bluuebunny/crossref_metadata_2025 huggingface dataset:
A Gold-Based Bulk-Solidifying Amorphous Alloy for Jewelry — Comparison with a Palladium-Based Amorphous Alloy
Authors: Cardinal Sandrine , Qiao Ji Chao , PELLETIER Jean-Marc
Published: May 2014

The gold alloys are used in jewelry for their aesthetic appearance and inertia to the environment. In jewelry a hardness superior to 300 HV is desirable to facilitate the final machining and reduce the wear of the final product. The maximum hardness that can be obtained with the standard 18 carats gold (Au75-Ag12.5-Cu12.5 (wt%)) through a combination of heat treatment and cold working is about 290 HV. Gold-based bulk metallic glasses (BMGs) are an alternative as they present unique properties in comparison with crystalline counterparts, especially easy thermoplastic processing combined with a high hardness. Pd-base BMGs are another solution, due also to their attractive features.An Au49Cu26.9Si16.3Ag5.5Pd2.3 (% at.) and a Pd40Cu30Ni10P20 (% at.) bulk metallic glasses were fabricated by a copper mould suction casting technique in an argon atmosphere. In the as-cast state hardness, shear modulus and hardness are high (HV0.3= 360 and 530 in the Au-and Pd-base BMGs, respectively). Various heat treatments have been performed to modify the microstructural state. Formation of crystalline particles induces an increase of both shear modulus and hardness but a drastic decrease in toughness and therefore this formation should be absolutely avoided during casting or thermo processing.
Monolithic Nanoporous Copper with Novel Electrochemical Properties Fabricated by Dealloying Cu-Zr(-Al) Metallic Glasses
Authors: Qin Chun Ling , Wang Zhi Feng , Liu Hui , Liu Li , Wang Hao , Ding Jian , Zhao Wei Min
Published: May 2014

Monolithic uniform nanoporous Cu (NPC) ribbons with a ligament/pore size of 10-25 nm are successfully synthesized by chemical dealloying the Cu50Zr50 and Cu50Zr45Al5 metallic glasses in 0.5 M HF for 7 min. It is found that the length scale of ligaments/channels can be tuned by simply alloying 5 at.% Al to the Cu-Zr binary glassy alloys. The current signal of the NPC-supported MnO2 composite electrode is remarkably enhanced as compared to that of pure MnO2 powders. These new findings greatly raise the hope for possible applications of NPC as a new type of electrode substrates or an advanced sensor in green and new energy technology.
Mg-Based Bulk Amorphous Alloy Composites Fabricated by Spark Plasma Sintering
Authors: Qin Feng Xiang , Dan Zhen Hua , Xie Guo Qiang
Published: May 2014

By using the Mg65Zn30Ca5 amorphous powder prepared by ball-milling of the master alloy or its mixture powders, we produced Mg65Zn30Ca5 bulk amorphous alloy and its composites by a spark plasma sintering process. The microstructure and corrosion properties of the prepared Mg65Zn30Ca5 bulk amorphous alloy and its composites were investigated. The bulk amorphous alloy and its composites exhibited a high relative density and high corrosion resistance than commercial Mg alloys.
Application of Recrystallization Texture Evolution Model to Predict Plastic Formability in Steel Strips
Authors: Morimoto Toshiharu , Fuyuki Y. , Yanagida A. , Yanagimoto Jun
Published: May 2014

T.M.C.P.(Thermo Mechanical Control Processing) has been widely used to improveplastic formability in steel strips. We have produced interstitial free steel(IF steel) strips and ferriticstainless-steel strips through T.M.C.P. rolling method. Optimizing conditions of hot rolling, hotrolled annealing, cold rolling and cold rolled annealing, we developed texture prediction model. Wecan predict rolling texture accurately using the conventional Taylor model. Moreover, we preciselypredict recrystallization texture classifying the total number of microscopic slips which arecalculated using the Taylor model. We consider that these calculated results provednucleation-oriented model and two types of recrystallization and grain growth mechanisms exit inour studies. One mechanism is that grains which had the small total number of microscopic slips arepreferred orientation for the hot rolled and annealed ferritic stainless-steel strip. The othermechanism is that grains which had the high total number of microscopic slips are preferredorientation for the cold rolled and annealed IF steel strip.
Cu Particulates Dispersed Bulk Metallic Glass Composites with High Strength and High Electrical Conductivity Fabricated by Spark Plasma Sintering
Authors: Xie Guo Qiang , Qin Feng Xiang , Kimura Hisamichi
Published: May 2014

Using the mixed powders containing gas-atomized powders of metallic glassy alloys (Cu50Zr45Al5, Fe73Si7B17Nb3, Ni52.5Nb10Zr15Ti15Pt7.5) blended with high-conductive Cu particulates, we produced bulk metallic glassy alloy composites with high strength and high electrical conductivity, as well as with enhanced plasticity and satisfying large size requirements by a spark plasma sintering process. In this paper we present and review our research results on the fabrication and properties of the bulk glassy alloy composites by the spark plasma sintering process.
Bottom-Up Formation of Vertical Free-Standing Semiconductor Nanowires Hybridized with Ferromagnetic Nanoclusters
Authors: Hara Shinjiro
Published: May 2014

The author introduces and summarizes the results on bottom-up formation and structural characterizations obtained so far for the MnAs nanoclusters and MnAs/semiconductor nanowire hybrids. First, MnAs nanoclusters were grown by selective-area metal-organic vapor phase epitaxy. They had a hexagonal NiAs-type crystal structure. Their <00(0)1> direction was parallel to <111>B direction of zinc-blende-type GaAs substrates. Hybrid MnAs/GaAs nanowires, subsequently, were fabricated by combining selective-area metal-organic vapor phase epitaxy of GaAs nanowire templates and endotaxial MnAs nanoclustering on them. MnAs nanoclusters ordered at six ridges of hexagonal GaAs nanowires were formed possibly owing to more atomic steps between {0-11} crystal facets. In the case of hybrid MnA/InAs nanowires, MnAs nanoclusters were not formed only on the {0-11} side-walls, and/or ridges between them, but on the top {111}B crystal facets of hexagonal InAs nanowires. MnAs nanoclusters were formed much deeper into the InAs nanowires than into the GaAs nanowires. These facts are possibly due to the InAs nanowires are thermally less stable than the GaAs nanowires. Some of the hybrid MnA/InAs nanowires were bent at the parts where the MnAs nanoclusters were grown into the host nanowires mainly owing to the strain effects.
III-V/Ge Device Engineering for CMOS Photonics
Authors: Takenaka Mitsuru , Takagi Shinichi
Published: May 2014

Heterogeneous integration of III-V compound semiconductors and Ge on the Si platform is one of the promising technologies for enhancing the performance of metal-oxide-semiconductor field effect transistors (MOSFETs) beyond the 10-nm technology node because of their high carrier mobilities. In addition, the III-Vs and Ge are also promising materials for photonic devices. Thus, we have investigated III-V/Ge device engineering for CMOS photonics, enabling monolithic integration of high-performance III-V/Ge CMOS transistors and III-V/Ge photonics on Si. The direct wafer bonding of III-V on Si has been investigated to form III-V on Insulator for III-V CMOS photonics. Extremely-thin-body InGaAs MOSFETs with the gate length of approximately 55 nm have successfully been demonstrated by using the wafer bonding. InP-based photonic-wire waveguide devices including micro bends, arrayed waveguide gratings, grating couplers, optical switches, and InGaAs photodetectors have also been demonstrated on the III-V-OI wafer. The gate stack formation on Ge is one of the critical issues for Ge MOSFETs. Recently, we have successfully demonstrated high-quality GeOx/Ge MOS interfaces formed by thermal oxidation and plasma oxidation. High-performance Ge pMOSFET and nMOSFET with thin EOT have been obtained using the GeOx/Ge MOS interfaces. We have also demonstrated that GeOx surface passivation is effective to reduce the dark current of Ge photodetectors in conjunction with gas-phase doped junction. We have also investigated strained SiGe optical modulators. We expect that compressive strain in SiGe enhances modulation efficiency, and an extremely small VπL of 0.033 V-cm is predicted. III-V/Ge heterogeneous integration is one of the promising ways for achieving ultrahigh performance electronic-photonic integrated circuits.
Role of the Tilting of Oxygen Octahedra in the Stabilization of the Orbital-Modulated State in the Layered Perovskite Manganite Ca2-xNdxMnO4
Authors: Inoue Yasuhide , Arao Masazumi , Tanaka Ippei , Koyama Yasumasa
Published: May 2014

There exists the orbital-modulated (OM) state in the layered manganite Ca2-xNdxMnO4 (CNMO) with 0.20 ≤ x ≤ 0.50. To understand the effect of the tilting of MnO6 octahedra to the stability of the OM state, the crystallographic features of CNMO samples prepared by a solid-state reaction have been investigated mainly by transmission electron microscopy. For 0.30 ≤ x ≤ 0.50, it was found that the (LTO → Pccn/LTT) structural transition occurred on cooling from room temperature, where the LTO and Pccn/LTT structures are, respectively, characterized by tilting displacements of oxygen octahedra about one and two of the <110> directions. The notable feature of the (LTO → Pccn/LTT) transition is that its progress strongly suppresses the growth of the OM state for 0.30 ≤ x ≤ 0.45. As a result of the suppression, the OM state exhibits a re-entrant behavior for its appearance. This is an indication that the Pccn/LTT tilting is not favorable for the stabilization of the OM state.
Recent R&D on Superconducting Wires for High-Field Magnet
Authors: Jin Xin Zhe , Nakamoto Tatsushi , Tsuchiya Kiyosumi , Yamamoto Akira , Ogitsu Toru , Sugano Michinaka , Harjo Stefanus , Abe Jun , Gong Wu , Iwahashi Takaaki , Kikuchi Akihiro , Takeuchi Takao , Yanagisawa Yoshinori , Takahashi Masato , Maeda Hideaki
Published: May 2014

Development for superconducting wires of materials such as Nb3Al and the high-temperature superconductors (HTS such as REBCO, Bi2223, and Bi2212) has been carried out for high-field magnet applications. It is known that these types of wire exhibit very different characteristics and performance for different applications. The development of Nb3Al wire for high-field accelerator magnet has resulted in remarkable achievements in critical current using a Rapid Heating and Quenching (RHQ) method by High Energy Accelerator Research Organization (KEK) and National Institute for Materials Science (NIMS). As one example of a characteristic of Nb3Al, the strain sensitivity of the critical current in the RHQ-Nb3Al wire is better than that of Nb3Sn wire. A strain study is needed to further the development of a high-filed magnet; therefore, we have carried out experimental studies using the neutron diffractometer at J-PARC Takumi. Researchers have recently achieved the highest critical current density for REBCO wires in a high-field above 15 T. For this reason, REBCO wire has been considered for high-field magnet NMR applications in Riken. But several obstacles remain, including coil degradation, shielding current and thermal runaway. In this paper, R&D on recent advances for applications will be presented.
Local Brittle Zones and the Role of Niobium
Authors: Bhadeshia Harshad K.D.H.
Published: May 2014

There is a confused and contradictory literature on the role of small concentrationsof niobium on the development of the so-called local brittle zones in steels. These zones consistof a mixture of martensite and austenite and hence, their formation should be predictable usingmodern microstructure calculation methods. Following an assessment of the most relevant literature,a mathematical model is presented which enables three quantities to be calculated, the fractionof martensite, the carbon concentration of the martensite, and its ability to inﬂuence toughness.Examples are presented for particular linepipe steels, and then the generic eﬀect of alloying elementsother than niobium, on the development of local zones.
Comparative Analysis by the Newton Method of New Constitutive Strain Dependent Creep Equations Based on the Garofalo Equation
Authors: Carsí Manuel , Gutiérrez Victor , Rieiro Ignacio , Benavente Esther , Ruano Oscar A.
Published: May 2014

The improvement of optimization numerical methods for constitutive equations has been the first aim of this research. A subordinate optimization algorithm, based on Newton method, through “ad hoc” assessment, has been developed. Application to hot torsion data of AISI4145 with two grain sizes has been carried out. It is concluded that the Newton method is an excellent algorithm for the optimization of strain dependent constitutive equations. Two models are presented as alternative to the generalized Garofalo model: the normalized stress exponent model (NSE) and the Generalized Sherby model (SG). The NSE model is the most precise to restitute the experimental stress-strain curves.
Predicting the Microstructural Evolution of an Austenitic Stainless Steel by Hybrid Modeling
Authors: Johnsson Andreas , Karlberg Mats
Published: May 2014

During the annealing heat treatment following cold rolling of a 304L austenitic stainless steel sheet material, the material goes through changes in microstructure and mechanical properties. The cold rolling history together with the time/temperature trajectory in the annealing furnace can be used to model the final microstructure. In this work, physically based models for recrystallization and the following grain growth was created for the prediction of the microstructure evolution-both grain size and grain size distribution-, and an artificial neural network, ANN, was added for secondary effects. This is more commonly referred to as a hybrid model. The microstructure hybrid model was tested and validated against cold rolled and annealed production sheet material of various thicknesses and reductions, where the grain size and grain size distribution was measured by Electron Back Scatter Diffraction, EBSD. The recrystallization and grain growth parameters and functionality were fitted for non-isothermal conditions, against experimental tests of cold rolled material. Given process history and time/temperature data from the annealing heat treatment, the model can predict the microstructure, average grain size and grain size distribution with high accuracy and the executing time is short which makes it suitable for in-line use.
Thermo-Mechanically Coupled Modeling of Cooling Temperature History Effects on Precipitation Hardening in Hot Strip Coiled Products
Authors: Karlberg Mats
Published: May 2014

When producing hot strip, HSLA(High Strength Low Alloyed) products the coiling temperature and the subsequent coil cooling is of great importance for the final mechanical properties. A thermo-mechanically coupled model has been developed where the anisotropic stress dependent thermal properties caused by the layered structure and the asymmetric cooling are included. Additionally the precipitation hardening effect on the yield strength, influenced by the thermal history during cooling was compared with mechanical tensile testing along the strip length at SSAB EMEA works in Borlänge, Sweden. Good agreement between measured and predicted yield stress variations in head and tail was obtained.
Modeling of Hydrogen Diffusion in Piled Slabs
Authors: Sidestam Patrik , Karlberg Mats , Niska John
Published: May 2014

Hydrogen is harmful in steel which makes it important to reduce the hydrogen content. Piling slabs after casting gives a slow cooling which increases the diffusion out of the steel. Finite element modeling has been used to simulate this process where hydrogen solubility and phase dependent diffusivity can be taken into account. The hydrogen diffusion model is using STEELTEMP® 2D for the thermal analysis. Measurements of temperature and hydrogen content in piled slabs have been done and the calculations are in good agreement.
Energy Dissipation and Self-Heating due to Microplastic Deformation Mechanisms at Very High Cycle Fatigue for Single-Phase Ductile Metals
Authors: Favier Véronique , Blanche Antoine , Phung Ngoc Lam , Ranc Nicolas , Chrysochoos André
Published: May 2014

This paper aims at a deeper understanding of mechanisms leading to crack initiation in ductile metals in Very High Cycle Fatigue (VHCF). The VHCF regime is associated with stress amplitudes lower than the conventional fatigue limit and numbers of cycles higher than 109. Tests were conducted using an ultrasonic technique at loading frequency of 20 kHz. The mechanisms leading to crack initiation express via slip bands at the specimen surface and self-heating due to intrinsic dissipation. Thermal maps were used to estimate the mean dissipation and its change with number of cycles and stress amplitudes in case of pure copper polycrystals. At the same time, the surface relief changes due to plasticity were characterized using optical and scanning electronic microscopes. A good correlation was found between slip band initiation and dissipation. Dissipation and slip band amount always increased over the number of cycles. At very small stress amplitudes, no slip band appeared up to 108 cycles but the material was found to dissipate energy. Results derived from tests performed at high loading frequency on pure cupper specimens showed a drift of dissipative regimes incompatible with concepts of fatigue limit and/or asymptotic cyclic stability. These results reveal that the material never reached a steady state. Therefore it could break at higher number of cycles.
Particle Dispersion Simulator for Gel Printer
Authors: Makino Masato , Kabir M. Hasnat , Gong Jin , Furukawa Hidemitsu
Published: May 2014

We are developing food printer to design arbitrary shaped foods. The ink for the food printer, injected from nozzle to make foods, is the dispersion of rigid and deformable particles. Simulation for rheological properties and interaction among particles and walls could be one of the important tools to develop the ink for the food printer. We introduce our simulators to investigate the dynamics of particles dispersion. The particles are expressed as Lagrange mesh immersed in fluid. The fluid is solved by Lattice Boltzmann method. The viscosity of the dispersion of the rigid and the deformable particles is shown in this study.
Additive Manufacturing Viewed from Material Science: State of the Art & Fundamentals
Authors: Hascoet J.Y. , Karunakaran K.P. , Marya Surendar
Published: May 2014

Additive Manufacturing (AM), also designated as 3D Printing (3DP), is one of the mostvisionary and friendly approaches for flexible manufacturing with conservation of energy andmaterial resources. It is a factory in a box that can generate multiple objects. It requires littlemanpower to bring virtual innovations into the real world. AM for metals can be mechanisticallyassociated with welding. The technique employs a variety of energy sources (laser, electron beam,electric Arc, …), feed stocks (powder, wire and ribbon) and motion kinematics & control(articulated robot and 3-5 axes CNC machine ). From the materials perspectives, akin to fusionwelding in many respects, AM involves a multitude of complex and interacting physical phenomenasuch as heat transfer, fluid flow, discrete and continuum mechanics, sintering, melting,solidification, solid state transformations, grain growth, diffusion, textures etc. The desired processperformance can be achieved by controlling the parameters of energy, feed stock and motion. Theeffect of successive thermal cycles along with the epitaxial relations between substratum anddeposits constitute some of the challenging tasks for developing optimized parts. This paper reviewsthe state of the art and presents some challenges facing metal product development for serviceapplications.
Crystallographic Features of the Relaxor State in the Mixed Ferroelectric System Ba(Ti1-xZrx)O3
Authors: Tsukasaki Hirofumi , Inoue Yasuhide , Koyama Yasumasa
Published: May 2014

The relaxor state has been found in the mixed ferroelectric system Ba (Ti1-xZrx)O3 around x = 0.35. To understand the nature of the relaxor state, the crystallographic features of the paraelectric (PC), ferroelectric, and relaxor states for 0.15 ≤ x ≤ 0.40 have been investigated mainly by transmission electron microscopy. It was found that a microstructure of the ferroelectric state for 0.15 ≤ x ≤ 0.28 consisted of banded structures with boundaries parallel to the {110}PC and {100}PC planes. Based on the Sapriel theory concerning ferroelastic transitions, it was understood that the banded structures were consistent with domain structures in the ferroelectric rhombohedral (FR) state having a polarization vector parallel to one of the <111>PC directions. With the help of the failure of Friedel’s law in diffraction, furthermore, polar regions having <001>PC and <110>PC components of a <111>PC polarization vector were also found to be separately observed in the PC and relaxor states as well as the FR state. Then, in-situ observation for 0.29 ≤ x ≤ 0.40 made in this study indicated that the PC and relaxor states consisted of polar nanometer-sized regions having these two components. Based on this, the relaxor state in BTZ can be identified as an assembly of polar nanometer-sized regions, which were produced by the suppression of the (PC→FR) ferroelectric transition on cooling.
Damage Evolution and Crack Growth in Nickel-Based Alloys during Ultrasonic Fatigue
Authors: Zimmermann Martina , Kolyshkin A. , Stöcker C. , Jones J.W. , Christ Hans-Jürgen
Published: May 2014

Experimental results on the fatigue damage of quasi defect-free materials in the VHCF range are presented. For nickel-based superalloys and pure nickel the likelihood of crack initiation at favorable grain morphologies is studied. Slip band and microcrack formation at the surface was observed even in run-out samples. Hence, microcracks were evaluated regarding their propagation capabilities according to grain orientation and barrier function of grain boundaries. In the VHCF regime crack initiation can shift from surface to subsurface, consequently early crack growth has to be studied by means of optical methods and indirect detection techniques or tomographic methods. In the study presented crack initiation and crack growth was monitored through optical observation and quasi 3-D observation by means of synchrotron radiation. For an as-received and a coarse-grained condition of pure nickel Ni201 fatigue crack growth in the VHCF regime occurs at deltaK as low as 3.54 MPam1/2 for a crack growth rate da/dN = 10E-12 m/cycle. The grain size had no effect on the threshold limit but crack growth retardation at grain boundaries and crack path deflection lead to lower crack growth rates for the coarse-grained condition In the nickel-based alloy Nimonic 80A the influence of microstructure on the intercrystalline crack initiation and propagation was confirmed. Here, the combination of the misorientation angle between two adjacent grains and the orientation of their boundary with respect to the external load defines the magnitude of stress concentration at grain boundaries.
Effects of Sintering Conditions on the Mechanical Properties of Alumina Particle Dispersed Magnesium SPS Compacts
Authors: Kawamori Shigehiro , Fujiwara Hiroshi , Kasuga Yukio
Published: May 2014

To enhance the mechanical properties of Mg alloys, 0-30vol% Al2O3/Mg powders were formed by ball milling powder mixtures of pure Mg and Al2O3 particles, and then Spark plasma sintering (SPS) compacts (Al2O3/Mg discs) were made by the Al2O3/Mg powders. The effect of the cooling conditions in the SPS process on the mechanical properties of the Al2O3/Mg discs was investigated. From the results of SEM, XRD and TEM-EDS, the microstructures of the Al2O3/Mg discs were identified to consist of α-Mg solid solution, Al2O3 particles, refined MgO particles and refined needle-like Mg17Al12 ( more than 20vol% Al2O3 content). The mechanical properties of the discs were able to control by the regulation of the cooling conditions (cooling rate (vc) and applied pressure in the cooling (pc)) in SPS process, and as a result, the SPS discs possessing the mechanical properties beyond HP compacts were obtained under the cooling conditions of “vc= 0.83K/sand pc = 20MPa”. Main factor that the cooling conditions in SPS process effect on the mechanical properties of the Al2O3/Mg discs are considered to be the compresive residual stress generated in the α - Mg solid solution by the thermal stress associated with deference of the coefficients of thermal expansion between the α - Mg and ceramics particles (Al2O3 and MgO) in the discs.
Ti-50.2Ni-5Zr Shape Memory Alloy Square Rots Production by the Casting Technique
Authors: Kitamura K.
Published: May 2014

The purpose of this study is to make the Ti-Ni-Zr specimen using casting method from P/M ingot and evaluates the shape memory behavior. All samples were square rod shape made by centrifugal casting. The size of all samples was 1 mm wide, 1.3 mm height and 37.5 mm length. The transformation behavior during cooling and heating was investigated using a differential scanning calorimeter (DSC). The phase constituent was determined by XRD analysis from 20 °C to 150 °C. Mechanical properties of the shape memory effects were measured using a tensile machine at 25 °C. The samples were annealed at 400 °C, 500 °C and 600 °C for 3.6 ks followed by water quenching. After annealing, specimens were cold rolled at 0 % (no rolling) and 10 %. The Ti-Ni-Zr square rod specimens are fabricated by centrifugal casting using P/M ingot. All samples had shape memory behavior. From DSC measurement, the highest reverse martensitic transformation temperature is 120 °C. From tensile test, the Luders like deformation stress were not constant and dependence of heat treatment conditions was not clarified. However, 10% cold rolling specimen, shape memory characteristics were stabilized.
Preparation of Textured Li1+x-yNb1-x-3yTix+4yO3 Solid Solution in a High Magnetic Field
Authors: Nakano Hiromi , Suehiro Shiho , Suzuki Tohru S.
Published: May 2014

In the Li2O-Nb2O5-TiO2 system, Li1+x-yNb1-x-3yTix+4yO3 (0.06  x  0.33, 0  y  0.09) (LNT) forms with a superstructure, which is the so-called M-phase. In this work, as a first step toward application of the unique qualities of an electro-ceramic with an anisotropic structure, we prepared an oriented LNT balk ceramic by slip casting in a strong magnetic field of 12 T. The direction of the magnetic field was parallel to the casting direction. The compact was densified by cold isostatic pressing and then heated at 1373 K. The obtained specimen was analyzed by X-ray diffraction, scanning electron microscope, and transmission electron microscope. Consequently, the c-axis of the LNT powders was aligned parallel to the magnetic field and a high orientation degree was achieved in a strong magnetic field of 12 T
X-Ray Diffraction Studies on Ti-Pd Shape Memory Alloys
Authors: Arockiakumar Raju , Takahashi Madoka , Takahashi Satoshi , Yamabe-Mitarai Yoko
Published: May 2014

The phase transformation behavior of Ti-50Pd-5x (x =Zr, Hf, V, Nb, Ta, Cr, Mo, W) (at.%) alloys was studied by X-ray diffraction measurements from room temperature to 800 oC. In all the alloys, B19 martensite was observed at room temperature and it transformed to B2 phase upon heating. In addition, peaks corresponding to formation of (Ti, x)2Pd3 phase was seen for all the alloys. However, the temperature of formation of (Ti, x)2Pd3, interestingly, varied with respect to the elements group from the periodic table. Elements except from group IV (Zr and Hf) have been identified to accelerate the formation of (Ti, x)2Pd3 phase even at low temperatures (~400 oC).
Development of a Combined Method between MPS and FEM for Simulating Friction Stir Welding
Authors: Serizawa Hisashi , Shimazaki Junji , Miyasaka Fumikazu , Yoshikawa Gaku , Murakawa Hidekazu
Published: May 2014

In order to simulate the large deformation surrounding the rotational tool of friction stir welding (FSW) precisely, the moving particle semi-implicit (MPS) method was employed and the temperature distributions near the tool were obtained. Also, the temperature distributions in the whole model except for the area computed by MPS were calculated by the finite element method (FEM) and then the elastic-plastic analysis was conducted using the temperature distributions obtained by MPS and FEM. The inhomogeneous temperature distributions through the thickness near the joint line could be simulated and the maximum temperature distributions computed had a good agreement with the experiments. In addition, the longitudinal plastic strain distributions indicates that this plastic strain near the tool is not governed by only the temperature distributions and the influence of plastic flow should be taken into account.
Electrochemical Evaluation for Rust Preventive Properties of Rust Preventive Oils Coated on Fe-Cu-C Sintered Steel
Authors: Sunada Satoshi , Nunomura Norio , Hirata Sayaka , Nagase Naoki
Published: May 2014

Since Fe-Cu-C sintered steels are easily rusted, they are coated with rust preventive oils. High viscosity of those rust preventive oils decrease workability, and low viscosity deteriorates rust preventive performance. Therefore, it is necessary to develop new rust preventive oils with contradictory properties of low viscosity and superior rust prevention. However, precise methodology to evaluate rust prevention ability has not been established. In this study, we developed new technique to quantitatively evaluate rust prevention ability by measuring the open circuit potential through thin corrosive solution on Fe-Cu-C sintered steels coated with a rust preventive oils. As a result, the ability for rust prevention can be measured quantitatively, and it decreases slowly over time, with repeating destruction and restoration. Furthermore, it was found that the deteriorating processes of rust prevention ability for rust prevention oils are composed of three characteristics steps respectively. That is, in the first step the great open circuit potential changes from 0V to-0.3V with repetition were observed where the excellent rust prevention ability was kept, in the second step it decreases slowly from-0.1V to-0.4V with oscillation of the small potential changes where the gradual decrease of rust prevention ability was recognized and in the third step it decreases monotonously in the lower potential than-0.4V where the rust was observed because of the remarkable deteriorating of the rust prevention ability.
High-Temperature Shape Memory Alloys Based on Ti-Platinum Group Metals Compounds
Authors: Yamabe-Mitarai Yoko , Wadood Abdul , Arockiakumar Raju , Hara Toru , Takahashi Madoka , Takahashi Satoshi , Hosoda Hideki
Published: May 2014

The effect of alloying to TiPd and TiPt on phase transformation temperature, phase equilibria, and shape recovery were investigated for TiPt and TiPd base high-temperature shape memory alloys. Ru, Ir, Co and Zr were chosen for additional elements and Zr was found as the most effective element to improve shape recovery of TiPd and TiPt.
Influence of Strain Path on Work Hardening and Texture in an Austenitic Stainless Steel
Authors: Gärdsback Mattias , Chai Guo Cai , Hedström David , Persson Katarina
Published: May 2014

The effect of strain path on work hardening and texture for a super austenitic stainless steel was investigated using both experiments and modeling. Compression deformation tests by stepwise changing loading direction in two and three dimensions were performed on cubic specimens at room temperature. The results were compared to uniaxial compression with equal accumulative strain, up to 20%, and uniaxial tension with equal final strain, up to 10% elongation of the longest side. The textures in all samples were analyzed using pole figures from EBSD analysis. Because of the high stacking fault energy of this super austenitic stainless steel, the texture was dominated by <110>-fiber texture in the compressive direction for the uniaxial compression, <111>- and <100>-fiber texture in the tensile direction for the uniaxial tensile test, and a combination of all these for the cube deformation. The density of the texture was much weaker for samples where the loading direction altered, if samples with equal accumulated strain were compared. The cube deformation was also modeled using a crystal plasticity model. The crystal plasticity model consists of a representative volume element (RVE) containing crystal grains with random orientations. The Taylor assumption was used for homogenization between the macro-and subscale. The material parameters in the crystal plasticity model were determined by calibration of its macroscopic response to experimental data. The simulated textures correspond rather well to the experimental results, but the work hardening should be completed to take into account kinematic hardening.
The Role of Deformation Banding in Grain Refinement under ECAP
Authors: Kaibyshev Rustam , Malopheyev Sergey , Kulitskiy Vladislav , Gazizov Marat
Published: May 2014

The mechanism of grain refinement in an Al-5.4Mg-0.4Mn-0.2Sc-0.09Zr alloy subjected to equal-channel angular pressing (ECAP) at 300°C through route BC is considered. It was shown that the formation of geometrically necessary boundaries (GNB) aligned with a {111} plane at ε≤1 initiates the occurrence of continuous dynamic recrystallization (CDRX). Upon further strain the GNBs transform to low-to-moderate angle planar boundaries that produces lamellar structure. In the strain interval 2-4, 3D arrays of planar boundaries evolve due to inducing the formation of 2nd order and higher orders families of GNBs in new {111} planes. GNBs gradually convert to high-angle boundaries (HAB) with strain. A uniform recrystallized structure is produced at a true strain of ∼8. The role of slip concentration and shearing patterns in the formation of GNBs is discussed.
An Investigation of Hardness Homogeneity and Microstructure in Pure Titanium Processed by High Pressure Torsion
Authors: Wang Chuan Ting , Fox Alan G. , Langdon Terence
Published: May 2014

High-pressure torsion (HPT) was conducted on disks of commercial purity Ti under applied pressures of 3 and 6 GPa. Measurements of the Vickers microhardness showed improving hardness homogeneity with increasing numbers of HPT turns. Transmission electron microscopy demonstrated that a higher HPT pressure leads to a smaller grain size after straining and these grains contain a high dislocation density with arrays of twins. This is consistent with the higher hardness of the Ti samples processed by HPT under 6 GPa pressure.
Twinning-Induced Formation of Nanostructure in Commercial-Purity Titanium
Authors: Zherebtsov Sergey V. , Dyakonov Grigory , Klimova M. , Salishchev Gennady A.
Published: May 2014

In the present work the influence of various parameters on formation of nanoor ultrafine-grained structure in commercial-purity titanium during large deformation was quantified using TEM and EBSD. The beneficial effect of twinning on the kinetics of microstructure refinement in titanium was revealed. It was shown that deformation twinning (and therefore nanostructure formation) can be intensified via decrease in temperature, increase in the initial grain size and decrease in the impurities content. The minimum grain size at which twinning can still operate in commercial-purity titanium was determined to be ~1μm. It was shown that rolling to a thickness strain of 93% at-196°C resulted in the formation of a microstructure with a grain/subgrain size ~80 nm.
Thermal Joining with Zinc Based Solder – New Potentials for Structural Lightweight Design
Authors: Angerhausen Matthias , Geffers C. , Reisgen Uwe , Willms Konrad , Hof S. , Prenger F. , Deckert K.
Published: May 2014

The enhanced demands made to safety and comfort for vehicle occupants have, in recent years, resulted in a steady increase of the vehicle weight. The achievement of a good vehicle performance has been accompanied by the development of more effective combustion motors. However, all this entailed the increased out-put of detrimental exhaust fumes. More restrictive environmental requirements demand the future reduction of the vehicle weight. In order to follow those requirements, different lightweight concepts are currently being followed. The application of higher-strength steel materials allows the reduction of the vehicle weight with, at the same time, increase of the part strength. A further possibility is composite construction which, depending on local demands on the material, means the application of the proper material at the proper position in the vehicle. The highest importance is attached to the combination of steel and aluminium. The development of modern, digitally controlled arc processes has rendered the process-reliable reproducible joining of steel to aluminium possible. Within the framework of a publicly sponsored project, the joining of vehicle-relevant materials with different short-arc processes using low-melting zinc-based brazing solders is currently investigated.
Microstructural Evolution in Dissimilar Joint of Al Alloy and Cu during Ultrasonic Welding
Authors: Fujii Hiromichi T. , Goto Yuta , Sato Yutaka S. , Kokawa Hiroyuki
Published: May 2014

Dissimilar joints between 1050 Al alloy and Cu were prepared by ultrasonic spot welding technique to understand the joint characteristics. The joint strength was evaluated by tensile shear strength test. The joint strength increased with increasing joining energy and the joint produced with sufficiently high energy was fractured at the base metal region of Al alloy. The interface microstructure in Al alloy consists of severely deformed region due to ultrasonic vibration. In addition, the fine and equiaxed grains were observed near the joint interface in the specimens fractured at the base metal. These characteristics were significantly different from the microstructure in the bulk region of Al alloy. In contrast, the microstructure in Cu was hardly changed around the interface after ultrasonic welding. Additionally, thin intermetallic compound layer with the thickness of 40 nm was found to be formed at the joint interface in the specimens fractured at the base metal. Peak temperature during ultrasonic welding was found to be approximately 480 K at the interface, which was measured using embedded thermocouple.
Sources and Consequences of Residual Stresses due to Welding
Authors: Nitschke-Pagel Thomas , Dilger Klaus
Published: May 2014

A detrimental parameter which is always connected with welding processes is the distortion which may occur in welded components. The reduction of distortion is a very costly production factor and in complex constructions the disposal of the distortion might be very complicate or even impossible. On the other hand we know that every step which is done to increase the stiffness of a welded component in order to avoid distortion is connected with the possibility of the generation of higher tensile residual stresses.
Novel Micro-Welding of Silicon and Glass by Ultrashort Pulsed Laser
Authors: Okamoto Yasuhiro , Miyamoto Isamu , Vihinen Jorma , Okada Akira
Published: May 2014

The laser welding can provide flexible processing, and ultrashort pulsed laser with high pulse repetition rates enabled locally selective welding of monocrystalline silicon and glass with comparable processing performance to anodic bonding method. The 20ps laser pulse of 1060nm was absorbed at monocrystalline silicon through glass plate, and its surface temperature reached its boiling temperature. In addition, it was considered that the absorption of laser energy to glass was occurred, and the temperature of glass increased more than the forming temperature. Thus the convection of silicon and glass was caused by the recoil pressure of evaporation, which led to mild mixture of silicon and glass. This phenomenon produced anchor geometry at the interface between silicon and glass without gap generation. The number of laser shot in the laser spot had an influence on shearing strength of weld joint, and higher shearing strength of weld joint could be performed at proper number of laser shot in the laser spot.
Effect of Strain Rate on Tensile Properties of Miniature Size Specimens of Several Lead-Free Alloys
Authors: Shohji Ikuo , Toyama Yuichiro
Published: May 2014

The effect of strain rate on tensile properties of several lead-free solder was investigated using miniature size specimens. High-temperature lead-free solder which are Sn-Cu and Sn-Sb alloys were prepared. Moreover, low-Ag lead-free solder which are Sn-1Ag-0.7Cu (SAC107, mass%) based alloys were prepared. Sn-3Ag-0.5Cu (SAC305) was also prepared for comparison. Tensile strength is proportion to the logarithm of strain rate in all solder investigated. Although 0.1% proof stress decreases at high strain rate in high-temperature solder, it scarcely changes in low-Ag solder. Elongation somewhat increases with increasing strain rate in high-temperature solder. It increases with increasing strain rate in low-Ag solder although it is lower than that of SAC305. Chisel point fracture mainly occurred except Sn-13Sb. In Sn-13Sb, brittle fracture occurred and thus elongation was lower than those of other solder. Sn-8.5Sb and Sn-1Ag-0.7Cu-1Bi-0.2In show mechanical properties similar to SAC305.
Recrystallization Microstructure and Texture of Highly Strained Commercial Purity Aluminium Alloy
Authors: Wu Gui Lin
Published: May 2014

The microstructural and textural evolutions during annealing of a highly strained (ε=4.0) commercial purity aluminium (AA1200) were followed by electron backscatter diffraction (EBSD). Boundary spacings were analyzed for crystallites of different crystallographic orientations. It was found that initially during the annealing the microstructural evolution is dominated by recovery of the highly strained microstructure, while later the microstructure consists of identifiable grains nucleating and growing at the expense of deformed and recovered matrix. No much texture change occursduring early stages of annealing, whereas a cube texture evolves and dominates after complete recrystallization.
Plasma Diagnostics of Arc during MIG Welding of Aluminum
Authors: Tanaka Manabu
Published: May 2014

In this study, distributions of temperature and metal vapor during MIG welding of aluminum are obtained. Since a droplet forms and detaches at a tip of wire, and pass through the arc plasma during MIG welding, dynamic plasma diagnostics are demanded. This study aims to develop method for measuring dynamical variation of two-dimensional distribution of temperature and metal vapor concentration in the arc through optical measurement and to analyze behavior of the metal vapor in MIG welding. As the results, in MIG welding of aluminum, the arc plasma has double structure consisting of high temperature region apart from the arc axis and low temperature region near the arc axis due to influence of the aluminum vapor. Furthermore, the low temperature region near the arc axis occurs because the arc plasma is cooled especially through the intensive radiation loss caused by high concentration of the metal vapor.
Thermal Recovery of Plastic Deformation in Dissimilar Metal Weld
Authors: Qiao Dong Xiao , Yu Xing Hua , Zhang Wei , Yu Paul Crooker , David Stan , Feng Zhi Li
Published: May 2014

Stainless steel has been widely used in challenging environments typical to nuclear power plant structures, due its excellent corrosion resistance. Nickel filler metals containing high chromium concentration, including Alloy 82/182, are used for joining stainless steel to carbon steel components to achieve similar high resistance to stress corrosion cracking. However, the joint usually experience weld metal stress corrosion cracking (SCC), which affects the safety and structural integrity of light water nuclear reactor systems. A primary driving force for SCC is the high tensile residual stress in these welds. Due to large dimension of pressure vessel and limitations in the field, non-destructive residual stress measurement is difficult. As a result, finite element modeling has been the de facto method to evaluate the weld residual stresses. Recent studies on this subject from researchers worldwide report different residual stress value in the weldments [5]. The discrepancy is due to the fact that most of investigations ignore or underestimate the thermal recovery in the heat-affect zone or reheated region in the weld. In the current study, the effect of heat treatment on thermal recovery and microhardness is investigated for materials used in dissimilar metal joint.
It is found that high equivalent plastic strains are predominately accumulated in the buttering layer, the root pass, and the heat affected zone, which experience multiple welding thermal cycles. The final cap passes, experiencing only one or two welding thermal cycles, exhibit less plastic strain accumulation. Moreover, the experimental residual plastic strains are compared with those predicted using an existing weld thermo-mechanical model with two different strain hardening rules. The importance of considering the dynamic strain hardening recovery due to high temperature exposure in welding is discussed for the accurate simulation of weld residual stresses and plastic strains. Finally, the experimental result reveals that the typical post-buttering heat treatment for residual stress relief may not be adequate to completely eliminate the residual plastic strains in the buttering layer.
Surface Property Enhancement of UNS N07718 and G41400 by Ultrasonic Impact Treatment
Authors: Singh Virendra , Marya Manuel , Roy Indranil , Mathews Cijo , Spinner Dan , Gopalakrishnana Mv
Published: May 2014

Ultrasonic impact treatment is a relatively new surface modification process that may be potentially applied to impart compressive residual stresses onto oilfield parts experiencing wear, fatigue, and possibly environmentally-assisted cracking. Through severe plastic deformation, ultrasonic impact treatment is herein investigated to surface harden two oilfield alloys, UNS N07718, a premium alloy with satisfactory oilfield performance but occasionally lacking surface hardness and abrasive wear resistance, and UNS G41400, a comparatively low-cost alloy restricted by its corrosion fatigue limit in oilfield rotating equipment. For comparison purposes, the two studied alloys were ultrasonic impact treated under identical conditions and carefully selected to exhibit similar yield strengths (900 MPa). Results from microstructural examinations, micro-hardness indentations, and residual stress measurements all indicate that ultrasonically treated surfaces exhibit superior properties that create opportunities for implementing this new surface modification process in selected oilfield applications.
Influence of Cold Rolling Reduction and Cross Rolling on Recrystallization Texture Formation in Electro Deposited Pure Iron with a Sharp and Homogeneous <111>//ND Fiber
Authors: Yoshinaga Naoki , Vanderschueren Dirk , Kestens Leo A.I. , Ushioda Kohsaku , Sugiura Natsuko
Published: May 2014

The cold rolling and annealing texture formation has been investigated in electro deposited pure iron which has an extremely sharp and isotropic <111>//ND fiber. Regardless of cold rolling reduction, {111}<112> intensified texture is formed after cold rolling. Similar texture remains after recrystallization in 65% cold rolled material while {111}<110> type texture forms in 80% and 90% cold rolled ones. The recrystallized grains at the stage of 5% recrystallization have {111}<112> orientation in 65% cold rolled sheet, whereas {111}<110> is observed in 80% cold rolled one. From this aspect, it is considered that the nucleation orientation plays an important role in the recrystallization texture formation. In the meanwhile, the growth of the recrystallized nuclei is also supposed to affect the recrystallization texture formation. The nuclei with {111}<112> orientation in lightly cold rolled sheet are easier to consume the deformed matrix than they do in heavily cold rolled sheets because their frequency to encounter a deformed grain with nearly the same orientation is much smaller in lightly cold rolled specimen, which can result in a large mobility for growth. Cross cold rolling makes cold rolling texture rather homogeneous <111>//ND fiber, which gives rise to an almost homogeneous <111>//ND fiber after annealing.