Multiple In_0.18Ga_0.82N (4 nm)/GaN (40 nm) quantum well (QW) layers in a green laser diode were observed by high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) and conventional transmission electron microscopy. HAADF-STEM provided undoubted evidence that V defects in the multiple QW have the thin six-walled structure with InGaN/GaN {10\\bar11} layers. The detailed structure of the observed V defects is discussed on the basis of the formation mechanism of V defects which was proposed taking into account the growth kinetics of the GaN crystal and a masking effect of In atoms segregated around the threading dislocation (Shiojiri et al. J. Appl. Phys. 99, (2006) 073505).

Microstructure, chemical and phase composition of the hard layer formed on the Ti-6Al-4V alloy after duplex surface treatment were investigated by light microscopy (LM), X-ray diffraction (XRD) and analytical scanning, transmission and scanning transmission electron microscopy (SEM, TEM, STEM), electron diffraction and focused ion beam (FIB). Advanced electron microscopy techniques used for unambiguous identification of phases present in the surface multilayer are critically discussed. The relationship between multilayer micro/nanostructure containing several phases from the Ni-Ti-P-Al system and improved mechanical and tribological properties is established.

Oriented and densely dispersed L1₀-FePtCu nanoparticles have been directly synthesized by co-evaporation of Fe, Pt and Cu using rf-magnetron sputtering onto NaCl substrate kept at 563–613 K without any post-deposition annealing. Formation of the L1₀-type structure in the specimens fabricated as low a substrate temperature as 563 K (Fe₄₀Pt₅₀Cu₁₀) was confirmed by electron microscopy and electron diffraction, while the coercivity measured at room temperature was very low and the intensity of the superlattice reflections was quite weak. The atomic ordering was promoted in the specimen fabricated at 613 K with a composition of Fe₃₇Pt₅₂Cu₁₁, resulted in a higher coercivity exceeding 1 kOe at room temperature as well as appearance of clear superlattice reflections. In addition to the evolution of atomic ordering, ⟨100⟩ oriented growth was enhanced as the substrate temperature increased. Particle size dependence of long-range order (LRO) is considered to be responsible for the decrease of coercivity with particle size reduction as well as thermal fluctuation of magnetization. High coercivity was obtained for specimens with Cu concentration near 10 at% under the present sputtering condition. The LRO in the FePtCu ternary phase is considered to sensitively depend on the alloy concentration.

The effect of increased Ta and Nb additions on the structure of high energy ball milled Ti alloys was studied using X-ray diffraction and high resolution TEM. Ball milled powders were consolidated using ultra high pressure from 4–7 GPa at temperatures of 650–700°C. The microstructure of the compacts consisted of ultra fine grains in the range of 20 nm of α and β phases. Micro-hardness measurements showed very high hardness of ball milled and compacted powders close to 7 GPa (slightly decreasing with the increase of alloying additions) and a decrease in the Young’s modulus with the increase of Nb and Ta content i.e. the amount of β phase.

The surface treatment with Tb-vapor sorption improves the magnetic properties of small-sized magnets. Microstructure of the Tb-treated magnets was investigated by transmission electron microscopy (TEM). By applying the Tb-treatment, the diffusion of Tb through grain boundaries occurred even inside the magnets, and then a thin and continuous wetting-layer phase was formed at the boundaries between the Nd₂Fe₁₄B grains. The results suggest that the formation of the thin and continuous wetting-layer phase leads to the improvement in magnetic properties.

In equilibrium binary W-C system, mono-carbide WC is acknowledged as the stable phase under presence of excess free carbon up to temperature 2700°C whereas sub-carbide W₂C would form between 1250°C and 2700°C under the carbon-deficiency condition. In unique setup of solar furnace at PROMES-CNRS in Odeillo (France), temperature of specimen is raised from the ambient temperature to target temperature up to 2000°C within fractions of a second. In the recent experimental attempts of W₂C phase synthesis using this unique experimental facility starting from compacted pellet consisted of graphite and tungsten powders at ratios smaller than 0.50, we detected growth of nano-meter size WC whisker at the top surface directly exposed to the concentrated solar beam. The presence of WC was confirmed also by X-ray diffraction (XRD) of the top surface but, when the specimen as a whole was subjected to powder XRD analysis, WC became indiscernible being masked by principal W₂C phase. Mechanism of formation of the detected WC nano-whisker over sub-stoichiometric C/W pellet during ultra-fast heating by concentrated solar beam is discussed.

Phase transformation behaviors of the austenitic 301 stainless steel was studied under Fe⁺, Ti⁺ and Ar⁺ ions implantation at room temperature with 100, 200 and 300 keV up to fluence of 1×10²¹ ions/m² and the microstructures were observed by means of transmission electron microscopy (TEM). The plane and cross-sectional observations of the implanted specimen showed that the induced-phases due to implantation from the γ matrix phase were identified as α′ martensite phases with the orientation relationship of (1\\bar10)_α||(11\\bar1)_γ and [111]_α||[011]_γ close to the Kurdjumov–Sachs (K–S). The ion implantation induced phases nucleated near the surface region and the depth position of the nucleation changed depending on the ion accelerating energy and ion species. It was also found that the induced marten sites phases nucleate under the influence of the stress distribution, which is introduced due to the concentration of implanted ions, especially due to the stress gradient caused by the corresponding concentration gradient.

The microstructure in the as received condition and after long-term creep exposure (up to about 57000 h at 600 and 650°C of the martensitic 9–12% chromium steels (P92, P91, E911, CB6) developed for advanced ultra supercritical coal-fired power plants has been investigated. Using analytical TEM statistical quantitative analyses were undertaken to determine the micro- and nanoscale structure parameters (dislocation density within the subgrains, the width of the martensite laths/subgrains and the particles parameters). Results of the TEM analyses reveal significant influence of a microstructure after initial heat treatment on the creep strength.

Mechanisms responsible for the contrast between differently doped areas in semiconductors, which is observed in electron micrographs, is discussed as regards the key factors determining the sign and magnitude of the contrast. Experimental data obtained by means of the scanning electron microscope (SEM), scanning low energy electron microscope and photoelectron emission microscope are reviewed together with hints following from them for compilation of a model of the contrast mechanism.

New type of detection system has been designed and tested in the Scanning Electron Microscope. Backscattered electrons (BSE) at low energies of electron impact are collected by an annular detector above the specimen, consisting of eight concentric ring-shaped collectors arranged around the optical axis so that polar angles of the initial velocity vectors of electrons can be distinguished. Backscattering of electrons, in particular around and below 1 keV of impact energy, provides rich information content that even enhances toward higher angles with respect to the surface normal. Slow, high-angle BSE are normally not detected with standard detectors. The cathode lens principle was used to secure high lateral resolution, high collection efficiency and large amplification of the detector at low energies. Prospective applications include the grain orientation contrast, contrast between amorphous and crystallinic phases, etc.

The cathode lens (CL) mode of the SEM, employing sample as a cathode of the beam-decelerating electrostatic lens, enables one to preserve the image resolution down to lowest electron energies and in the same time secures an excellent collection efficiency of signal species. In the range of tens and units of eV, new image contrasts become available, based on the quantum mechanical character of scattering and the electron wavelength comparable with inter-atomic distances. However, already in the low keV and hundreds of eV ranges the CL mode has proven itself very efficient in many materials science applications, overcoming some weak points the conventional SEM modes suffer from. Selected material structures are presented as demonstration examples.

An application of scanning electron microscopy (SEM) electron beam induced current (EBIC) technique for measurement of layer or strip resistance and sheet (surface) resistance is described. In the method a high electron beam current is used. In this range the EBIC (I_EBIC) depends on the overall resistance of EBIC circuit. It includes a specimen resistance as well, as generated carriers create I_EBIC current that flows along the measured layer or strip to an ohmic contact. A shift of the electron beam towards the ohmic contact on the layer (or on the strip) changes resistance of layer (or strip) between the e-beam placement and the contact. The change of resistance that results is compensated using a changeable resistance (e.g. a decade resistance box). Provided constant I_EBIC despite the e-beam movement brings values of the resistance and the sheet resistance for the investigated layer or strip. Spatial distributions of resistance and local inhomogeneities can be also revealed. The method was used for the characterization of lateral confinements in semiconductor laser heterostructures manufactured by Molecular Beam Epitaxy and wet chemical or reactive ion etching. The method can be used for very thin layers and is expected to be applicable for small-size objects as nanostructures.

Precipitation sequence of the Mg-8.3 mass%Gd-3.7 mass%Y-0.76 mass%Zr alloy at 423 K was investigated by high resolution transmission electron microscopy (HRTEM). After heat treatment of the solution and quenching, the aging treatment was performed for 1024 h at 423 K. In the specimen aged at 423 K for 64 h monolayers on the {1\\bar100}_Mg planes composed of Gd and Y atoms, β″ phase with D0₁₉ structure and β′ phase with base centered orthorhombic structure already co-existed. The β″ phase is likely created via growth of monolayers composed of Gd and Y atoms on {1\\bar100}_Mg planes. Co-existence of the monolayers on {1\\bar100}_Mg planes and β″ and β′ phases continued up to 1024 h of aging at 423 K when the specimen reaches its maximum hardness. Both the β″ and β′ phases grew along the ⟨11\\bar20⟩_Mg direction, while along the ⟨1\\bar100⟩_Mg direction only grow of the β′ phase has been observed.

A hypereutectic Al-Si-Cu-Mg alloy billet was fabricated by a semi-solid forming method that combined a simple mechanical stirring treatment with the vertical semi-continuous casting process. Higher rotational speeds and higher casting temperatures during stirring yielded a finer as-cast structure and more uniform distribution of primary silicon particles in the matrix. However, these stirring conditions also led to transverse cracks on the billet surface. A mechanical vibration treatment using smaller amplitudes and lower frequencies during casting improved the cracked surface considerably, resulting in a structure comparable to that of the billet stirred at the same time.

Cu distribution around Q′-phase in an Al-1.0 mass% Mg₂Si-0.5 mass% Cu alloy has been investigated by the analytical transmission electron microscope (TEM), energy-filtering TEM (EFTEM), and high angular annular dark field scanning TEM (HAADF-STEM) techniques in order to determine the effect of Cu on the precipitation of this alloy. Cu-segregation around rod-shaped precipitates in the sample aged at 523 K for 24 ks was confirmed by energy dispersive X-ray spectroscopy, elemental maps, and HAADF-STEM images. Cu-segregation was also detected from small precipitates, which show a hexagonal network with a lattice constant of 1.04 nm in their HRTEM images. Coarse rods show homogeneous distribution of Cu, and chemical composition is similar to that of coarse Q′- or Q-phase. Small precipitates less than 10 nm were also confirmed in as-quenched samples, and those precipitates seem to form during quenching.

A novel low-temperature crystallization method is proposed; the excimer laser annealing (ELA) of amorphous silicon (a-Si) with a hydrogen-modulation-doped layer (ELHMD). The effects of hydrogen on low-energy crystallization by conventional ELA and ELHMD were investigated. As the hydrogen concentration increases, the crystallinity of the polycrystalline silicon (poly-Si) prepared at a low energy density improves. It is considered that the nucleation is enhanced by the desorption energy of hydrogen from the Si-H₂ bond during the Si melting. In addition, the film exfoliation by H₂ burst can be suppressed using HMD a-Si film.

The terahertz (THz) region, which lies between the microwave and infrared regions, offers a wealth of untapped potential. We generated widely frequency-tunable coherent THz waves from GaP crystal pumped using continuous-wave (CW) semiconductor lasers and compared it with pulse pumping using Q-switched high-power lasers at 1–1.2 μm. THz wave generation was based on difference-frequency generation via the excitation of phonon-polaritons in GaP. CW THz waves were generated from GaP by enhancing the power density of the pumping light from semiconductor lasers. The power and phase-matched condition for THz wave generation are discussed with respect to the pumping method compared to pulse pumping. Semiconductor lasers have light power stability with a narrow linewidth. Therefore, CW THz waves can be used as a light source in high-resolution THz spectroscopy, as well as in multichannel communication.

Poly- and single-crystalline SrO substituted BaTi₂O₅ (Ba_1−xSr_xTi₂O₅) were prepared by arc-melting and floating-zone (FZ) melting, respectively. Both showed a strong b-axis orientation and had maximum permittivity (ε_max) at 1 mol% SrO substitution. The ε_max values of poly- and single-crystalline Ba_0.99Sr_0.01Ti₂O₅ were 3300 and 42190, respectively. The Curie temperatures (T_c) of poly- and single-crystalline Ba_1−xSr_xTi₂O₅ at x=0.03 were 748 and 742 K, respectively. The electrical conductivity (σ) of single-crystalline Ba_1−xSr_xTi₂O₅ was higher than that of poly-crystalline Ba_1−xSr_xTi₂O₅. Larger size of single-crystalline Ba_1−xSr_xTi₂O₅ specimen than that of BaTi₂O₅ was obtained.

Boron carbide particulates reinforced 2024 Aluminum matrix composites were fabricated by mechanical alloying–hot extrusion technology successfully. The morphology and microstructure of B₄C_p/2024Al composite were investigated by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A clean interface of B₄C between aluminum was obtained in this experiment, and matrix alloy revealed the typical microstructure of high energy milling with average grain size about 300 nm. Nanosized oxide and carbide formed after the composites subjected to high energy milling and hot consolidation process. The yield strength and Young’s modulus values were improved significantly over the monolithic 2024 alloy.

Detailed characterizations are performed to identify the nanostructures of electrodeposited Ni-W alloys with grain size of 5 and 8 nm. Three-dimensional atom probe (3DAP) analyses have clarified that, in both alloys, experimentally measured W-concentration distributions fit well to the bimodal binomial distribution compared to the single binomial distribution. This result indicates the coexistence of W-depleted and W-enriched phases in the alloys. Nano-beam diffraction (NBD) patterns and energy dispersive x-ray spectroscopy (EDS) analyses revealed that the W-enriched phase is amorphous and that the W-depleted phase is nanocrystalline. The W-concentration visualizations on the cross section of 3DAP analysis volume identify them as amorphous/nanocrystalline duplex composites.

In this study, binary (copper and zirconium) amorphous metals with embedded nanosized crystal structures are subjected to uniaxial tension using molecular dynamics simulations to reveal the mechanism of shear band structure formation. The number and the size of the nanocrystals are chosen as the study parameters. The number of nanocrystals affects the stress-strain curve and shear band formation while the size of the nanocrystals does not significantly affect the results. As reported in the experimental work published so far, under tension coalescent voids are found in the shear bands or at the interface between crystalline and amorphous materials. The simulation results show that the number of shear bands under compressive loading is much larger than that under tensile loading. We also found that, even under compressive loading, the shear bands started from regions with enough free volume.

Phase relations of copper-zinc-sulfur ternary system have been investigated at temperatures of 1100 and 1200 K by equilibrating synthetic samples in evacuated sealed quartz tubes. Using the activities of copper and zinc in the copper-zinc binary system reported in literatures, the activities of the components in the copper-zinc-sulfur ternary system have been then calculated by applying the Gibbs-Duhem equations to the phase relation of metal-sulfide equilibrium. The reaction path of a new zinc distillation process, in which zinc sulfide is directly reduced to zinc vapor with metallic copper, and sulfur in zinc sulfide is fixed as copper sulfide, has been discussed in terms of the activities of the components in the copper-zinc-sulfur ternary system.

The hydrogen sorption of pure zirconium was investigated as a function of activation temperature. The sorption speed increased with activation temperature up to 750 K and decreased at higher temperatures. The X-ray photoelectron spectroscopy study revealed that oxygen peak virtually diminishes on heating at temperatures above 750 K. The cross-sectional TEM showed that the surface amorphous layer crystallizes on heating at 873 K. The structural transition from amorphous to crystalline state is attributed to the decrease in hydrogen sorption.

Anodic polarization testing of SUS304 stainless steel was carried out in an aqueous solution of 3.5 mass% NaCl at a potential increasing at a constant rate of 20 mV/min. When the current density reached 2, 10 or 50 A/m² within the pitting corrosion region, the potential was kept at a constant value for 600 s at each current density. The ultrasonic wave (UW) was applied to the specimen from the beginning of test or just after the current density reached one of these constant values. The current density in these cases was compared with that without the application of UW. The results indicated that when the UW was applied from the beginning of test the current density was not affected by the application of UW in both the cathode and passive regions, but the increase in current density was suppressed by UW when the potential was kept at the constant value after the current density reached 10 or 50 A/m². Also when the UW was applied just after the current density reached 2, 10 or 50 A/m² and the potential was kept at the constant value, the increase rate of current density was reduced by the application of UW. At the same time, the number and size of pits were decreased by the application of UW. The reason for the decrease in pitting corrosion was considered to be that UW destroyed the corrosion product on pits and the stirring effect of UW decreased the concentration of hydrogen and chloride ions in the pits, which accelerated the formation of a passive film on the pit wall.

The effect of Ca addition on the corrosion resistance of AZ31 magnesium alloys was evaluated by observation of microstructure and measurement of corrosion potential and average corrosion rate. The main mechanism of corrosion of AZ31+xCa (x=0∼5 mass%) alloys was galvanic-corrosion between α-Mg and second phase. But the propagation behavior of corrosion was different with Ca content. In the alloy containing below 0.7 mass%Ca, a micro-galvanic cell formed between matrix α-Mg and second phase formed semi-continuously at grain boundaries and the corrosion progressed in transgranular mode. The propagation of corrosion was retarded when the corrosion front met the second phase acted as corrosion barrier. But in the alloys containing above 1 mass%Ca, a micro-galvanic cell formed between eutectic α-Mg and discontinuous second phase in the eutectic region and the corrosion rapidly progressed along eutectic α-Mg formed continuously at grain boundaries because the discontinuous second phase could not prohibit the propagation of corrosion effectively.

A continuous hydrogen-removal method from aluminum melt, spray degassing, is presented. The equilibrium equation of this method is discussed theoretically. Theoretical equilibrium analysis shows that the final hydrogen content of the melt is only affected by the purging gas flow rate and the melt mass flow rate. The hydrogen content of the outlet melt always contains a constant during the whole degassing time. The final hydrogen content of the melt decreases with increasing purging gas flow rate and increases with increasing melt mass flow rate. Compared with the rotary impeller degassing method, spray degassing consumes less treatment time and purging gas volume. Experiments were conducted using the method to remove the hydrogen in aluminum melt. The experimental results show that, the spray degassing is a good hydrogen-removal method.

The strength of four binary systems NaCl–Na₂CO₃, KCl–K₂CO₃, KCl–NaCl and K₂CO₃–Na₂CO₃ was investigated in order to develop expendable salt core for high pressure die casting processes. Four point bending test was conducted to determine the strength of specimens made from molten salts by using the permanent mold casting technique. The strength of the system NaCl–Na₂CO₃ was over 20 MPa at the Na₂CO₃ composition between 20 mol% and 30 mol%, and between 50 mol% and 70 mol%. The highest strength was about 30 MPa at the composition of NaCl–70 mol%Na₂CO₃. This strength was 5 times as high as that of commonly used sand cores. The system KCl–K₂CO₃ also showed 20 MPa in strength. It was observed that there were the primary particles surrounded by the eutectic structure in the solidification structure of the systems NaCl–Na₂CO₃ and KCl–K₂CO₃ at the composition where the peak strength was obtained. The presence of the primary particles played an important role to strengthen the structure because the primary particles can prevent or deflect the crack propagation. In contrast to these binary systems, the systems KCl–NaCl and K₂CO₃–Na₂CO₃ were very brittle due to the phase decomposition or other solid–solid phase transformation of the solid solution phase. The strength of these systems was under 6 MPa.

The spark sintering technique was utilized for fabrication of titanium matrix composites consisting of a matrix of titanium and precipitated phases of TiB or TiN. Density of composites and amount of precipitated compounds could be controlled by variation of process parameters in the spark sintering. B₂CN or BN as starting powders was decomposed, and compounds consisting of Ti and N, or solid solutions of N and C in Ti matrix were formed. The hardness also increased by the increase of TiB or TiN contents. The spark sintering at the higher temperature, 1673 K, led to enough promotion of sintering and enough precipitation of TiB as a reinforced phase, which resulted in the increase of values in hardness. The wear was promoted by three different mechanisms, an adhesive type, abrasive type and a mixture of both types, depending on the TiB amount in composites. The amount of precipitated TiB of 11–17 vol% in composites was optimum for improvement of both friction and wear properties in tests under a ring (counterface: SUJ3)-on-disk (specimen: titanium matrix composites) configuration.

This paper discusses the grindability of sprayed coatings of Al₂O₃(-TiO₂). The actual grinding action was investigated experimentally by surface grinding using a resinoid diamond wheel with different particle sizes and concentrations.
The maximum height of the grinding surface was lower when the grain size of the wheel was larger and the degree of concentration of the wheel was higher. The abrasion of the grinding wheel was not due to the abrasion by the abrasive grain, but to a selective removal of the combining material during grinding and a reduction of the holding strength of the abrasive grain. This phenomenon was remarkable when the degree of concentration was low.

In the last 50 years, brazing of titanium and/or titanium alloys has been studied and a number of filler metals have been developed. Commercially pure titanium was brazed with commercially produced atomized brazing filler metal powder in an industrial vacuum furnace. Ti-Zr-based alloy filler metals were utilized in this study. We investigated the joint strength by shear strength tests and by observing the microstructure at the brazed joint. The shear strength tests revealed that the joint strength of Ti-Zr-based alloy filler metals for a brazing time of 60 min was approximately 300 MPa, which is almost the same as the base metal strength. Zirconium diffused into the base metal, thereby transforming from α-Ti to β-Ti for a temperature below the α-β transformation temperature of the base metal, and the diffusion of nickel and copper into the base metal was accelerated. The brazing filler metal remained at the brazed joint for a brazing time of 10 min; however, for an increased brazing time, it disappeared because of isothermal solidification. It is understood that isothermal solidification was mainly controlled by the diffusion of zirconium.

Resistance welding was applied to the bonding of SiC to metals. The welded interface structure was observed by high-resolution transmission electron microscopy to reveal the reaction during welding. The maximum bonding temperature of SiC varied with the rate of welding current rise. At the welded interface, Al₄C₃, Al and an amorphous phase were formed adjacent to SiC in the SiC/Al system. The SiC/Al interface was flat at the atomic level and the crystallographic orientation relationship between SiC and Al was observed. For the SiC/Ag-Cu-Ti alloy system, the reaction phases TiC and Ti₅Si₃ were formed at the interface. The thickness of the reaction phases varied with the rate of welding current rise, and, under specific welding conditions, Ag formed directly adjacent to SiC without the reaction phases.

Laser cladding of aluminium powders was performed on pure magnesium substrates using the blown powder method. The microstructure across the laser-clad track was studied. Starting from the bottom of the laser-clad to the top surface of the track, a series of microstructures was observed: a planar growth interface of the substrate, a narrow band of (β+γ) eutectic, a narrow band of β cellular structure, and finally a relatively thick layer of α-Al and (α+β) eutectic structure. The evolution of the various phases and microstructures is discussed in terms of the distribution of solute in conjunction with the Al-Mg phase diagram, temperature gradient and solidification rate, constitutional supercooling theory, and the condition for columnar-to-equiaxed crystal transition.

The effects of bonding forces and reflow process on the failure behaviors of anisotropic conductive film (ACF) interconnections were analyzed. Conventional reflow process was employed with peak temperatures of 220°C for soldering of Sn-37Pb and 260°C for soldering of Pb-free Sn-Ag or Sn-Ag-Cu. Two kinds of main failure mode were detected after double reflows at 220°C: formation of a conduction gap between conductive particles and Ni/Au-plated Cu pad, and delamination of the adhesive matrix from the plated Cu pad on the flexible substrate. The determination of the failure mode was mainly affected by the variation of the bonding force. The main failure mode of the reflowed ACF joints was conduction gap for the joints with lower bonding forces and adhesive matrix delamination for the joints with higher bonding forces. However, only adhesive matrix delamination was observed after reflows at 260°C. A theoretical calculation was also conducted to predict the connection resistance of the ACF joint before and after reflows. The calculation showed that the optimum bonding forces are between 65 and 70 N.

The possibility of combustion synthesis of perovskite-oxide thermoelectric materials with the attendant saving of energy and time and without deterioration in the thermoelectric properties was investigated by evaluating the thermoelectric properties of lanthanum-doped strontium titanate (Sr_1−xLa_xTiO₃, 0≤x≤0.1). The materials were successfully combustion synthesized and spark plasma sintered with 98.0–99.6% of true density, and their thermoelectric properties were evaluated from room temperature to 850 K. The optimal lanthanum doping amount ratio x in the considered temperature range was from 0.06 to 0.08, in which Sr_0.92La_0.08TiO₃ sample showed the maximum ZT of 0.22 at 800 K. This value was close to the highest recorded ZT at the same temperature up to now, and the ZT of most samples are higher than those synthesized by the conventional solid state reaction method. Thus, combustion synthesis is promising for producing perovskite-oxide thermoelectric materials for high-temperature application.

Co-29Cr-6Mo alloys consisting of 0∼1.76% Zr were prepared and heat-treated at 1210°C for 2 h or 1230°C for 3 h. Three types of precipitates were identified. With more than 0.37% Zr content, precipitates are mixtures of σ phase and (Zr, Mo)-rich phase. The σ phase dissolves into a matrix and the (Zr, Mo)-rich phases change its composition into a Zr-rich phase with heat treatment. An alloy with a solid solution containing 0.01% Zr exhibits improved mechanical properties.

A recovery method for electrode compounds from waste nickel metal hydride batteries by physical separation using sizing and distance-variable magnetic separation was investigated. The electrodes are formed by bonding substances of substrate and fine activating agents. Fine particle separation causes increasing costs and decreasing separation efficiency, suggesting a treatment flow where the separation of the anodic compounds from the cathodic compounds is carried out first and then each compound is crushed again for the liberation of activating agents and substrate. There is no suitable magnetic separation equipment to separate ferromagnetic substances using the magnetic property differences in the substrate components and special equipment to achieve this was developed. Using this newly developed equipment resulted in good separation.

The paper explains the heterocoagulation of micro-size particles and non-polar oil droplet in polar organic solvent in order to verify the mechanism of two-liquid flotation when separating fine powders. In other words, the zeta potential and the size of aggregated particles were measured, and then the total potential energy was calculated according to the DLVO theory. The results indicated that the heterocoagulation of one of fluorescent powders and n-heptane droplet in DMF solvent is feasible in the presence of surfactant ((1) in the presence of 2×10⁻⁴ mol L⁻¹ of DAA, heterocoagulation of green particle–n-heptane droplet, (2) in the presence of sodium 1-octanesulfonate 20×10⁻⁴ mol L⁻¹, heterocoagulation of blue particle–n-heptane droplet). Based on these results, the heterocoagulation mechanism of fine particles and non-polar oil in polar organic solvent was evaluated and thus the mechanism of two-liquid flotation of fine particles was elucidated. These findings are also verified by presenting a set of experimental results regarding the separation of a mixture of fluorescent powders.

The temperature dependence of specific resistivity and thermal conductivity for some Sn-Zn alloys was measured to use their values in electrical and thermal calculations on the basis of Ohm’s and Fourier’s laws, in order to obtain the temperature-distribution in lead-free fuse elements of electric power line. The interaction between microstructures and their properties was also investigated in Sn-Zn alloys. Specific resistivity and thermal conductivity could be estimated as a function of temperature and alloy composition in the compositional ranges classified from the standpoint of continuity or non-continuity of constituent phases such as primary Zn, Sn-solid solution and eutectic in microstructures of Sn-1 to 100Zn alloys. In the proposed estimations, not only volume fraction of Zn and Sn-solid solution phases but morphologies of both phases were considered in Sn-Zn alloys.

In the present study, hydrogen-absorbed Mg₂Ni intermetallic powders were prepared by mechanical alloying under an Ar atmosphere. Modification of the Mg₂Ni powders was attempted by adding silver (0.5, 1.0, 2.5, and 5.0 at%) into starting elemental powder mixtures. The as-milled powders were examined as a function of milling time by X-ray diffraction and synchrotron X-ray absorption techniques. In addition, the hydrogen absorption performance of the 15 h as-milled powders were evaluated. The experimental results show that (Mg₂Ni)_100−xAg_x powders exhibited a mixture of Mg₂Ni, magnesium and nickel solid solutions after 15 h of milling treatment. The maximum hydrogen absorption content and reversible hydrogen content of 15 h as-milled Mg₂Ni powders was 3.14 and 2.40 mass%, respectively. An improvement of hydrogen absorption properties can be noticed by doping silver, but the less silver addition the better performance. In the present study, (Mg₂Ni)_99.5Ag_0.5 exhibited the best hydrogen absorption properties where the maximum hydrogen absorption content and reversible hydrogen content was increased significantly to 3.93 and 3.14 mass% respectively. More than 25% improvement of hydrogen absorption for Mg₂Ni intermetallic powders was achieved by doping silver.

A thin Pd-Ag alloy film, which will be applied to fabricate membranes for hydrogen separation, was successfully deposited using an electroplating technique. The plating solution for the formation of a thin Ag-rich Ag-Pd film for electric contact consisted of PdCl₂, AgNO₃, HBr, and HNO₂. An improvement of the electrolytic bath was achieved by a pH control, which was kept constant at 6.6 and by the addition of H₃BO₃ and C₂H₅NO₂. When the concentration of PdCl₂ in the bath was increased to 4 times as high as that of the reported bath, the deposited film had the preferable composition of 72 mass% Pd and 28 mass% Ag. It was confirmed by SEM observations, and XRD, and EPMA analyses that the deposited film possessed a negligible amount of cracks and pinholes and was composed of Pd-Ag alloy without exhibiting any concentration gradient along the film thickness.

The effects of niobium and oxygen content on the mechanical properties, β phase stability and elastic deformation behavior of Ti-Nb-Ta-Zr-O alloys were investigated by employing tensile tests, microstructure observations and XRD analysis. The basic composition of the tested alloys used was Ti-36%Nb-2%Ta-3%Zr-0.3%O (mass%), with the other alloys having lower niobium content (from 32% to 36%) and higher oxygen content (0.5%). Orthorhombic α″ was observed in the specimens with lower niobium content. Work hardening and elastic deformation behavior in the specimens with lower niobium (33% to 34%) and higher oxygen (0.5%) contents are similar to those of the alloy with basic composition; these specimens showed little work hardening and non-linearity in the elastic range of tensile deformation. The phase configuration analysis of these specimen alloys does not show the presence of any peaks other than the β phase before and after cold working. The cold worked Ti-32%Nb-2%Ta-3%Zr-0.5%O has a Young’s modulus of 55 GPa, a tensile strength of 1370 MPa and a tensile elongation of 12%. After heat treatment at 623 K for 600 s, the tensile strength of the alloy reaches 1500 MPa, with a Young’s modulus of 58 GPa and a tensile elongation of 10%.

Making the angle of a hair clipper blade edge acute improves its cutting ability but causes the edge to be susceptible to wear, resulting in decreased cutting service life. When we used an electric hair clipper with a movable blade having a 45° acute angle on its edge, the edge caused significant wear and thus shortened its cutting service life. In this research, we conducted experiments on the cutting service life by cutting artificial hairs and, according to the experiment results, verified that using a high-hardness blade would suppress the wear of the blade edge to increase the cutting service life. Furthermore, assuming that “degradation in blade sharpness is subject to the wear loss of the blade edge and the wear loss depends on the distance at which the blade edge slides on the cross section of the hair; in other words, on the total number of strands of hair cut and the hardness of the blade materials”, we estimated the cutting service life from the blade hardness, and obtained excellent agreement between the estimated and test results. When using blades having different initial edge angles and radii, the concept of this cutting service life estimation enables us to facilitate estimation of their cutting service life.

Dispersed copper powder was prepared from cuprous oxide slurry by a wet chemical reduction technique with hydrazine. Palladium chloride (PdCl₂) was used to produce palladium (Pd) seed with its stabilizer, polyvinyl pyrrolidone (PVP) and sodium pyrophosphate (Na₄O₇P₂) was added as a dispersion agent. The formation and growth process of copper particles in the heterogeneous system were investigated in terms of reaction temperature and slurry concentration. As a general trend observed elsewhere, the average particle size of copper powder decreased from 420 nm to 150 nm with an increase of temperature from 313 to 353 K, while the shape of its number particle size distribution changed from bi-modal at low temperatures (313–323 K) to mono-modal at higher ones (333–353 K). Moreover, number size distributions of the powders produced at higher concentrations (2.5–40 g/L) all exhibit mono-modal shape while at 1.25 g/L it is bi-modal one. The explanation were based on the relationship between the number of Pd seed on the copper particles activated, which govern size and size distribution of final production in heterogeneous system, and the generation rate of Cu monomer at given conditions.

Following preparation of isolated nano-sized magnetite particles in a low-concentration dispersant solution, this study investigated the magnetic and optical properties. Magnetic measurements indicated that the magnetite nanoparticles exhibited perfect superparamagnetism above the blocking temperature. Optical measurements revealed that the magnetic films exhibited good transmittance in the visible region and excellent UVB absorption. It has potential for use in optical applications (UVB-cut), such as sunglasses, heat mirror film and others.

The effect of Ce-rich mischmetal (RE) contents on microstructures and mechanical properties of the AZ31-xRE (x=0, 1, 2 or 3 mass%) magnesium alloys is investigated. The constituent phases of AZ31 are α-Mg and few β (Mg₁₇Al₁₂). The intermetallic phase, Al₁₁RE₃, is precipitated in the α-Mg matrix after adding the RE into the AZ31 alloy. The amount and the granule size of Al₁₁RE₃ precipitates increase with increasing the contents of RE added in the alloy. The hardness of the AZ31-xRE alloys also increases with increasing the adding amounts of RE. The superior thermal stability of the Al₁₁RE₃ intermetallic can suppress the grain growth of AZ31-xRE alloys, thus the reduction of hardness of RE-containing alloys after solid solution treatment is less than that of the AZ31 alloy. The results of compression tests show that AZ31-xRE alloys present an inferior deformability and are fractured by the crack propagation along the direction of 45° with respect to the compression axis at room temperature. The compression formability of AZ31 is better than that of RE-containing alloys at the temperature above 473 K. The flow stress of testing alloys increases with increasing the strain rate, but with decreasing the compression temperature.

We report a ductile Fe-Mo-P-C-B bulk metallic glass (BMG) with good soft-magnetic properties. The Fe-Mo-P-C-B BMG with high Poisson’s ratio of 0.325 and low glass transition temperature of 708 K exhibits plastic strain up to 5.5% before final failure and high fracture strength of 3280 MPa in compression. The Fe-based BMG possesses high saturation magnetization of 1.1 T, low coercive force of 1.8 Am⁻¹ and high permeability of 55300. The Fe-Mo-P-C-B BMG with this combination of noticeable ductility, high strength and good soft-magnetic properties previously not observed simultaneously in Fe-based glassy alloys has promising potential in functional and structural applications.