi matrix by rolling and subsequent annealing, its high hydrogen permeability and large resistance to the hydrogen embrittlement are sustained. Furthermore, the present authors have observed that the primary (Nb, Ti) phase is largely elongated along the rolling direction. Consequently, it is expected that rolled and annealed Nb-Ti-Ni alloys show the large anisotropy of the microstructure and the hydrogen permeability. In the present work, the microstructure and hydrogen permeability ¶nof the Nb40Ti30Ni30 alloy after rolling and annealing treatments are examined in order to develop highly hydrogen permeable alloys utilizing the anisotropic microstructure.The primary (Nb, Ti) phase and the very fine eutectic {TiNi+(Nb, Ti)} phase are observed in the as-cast Nb40Ti30Ni30 alloy by scanning electron microscopy (SEM). The X-ray diffractometry (XRD) indicates that this alloy consists of the B2-TiNi intermetallic compounds and the bcc- (Nb, Ti) solid solution. The primary (Nb, Ti) phase is largely elongated along the rolling direction by forging and subsequent rolling at 1173 K. On the other hand, the eutectic microstructure becomes unclear with increasing the rolling reduction. The composite alloys in which the (Nb, Ti) phase is elongated along to the rolling direction are obtained by 69 % rolling reduction. ¶n of this sample is four times higher than that of as-cast one. On the other hand, ¶ for the sample vertical to the rolling direction is reduced to about one third of that of as-cast one. Thus, the hydrogen permeability of the Nb40Ti30Ni30 alloy varies about ten times or more depending on the direction of the primary¡]Nb, Ti¡^ phase. We conclude that it is possible to produce highly hydrogen permeable Nb-Ti-Ni alloys using the anisotropy of the microstructure prepared by hot forging and rolling.
Crack Growth Behavior in a Two-Phase Mo-Si-B Alloy
Authors: Kumar Sharvan , Alur Amruthavalli Pallavi 
Published: June 2019

AbstractMo-rich Mo-Si-B multiphase alloys are currently being explored for their potential as high-temperature structural materials for components in hot sections in aircraft engines. In this paper, we present crack growth behavior in one such two-phase alloy consisting of a Mo solid solution matrix in which is dispersed approximately 40 volume percent of the Mo5SiB2 (T2) phase. Crack growth under monotonic and cyclic loading is considered over a temperature range spanning 20°C to 1400°C. The effects of loading rate (in monotonic loading) and dwell times at maximum stress (in cyclic loading) at high temperatures on crack growth were examined to understand the contribution from creep. Results confirm a gradual increase in fracture toughness upto 1000°C, beyond which the increase is more substantial with temperature; fatigue susceptibility was also observed in excess of 900°C and crack-tip-stresses-driven microstructural instability is evident at 1400°C. At this temperature, slow loading rates or dwell times at maximum stress lead to crack-tip recrystallization and creep cavitation that together degrade the material's properties.
High Temperature Deformation Behavior of a Mechanically Alloyed Mo Silicide Alloy
Authors: Heilmaier Martin , Saage Holger , Jéhanno Pascal , Böning Mike , Freudenberger Jens 
Published: June 2019

AbstractA 3-phase Mo-Si-B alloy consisting of Mo solid solution and the intermetallic phases Mo3Si and Mo5SiB2 (T2) was manufactured employing mechanical alloying (MA) as the crucial processing step. After consolidation via cold compaction, sintering in hydrogen atmosphere and final hot isostatic pressing (HIP) at 1500°C, one obtains an ultra-fine microstructure with a nearly continuous Mo(ss) matrix and the sizes of all phases being in the 1 micron range. Tensile tests were carried out in vacuum at initial strain rates ranging from 10-4 to 10-2 s-1 and the temperature varied between n1200 an 1400 °C. With a stress exponent of about 2 and the activation energy being close to that of Mo-self diffusion the material exhibits superplasticity at temperatures as low as 1300°C and tensile strain to failures up to 400%, thus, making sound wrought processing on industrial-scale facilities at temperatures typical for refractory metals and alloys feasible. To enhance creep resistance at high temperatures the alloys were annealed at 1700°C for 10h for a coarsening of the microstructure. While, still, the average sizes of all phases were below 10 microns, a considerable reduction in minimum creep rate was noted. This finding also demonstrates the extraordinary high thermal stability of this 3-phase Mo-silicide alloy.
Role of Thermal Expansion and Redistribution of Components on the Temperature Dependence of the Lattice Misfit in γ/γ' Superalloys
Authors: Kontsevoi Oleg , Gornostyrev Yuri N. , Freeman Arthur J. 
Published: June 2019

AbstractThe relative role of thermal expansion and redistribution of alloy components in the temperature dependence of the lattice misfit in γ/γ' alloys is investigated on the basis of ab initio calculations. We show that in a wide temperature region up to approximately 0.6·Tmelt, the lattice misfit is determined by the difference in thermal expansion of γ and γ' phases and shows only a slight variation. For higher temperatures the redistribution of the major alloy components between the phases becomes a leading contribution to the lattice misfit.
First Principles Calculations of Helium Solution Energies in BCC Transition Metals
Authors: Willaime François , FU Chu Chun 
Published: June 2019

AbstractDensity functional theory calculations of the solution energies of helium in substitutional, tetrahedral and octahedral sites have been performed for all BCC transition metals: V, Nb, Ta, Cr, Mo, W and Fe. The effects of exchange correlation functional and of pseudopotential have been investigated in Fe; they are relatively small. The solution energies are found to be weakly dependent on the element for the substitutional site whereas for the interstitial sites they are much smaller in group V than in group VI and they decrease from 3d to 4d and 5d metals. As a result an inversion is observed from V, Nb and Ta - which tend to favor the interstitial site - to Mo and W, which favor the substitutional one, with an intermediate behavior for Cr and Fe. Finally, the results indicate that the tetrahedral site is always energetically more favorable than the octahedral one by 0.2 to 0.3 eV.
Atomistic Simulations of Displacement Cascades in Fused Silica: It is Compared with Different Concentration of H in the Bulk
Authors: Mota Fernando , Caturla Maria Jose , Perlado Jose Manuel , Ibarra Angel , Molla Joaquin 
Published: June 2019

AbstractAmorphous Silica is one of candidate materials for both final focusing optics of lasers for NIF and future inertial fusion reactors and diagnostics of the Safety and Control Systems of the ITER machine as well as DEMO magnetic fusion reactors. In operation, these materials will be exposed to high neutron irradiation fluxes and it can result in point defect and vary the optical absorption, that is, degradation of the optical properties. In this paper we present molecular dynamic simulation of displacement cascade due to energetic recoils in amorphous silica without hydrogen atoms and with 1% of hydrogen atoms trying to identify defects formation. We have made a statistics of the different kind of defects at different energy of primary knock-on atoms (PKA). The range of studied PKA energies are from 400 eV to 3.5 keV and it is made to both component of this material Silicon and Oxygen.
Comparative Study of Structural Damage Under Irradiation in SiC Nanostructured and Conventional Ceramics
Authors: Leconte Yann , Monnet Isabelle , levalois Marc , Morales Magali , Portier Xavier , Thomé Lionel , Herlin-Boime Nathalie , Reynaud Cecile 
Published: June 2019

AbstractIn the context of research on new materials for next generation nuclear reactors, it becomes more and more interesting to know what can be the advantages of nanostructured materials for such applications. In this study, we performed irradiation experiments on microstructured and nanostructured â-SiC samples, with 95 MeV Xe and 4 MeV Au ions. The structure of the samples was characterized before and after irradiation by grazing incidence X ray diffraction and Raman spectroscopy. The results showed the occurrence of a synergy between electronic and nuclear energy loss in both samples with 95 MeV Xe ions, while the nanostructured pellet was found to have a better resistance to the irradiation with 4 MeV Au ions.
Reactive Deposition of Dielectrics by Ion Beam Assisted E-beam Evaporation
Authors: Nightingale Joshua , Cornell T. , Samudrala P. , Poloju P. , Hornak L. A. , Korakakis D. 
Published: June 2019

AbstractFabrication of high index contrast waveguide stacks for biosensing and other applications require nanometer scale thickness control. Nanoscale dielectric films from electron-beam evaporation can be difficult to obtain due to the resulting porosity and poor stoichiometry of the films. An alternative approach is the reactive deposition of the film from a metal source in the presence of oxygen ions. Using spectroscopic ellipsometry, we have shown that greater control over thickness and index of refraction of silicon dioxide depositions can be obtained through reactive depositions as compared to depositions from SiO2 dielectric source material itself. Through Fourier Transform Infrared Spectroscopy (FT-IR), the Si-O in-phase stretching peak at 1078 cm-1 can be traced, allowing us to determine the stoichiometry of the film.The effects of performing depositions of aluminum oxide dielectric source material in the presence of oxygen ions has also been investigated. Through the use of the oxygen ion source, greater control over index of refraction and optical losses has been observed. By controlling ion source parameters, the aluminum oxide films’ index of refraction can be engineered within a range of 1.58 to 1.64, and waveguide losses can be reduced to as low as 2.0 dB/cm.
Indentation-Induced Damage Mechanisms in Germanium
Authors: Oliver David J , Bradby Jodie E , Williams Jim S , Swain Michael V , McGrouther Damien , Munroe Paul 
Published: June 2019

AbstractThe response of crystalline Ge to indentation has been studied over a range of maximum loads. At a certain load, an unusual ‘giant pop-in’ event occurs, in which a discontinuous extension of >1 μm is observed in the force-displacement curve. In such cases, load release curves show a pronounced ‘elbowing’ response, leading to increased depth recovery. TEM and Raman microspectroscopy revealed the presence of amorphous material in the residual impression. To examine cracking, a sequence of cross-sections was milled through the indent and images taken using an automated method (the ‘slice-and-view’ method). Using 3-D reconstruction software, the data was segmented and reconstructed into a 3-dimensional representation of the cracks around the indent. Applying this technique to indents featuring a giant pop-in, it was deduced that the inelastic elbowing observed was a bending response of material detached by lateral cracking. The giant pop-in is attributable to material removal, caused by lateral cracks formed during loading.
Development of Hybrid MEMS/FIB Processes and Applications of Three-pronged Active Nanotweezers For Manipulation of Nano Objects
Authors: Wang Xuefeng , Liu Chang 
Published: June 2019

AbstractWe report recent development of a three-probe micromachined nanomanipulator for manipulation and in-situ characterization of nanomaterials in scanning electron microscope (SEM). The nanomanipulator consists of three independent probes having thermal bimetallic actuators and nanoscopic end-effectors. Nanoscale end-effectors with sub-100-nm spacing are created using focused ion beam (FIB) milling to directly interface with nanoscopic objects (e.g., nanotubes, nanowires). Handling of individual carbon nanotubes (CNTs) was successfully realized with the nanomanipulator in an SEM.
Residual Stress of Focused Ion Beam-Exposed Polycrystalline Silicon
Authors: Archuleta Kim M. , Adams David P. , Vasile Michael J. , Fulghum Julia E. 
Published: June 2019

AbstractMedium energy (30 keV) focused gallium ion beam exposure of silicon results in a compressive in-plane stress with a magnitude as large as 0.4 GPa. Experiments involve uniform irradiation of thin polysilicon microcantilevers (200 micron length) over a range of dose from 1 x 1016 to 2 x 1018 ions/cm2. The radii of curvature of microcantilevers are measured using white light interferometry before and after each exposure. The residual stress is determined from these radii and other measured properties using Stoney's equation. The large residual stress is attributed to ion beam damage, microstructural changes and implantation.
Actinide Co-Conversion by Internal Gelation
Authors: Robisson Anne-Charlotte , Dauby Jacques , Dumont-Shintu Corinne , Machon Estelle , Grandjean Stéphane 
Published: June 2019

AbstractSuitable microstructures and homogenous microspheres of actinide compounds are of interest for future nuclear fuel or transmutation target concepts to prevent the generation and dispersal of actinide powder. Sol-gel routes are being investigated as one of the possible solutions for producing these compounds. Preliminary work is described involving internal gelation to synthesize mixed compounds including minor actinides, particularly mixed actinide or mixed actinide-inert element compounds. A parameter study is discussed to highlight the importance of the initial broth composition for obtaining gel microspheres without major defects (cracks, craters, etc). In particular, conditions are defined to produce gel beads from Zr(IV)/Y(III)/Ce(III) or Zr(IV)/An(III) systems. After gelation, the heat treatment of these microspheres is described for the purpose of better understanding the formation of cracks after calcination and verifying the effective synthesis of an oxide solid-solution.
Synthesis of Porous Materials via Multiscale Templating Approaches: Emulsions, Nanoparticles, Supercritical Fluids, and Directional Freezing
Authors: Zhang Haifei , Hussain Irshad , Long James , Tan Bien , Brust Mathias , Rosseinsky Matthew , Rannard Steven , Butler Michael , Cooper Andrew 
Published: June 2019

AbstractA “toolkit” of emulsion templating and directional freezing methods has been developed which allows the preparation of a wide variety of organic, inorganic, and metallic materials in a macroporous or hierarchically porous form.1,18,20 The various processes use water, organic solvents, or aqueous/organic emulsions as the template phase. We have shown that the organic solvent can be replaced by liquid CO2 in both the emulsion templating and directional freezing approaches, thus reducing organic waste and offering advantages in applications such as the preparation of biomaterials.
New Low-Dimensional Iron(II) Phosphates Exhibiting Field-Dependent Magnetization Steps
Authors: Hwu Shiou-Jyh , Queen Wendy L. , Wang Lei , Ranmohotti K. G. Sanjaya 
Published: June 2019

AbstractA new family of transition-metal-containing phosphates ANa3M7(PO4)6, where A = K, Rb, Cs and M = Mn, Fe, Co, was synthesized via high-temperature (650-800 °C), solid state reactions. Sizable single crystals up to 1 cm (ca. 160 mg) were grown for structure and property characterization. The extended structure comprises of alternating corner- and edge-sharing triangular chains of FeOn (n = 5,6) polyhedra involving four crystallographically distinct Fe(II) cations. The triangular chains propagate along the a and b directions to form slabs, which are interlinked by P5+ and a fifth Fe2+ cation to form the three-dimensional lattice. The magnetic susceptibility studies suggest that some of these fascinating compounds exhibit a ferromagnetic transition at temperatures between 10K and 15K. The field-dependent studies on the oriented single crystal of RbNa3M7(PO4)6 show the occurrence of magnetization steps at 2	-5K. In this report, we will first discuss some prior research developments relevant to the study of geometrically frustrated magnetic (GFM) interactions, followed by the results of our exploratory synthesis in the pseuo-quaternary iron(II) phosphate system and finally some initial investigations of temperature- and field-dependent magnetic properties.