bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microstructure Control Using Precipitate Phases for the Development of Heat Resistant Fe3Al-based Alloys
Authors: Kobayashi Satoru , Zaefferer Stefan 
Published: June 2019

AbstractA thermomechanical process (TMP) was performed to create a fine grained and recovered structure with densely formed fine particles in Fe3Al-Cr-Mo-C alloys. The TMP consists of two parts; the first part is to obtain fine recrystallised grains using coarse particles and the second to produce deformed/recovered structure using fine particles. It was found that k-Fe3AlC (E21) carbide phase tends to precipitate coarsely, which is effective to refine grain size in the first process. In a special composition range, the k carbide phase is thermo- dynamically stable in the Fe3Al matrix only at higher temperatures and fine M(Mo,Cr,Fe)2C (B81) carbide phase precipitates at lower temperatures. This fine M2C particles stabilize recovered structure by inhibiting the migration of subboundaries in the second process. This result suggests that if the fine particle density remains high, recovered structure can be maintained at 700°C.
Precipitation-Induced Nano-Twinning
Authors: Fischer Franz Dieter , Appel Fritz , Clemens Helmut 
Published: June 2019

Abstractγ(TiAl) alloys containing Ti3AlC perovskite precipitates show overlapping planar faults, which can apparently rearrange into embryonic twins and subsequently grow into large twins. An electron-microscopical study is introduced and followed by a micromechanical modelling of the fault and twin development process. The thickness and length of the embryonic twins can be predicted with the developed model.
L10 Ordered Intermetallics for Ultrahigh Density Magnetic Recording Media: Phase Formation and the Role of Alloy Chemistry and Composition
Authors: Berry David C. , Barmak Katayun 
Published: June 2019

AbstractIn this paper we provide a summary review of our research regarding the effect of composition on the A1 to L10 transformation in binary FePt with compositions in the range of 39.3 to 55.3 at.% Pt and ternary FeCuPt alloys with Cu additions in the range of 1.0 to 19.4 at.%. These binary and ternary alloy films have been studied using non-isothermal differential scanning calorimetry (DSC) combined with the calculation of TTT diagrams generated via experimentally validated Johnson-Mehl-Avrami-Kolmogorov (JMAK) analysis. Composition is found to play a significant role in the transformation kinetics in both FePt and FeCuPt. However, when comparing equivalent FePt and FeCuPt alloys, the addition of Cu has no significant effect. TTT diagrams show that as little as a 90 °C increase in peak temperature from the DSC measurements can result in a >300× increase in the time required for full transformation using isothermal anneals. Our results on the effect of Cu additions are compared with those reported in the literature.
Defect Control and Defect Engineering of Transition-metal Silicides
Authors: Inui Haruyuki , Tanaka Katsushi , Kishida Kyosuke 
Published: June 2019

AbstractThe microstructure, defect structure and thermoelectric properties of two different semiconducting transition-metal silicides, ReSi1.75 and Ru2Si3 upon alloying with a substitutional element with a valence electron number different from that of the constituent metal have been investigated in order to see if the crystal and defect structures of these silicides and thereby their physical properties can be controlled through defect engineering according to the valence electron counting rule. The Si vacancy concentration and its arrangement can be successfully controlled in ReSi1.75 while the relative magnitude of the metal and silicon subcell dimensions in the chimney-ladder structures can be successfully controlled in Ru2Si3. As a result, the improvement in the thermoelectric properties and the p- to n-type conduction transition are successfully achieved respectively for these semiconducting transition-metal silicides.
Solid-State Synthesis of Magnesium Base Thermoelectric Alloys via Bulk Mechanical Alloying
Authors: Aizawa Tatsuhiko , Song Renbo 
Published: June 2019

AbstractMagnesium binary and ternary alloy systems have been popular as a thermoelectric light-weight alloy to be working in the medium temperature range. The solid-state reactivity via the bulk mechanical alloying is applied to yield these types of alloys. The diffusion-controlled solid-state synthesis is first stated as a process to yield a binary compound, Mg2X (X = Ge, Sn and Pb). This processing is further applied to directly synthesize several ternary thermoelectric alloys Mg2Si1-xGex, Mg2Si1-ySny and Mg2Sn1-zPbz for 0.0 < x, y, z < 1.0 and to evaluate their thermoelectric properties. Hot pressing is used to make full-dense billets and samples for thermoelectric measurement. The effect of germanium and tin contents on their Seebeck coefficient and band-gap is investigated to describe the p-n transition behavior and to understand the change of electric structure with solid solution formation.
The Evolution of Prior-BCC Grain Boundary Cracking During In-situ Creep Deformation of a Ti-15Al-33Nb(at%) Alloy
Authors: Cowen Christopher J. , Boehlert Carl J. 
Published: June 2019

AbstractIn-situ tensile-creep experiments were performed on a Ti-15Al-33Nb(at%) alloy using a specialized tensile stage placed within the vacuum chamber of a Camscan 44 FE scanning electron microscope (SEM). The creep damage evolution on the sample surface was chronicled through backscattered electron (BSE) imaging as a function of stress, time, and creep displacement at 650°C. The experiments revealed that the prior-BCC grain boundaries were the locus of damage accumulation during creep and significant grain boundary cracking was observed. The grain boundary cracking was verified to occur within the bulk of the material through post-mortem analysis.
Phase Equilibria among γ-Fe, γ-Fe and Fe2Mo Phases and Stability of the Laves Phase in Fe-Mo-Ni Ternary System at Elevated Temperatures
Authors: Ishikawa Shigehiro , Matsuo Takashi , Takeyama Masao 
Published: June 2019

AbstractPhase equilibria among the bcc Fe(α), fcc Fe(γ) and Fe2Mo(λ)_phases in Fe-Mo-Ni ternary system, particularly paying attention to the existence of the γ+λ two-phase region, have been examined at elevated temperatures below Tc (1200 K), the peritectoid reaction temperature in Fe-Mo binary system: λ?α+Fe7Mo6 (μ). At 1173 K the α+γ+μ three-phase coexisting region exists near the Fe-Mo binary edge and no λ phase region was identified. At 1073 K the λ phase in equilibrium with α and γ phases exists, although the composition homogeneity region of the ternary λ phase was limited to its binary edge toward the equi-nickel concentration direction up to about 3at % Ni. Instead, large two-phase region of γ+μ was extended along the same direction up to 20 at% Ni. The γ+λ two-phase region appears below Tc through a transition peritectoid reaction: α+μ¨γ+λ. The γ phase in equilibrium with λ phase is stable only at elevated temperatures, and it transforms martensitically to α phase during cooling. The addition of Ni stabilizes γ and μ phases against α and λ phases, thereby decreasing the relative stability of the λ phase.
UFG to NC FePd by Combined Reaction Transformation Mode of Severely Plastically Deformed Disordered FePd
Authors: Sokalski Vincent , Kulovits Andreas , Wiezorek Jorg 
Published: June 2019

AbstractNumerous studies have shown that equiaxed ultra fine grained FePd alloys can be produced by phase transformation of heavily deformed austenitic FePd via the combined reaction mode. As the magnetic properties can be improved by suppression of the polytwinned micro-constituent formed by the conventional ordering mode it appears reasonable to speculate that further grain refinement might lead to further enhancement. In order to reduce the grain size in bulk intermetallic alloys severely plastically deformed austenitic FePd has been phase transformed in this study. Equal channel angular pressing (ECAP) has been used to deform disordered FePd. The microstructure and property evolution during the deformation process and post-deformation annealing have been studied using SEM, TEM and hardness and magnetization curve measurements. The observations are compared to known results from use of other deformation processing routes, such as cold rolling.
Microstructure and Mechanical Properties of Dual Two-Phase Intermetallic Alloys Composed of GCP Ni3Al and Ni3V Phases containing Nb
Authors: Soga Wataru , Kaneno Yasuyuki , Takasugi Takayuki 
Published: June 2019

AbstractDual multi-phase intermetallic alloys composed of Ni3X (X: Al and V) containing Nb were developed, on the basis of the Ni3Al-Ni3Nb-Ni3V pseudo-ternary alloy system. The dual multi-phase intermetallic alloys were characterized by scanning electron and transmission electron microscopies. High-temperature compression and tension tests, and compression creep test were conducted. It was found that the dual multi-phase intermetallic alloys show high yield and tensile strength with good temperature retention, accompanied with reasonable tensile ductility. The compression creep test conducted at high temperature showed lower creep rate in the dual multi-phase intermetallic alloys than in conventional Ni-base superalloys. The obtained results are superior to the dual multi-phase intermetallic alloys containing Ti.
The Broadening of Crystallographic Orientation Distribution in Crept Ni-base Superalloys
Authors: Inoue Toru , Tanaka Katsushi , Adachi Hiroki , Kishida Kyosuke , Inui Haruyuki 
Published: June 2019

AbstractThe crystallographic orientation distribution, and its change accompanied with tilting γ/γ boundaries in Ni-based single crystal superalloys have been investigated by a theoretical elastic-plastic calculation, X-ray diffractometry and SEM-EBSD analysis. The distribution of the crystallographic orientation has significantly broadened by creep deformations. The broadening can be explained by an unbalance of the amount of creep dislocations of each slip system, which agrees with the result of elastic-plastic calculations. Creep strain of superalloys crept at a condition forming the raft structure can be estimated by the measurement of the width of rocking curve of a diffraction peak.
Effect of Heat Treatment on the Ductility of Ni(γ)/Ni3Al(γ') Two-phase Alloy Foils
Authors: Nakamura Motonori , Demura Masahiko , Xu Ya , Hirano Toshiyuki 
Published: June 2019

AbstractThe microstructures and room-temperature tensile properties were examined in the 95% cold-rolled and subsequently heat-treated foils of the boron-free Ni(γ)/Ni3Al(γ') two-phase (Ni-18at.%Al) alloys. The electron backscatter diffraction measurements revealed that the recrystallization started at 873 K/0.5 h and that it completed at 1273 K/0.5 h. While the foils showed no tensile elongation in the cold-rolled state, they became ductile after the heat-treatments at 873 K and above. The tensile elongation increased with the increasing heat-treatment temperature: it reached to 14% at 1273 K/0.5 h. The tensile elongation and the fracture strength were high, compared to those in the γ' single-phase foils. The fracture mode was intergranular, and it changed to a mix of intergranular and transgranular in the foils heat-treated at 1273 K/0.5 h, where the area fraction of crack resistant boundaries such as °1, °3 and °9 was high, 0.63. The high ductility was ascribed to the existence of the ductile γ matrix and to the high fraction of crack-resistant boundaries.
Dynamics of Ultrafast Laser Induced Damage in Single Crystal Ni-based Superalloy During Machining
Authors: McDonald Joel P. , Ma Shuwei , Nees John A. , Pollock Tresa M. , Yalisove Steven M. 
Published: June 2019

AbstractPump-probe imaging of femtosecond pulsed laser ablation was performed to investigate the mechanical shock induced on an intermetallic superalloy CMSX-4 during femtosecond laser machining. Time resolved shadowgraphic images were collected of the shock wave produced in the air above the target following laser exposure (0-10.3 nanoseconds). The dimensions of the shock wave were measured as a function of delay time and laser fluence (1.27 J/cm2 - 62.8 J/cm2). Time-resolved shadowgraphic images of the ablation event will be presented, and the corresponding damage morphology as a function of incident laser fluence will be discussed.
Microstructure and Mechanical Properties of Multi-Phase Intermetallic Alloys Composed of GCP Ni3X (X:Si, Ti and Nb) Phases
Authors: Fujita Masayoshi , Kaneno Yasuyuki , Takasugi Takayuki 
Published: June 2019

AbstractUsing alloys whose initial microstructures are composed of Ni3Si(L12), Ni3Si(L12)+Ni3Ti(D024) and Ni3Si(L12)+Ni3Nb(D0a), aging phenomenon and the associated high-temperature tensile property were investigated. It was shown by micro hardness measurement that age hardening behavior due to the precipitation of the Ni3Ti(D024) phase occurs in all alloys at temperatures above 823K. It was however shown by tensile test that the precipitated Ni3Ti(D024) phase is not so much effective in improving the mechanical properties of alloys whose initial microstructures are composed of Ni3Si(L12)+Ni3Nb(D0a) or Ni3Si(L12)+Ni3Ti (D024). In alloys whose initial microstructures are composed of Ni3Si(L12)+Ni3Nb (D0a), a good combination of tensile strength and tensile elongation was found over a wide of test temperature whether or not they contain the precipitated Ni3Ti(D024) phase.
Effect of processing and Microalloying Elements on the Thermal Stability of Cr-Cr3Si and NiAl-Mo eutectic alloys
Authors: Gali A. , Bei H. , George E. P. 
Published: June 2019

AbstractThe thermal stability of multiphase intermetallics at temperatures to 1400°C was investigated by studying two model eutectic systems: Cr-Cr3Si having a lamellar microstructure and NiAl-Mo having a fibrous microstructure. In drop cast Cr-Cr3Si, coarsening was found to be interface controlled. The coarsening rate could be reduced by microalloying with Ce and Re, two elements which were chosen because they were expected to segregate to the Cr-Cr3Si interfaces and decrease their energies. Similarly, directional solidification, which is also expected to lower the Cr-Cr3Si interfacial energy, was found to dramatically decrease the coarsening rate. In the case of NiAl-Mo, coarsening was found to occur by fault migration and annihilation. Microalloying with B was found to significantly decrease the coarsening rate. The fiber density in the B-doped alloy was smaller than in the undoped alloy, suggesting that B affects the coarsening rate by lowering the fault density.
Crystal Structures and Thermoelectric Properties of Ru1-xRexSiy Chimney-Ladder Compounds
Authors: Ishida Akira , Okamoto Norihiko L. , Kishida Kyosuke , Tanaka Katsushi , Inui Haruyuki 
Published: June 2019

AbstractThe phase relationship of Re-alloyed Ru2Si3 and the variations of the crystal structures and thermoelectric properties of the Ru1-xRexSiy chimney-ladder phases have been studied as a function of the Re concentration. The Ru1-xRexSiy chimney-ladder phases are formed in a wide compositional range. Compositional formula of the chimney-ladder phases are determined to be Ru1-xRexSi1.5386+0.1783x (0.14 ≤ x ≤ 0.76), which are systematically deviated from the idealized composition conforming the valence electron counting rule: VEC=14. Measurements of thermoelectric properties of single crystals with different compositions reveals that the chimney-ladder phases exhibit n-type semiconducting behavior at low Re concentrations and p-type semiconducting behavior at high Re concentrations. These results suggests that the VEC=14 rule can be used for predicting the semiconducting behavior of the chimney-ladder phases through the adjustment of VEC values by substituting elements, producing p-type semiconductors for VEC<14 and n-type for VEC>14, with the carrier concentration related to the deviation from VEC=14.
Thermoelectric and Electrical Properties of InSb Thin Films Prepared by Metalorganic Chemical Vapor Deposition
Authors: Matsumoto Masashi , Yamazaki Jun , Yamaguchi Shigeo 
Published: June 2019

AbstractWe studied the thermoelectric and electrical properties of InSb thin films prepared by metalorganic chemical vapor deposition. The thermoelectric properties were evaluated using power factor (Pf =α2/Ï), which is an important criterion, and a value of 10-3 W/mK2 is a standard for practical use. Maximum value of Pf was 2.4×10-3W/mK2 at 600K for 1-μm-thick InSb, 3.4×10-3W/mK2 at 600K for 3-μm-thick InSb, and 5.8×10-3W/mK2 at 600K for 5-μm-thick InSb. On the other hand, the maximum Pf of bulk-InSb was 5.4×10-3W/mK2 at 600K.
Lanthanide Based Ternary Intermetallics as Advanced Thermoelectric Materials
Authors: Kurosaki Ken , Sekimoto Takeyuki , Kawano Kenta , Muta Hiroaki , Yamanaka Shinsuke 
Published: June 2019

AbstractPolycrystalline ingots of the lanthanide based ternary intermetallics: LaNiSb, GdNiSb, ErNiSb and ErPdSb were prepared and characterized. The thermoelectric properties of ErNiSb and ErPdSb were measured at high temperatures. We succeeded in preparing the single phase ingots of ErNiSb and ErPdSb, while the ingots of LaNiSb and GdNiSb contain appreciable quantities of the impurity phases. ErNiSb and ErPdSb crystallize the MgAgAs-type structure (half-Heusler structure). ErNiSb and ErPdSb indicate positive values of the Seebeck coefficient. The values at room temperature are 36 and 240 micro VK-1 for ErNiSb and ErPdSb, respectively. The electrical resistivity of ErNiSb and ErPdSb decreases with temperature, indicating semiconductor-like behavior. ErPdSb exhibits a relatively large power factor 1.5x10-3 Wm-1K-2 at around 700 K, which is approximately two times larger than that of ErNiSb.
Investigation of AuNi5 Films Deposited by Pulsed Laser Deposition for RF MEMS Switch Contacts
Authors: Farghal Noha , Ghannam Moustafa Yehia , Shaarawi Amr M. , El Samman Hussein , Soussan Philippe , Baert Kris 
Published: June 2019

AbstractIn this work, the material properties of AuNi5 films prepared by Pulsed Laser Deposition (PLD) to be used as contact materials in RF MEMS switches are investigated. PLD is used because it provides good wide range thickness control (few nanometers to tens of microns) while preserving ablation target stoichiometry. Films with thickness in the range 50 - 450 nm were deposited at Laser energy density (fluence) in the range 0.55 - 1.38 J.cm-2 on silicon substrates at room temperature. An aperture was placed between the plume and the substrate to filter out large particulates. The presence of the aperture reduced surface roughness from 8.5 nm to 4.3 nm as determined by optical profilometry. In addition, the presence of the aperture during deposition has been found to affect film stoichiometry. The latter was evaluated using X-ray Fluorescence and the Nickel content has been found to vary in the range 1.1 - 9.5%. Only films deposited with the aperture removed maintain target stoichiometry (5.2% Ni). Hence, it is believed that the presence of the aperture causes non-congruent transfer. The Nickel content within the range under investigation has practically no effect on film morphology or hardness. Laser fluence, however, has been found to be the dominant factor determining film properties. Finally, 100 µm wide AuNi5 strips 290 nm and 130 nm thick deposited at room temperature have been successfully formed on silicon wafers by lift-off photolithography.
Crystal Growth of β-FeSi2 Thin Film on (100), (110) and (111) Plane of Si and Yittria-stabilized Zirconia Substrates
Authors: Akiyama Kensuke , Kaneko Satoru , Kiguchi Takanori , Suemasu Takashi , Kimura Takeshi , Funakubo Hiroshi 
Published: June 2019

AbstractIron silicide thin films were prepared on silicon (Si) and yittria-stabilized zirconia (YSZ) substrates using RF magnetron sputtering and evaporation methods. Epitaxial b-FeSi2 thin films were grown on (100) and (111) planes of Si and YSZ substrates, while noncrystallized films were deposited on (110) plane of both Si and YSZ substrates. The epitaxial relationships between the b-FeSi2 and YSZ were the same as those between b-FeSi2 and Si, in the case of (100) and (111) planes. It is possible that epitaxial b-FeSi2 film can be grown when substrates and b-FeSi2 surfaces consist of either a single element or only cations, while the crystalline film was not shown when either substrate or b-FeSi2 surface consists of a mixture of anions and cations or iron and silicon.
Evolution of Antiphase Domains and γ Lamellae in Ti-39at%Al Single Crystals
Authors: Koizumi Yuichiro , Iwamoto Kazuki , Tanaka Takayuki , Minamino Yoritoshi , Tsuji Nobuhiro 
Published: June 2019

AbstractWe studied antiphase domain (APD) growth and lamellar structure formation during isothermal annealing of Ti-39at%Al single crystals at α2+γ dual phase temperature after quenching from α single phase state, intending to obtain a APD/lamellae mixed microstructure and to examine whether such a microstructure provides a strength higher than that obtained only by refining lamellar structure. The effect of plastic deformation prior to the annealing was also examined expecting a acceleration of γ lamellae formation through a preferential nucleation of γ-plates at dislocations. The lower was the annealing temperature, the smaller both the APD size and the lamellar spacing at the moment of a homogeneous lamellar structure formation tended to be, although naturally both the APD growth and the γ lamellae formation were slower. However, the APD size in the homogeneous lamellar structure was no smaller than 400 nm. A structure with finer APDs and finer lamellar structure was obtained by deforming the crystal before annealing since the lamellar structure formation was accelerated and the time for APD growth before the lamellar structure formation was shortened. For instance, a structure with an average lamellar spacing of 88 nm and an average APD size of 214 nm was obtained by deforming the crystals to 10 % plastic strain and subsequently annealing at 1073 K for 1×104 s, while no γ plate was obtained only by such an annealing without deformation.
Nano-Scale Design of TiAl Alloys Based on beta-Phase Decomposition
Authors: Appel Fritz , Oehring Michael , Paul Jonathan 
Published: June 2019

AbstractPhase decomposition and ordering reactions in beta-phase containing TiAl alloys were utilized to establish a novel, previously unreported, type of laminate microstructure. The characteristic constituent of this microstructure are laths with a nanometer-scale substructure that are comprised of several stable and metastable phases. The constitution and microstructure of this novel type of alloy has been assessed by high-resolution transmission electron microscopy. Finally brief mention is made of the mechanical properties of the material.