The mechanical properties and processing performances of conventional magnesium alloys still could not meet the need of important application fields due to some demerits, such as poor formability, low creep resistance and unsatisfactory strength at elevated temperature. Recent investigations have shown that additions of strontium to magnesium alloys are effective in improving creep resistance of the alloys at temperatures above 150°C, and some new types of magnesium alloys containing strontium have been developed. The mechanical properties and microstructure of magnesium-aluminum based alloys containing strontium are reviewed, and the considerable discrepancy among the research results is discussed. Special attentions are paid to the mechanical properties, compounds and grain refinement of Mg-Al-Sr based alloys. The Sr/Al ratio is thought to be important to control the microstructure of Mg-Al-Sr alloys. The mechanism of grain refinement caused by strontium addition in magnesium alloys remains unclear.

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A molecular dynamics simulation was performed to study the microstructure and void distribution in amorphous SiO₂. Models were prepared at six temperatures and three densities. The microstructure of the simulated models was analyzed through partial distribution functions, coordination number, and bond-angle distribution. Two void aggregations were considered: void clusters (VCs) and void tubes (VTs). The calculation results showed several very large VCs with volumes as much as six times larger than that of a Si atom. A large VT, being the aggregation of 77% of all voids, was found in models and served as a fast diffusion path for O atoms. A weak change in short-range order as well as in behavior of void aggregation with temperature was observed. Furthermore, it was demonstrated that the large voids are “native” vacancies, whose concentration is independent of temperature. With an increase in system density, the void size became smaller and the void number became larger.

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Ti and Ni clusters have been formed, and codeposited on substrates using a new plasma-gas-condensation cluster deposition system, in which two DC glow-discharge-sources are installed in completely separated two sputtering chambers. Transmission electron microscope (TEM) observations of these codeposited specimens indicate that Ti and Ni clusters are randomly mixed with each other. Hcp Ti and fcc Ni diffraction rings are detected in selected area electron diffraction patterns, and no clear alloying can be detected at around the interface between Ti and Ni clusters in the high resolution TEM image. These results demonstrate that Ti and Ni cluster nanocomposites are obtained from this method.

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The effects of Cu and Fe additions on the thermal stability, microstructure and mechanical properties of Al₈₅-Ni_8.5-Mm_6.5, Al₈₄-Ni_8.5-Mm_6.5Cu₁, Al₈₄-Ni_8.5-Mm_6.5Fe₁ alloys, manufactured by gas atomization, degassing and hot-extrusion were investigated. All hot-extruded alloys consisted of homogeneously-distributed fine-grained fcc-Al matrix and intermetallic compounds. A substitution of 1 at% Al by Cu increased the thermal stability of the amorphous phase and produced alloy microstructure with smaller fcc-Al grains. On ther other hand, the same substitution of 1 at% Al by Fe decreased the stability of the amorphous phase and produced larger fcc-Al grains. The formation of intermetallic compounds such as Al₃Ni, Al₁₁Ce₃ and Al₁₁La₃ was suppressed by the addition of Cu or Fe. Among the three alloys examined, the highest Vickers hardness and compressive strength were obtained for Al₈₄-Ni_8.5-Mm_6.5Cu₁ alloy, and related to the finest fcc-Al grain size attained from increased thermal stability with Cu addition.

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Stress-induced martensitic transformation in Fe-Mn-Si alloys is characterized by the transformation of the fcc matrix to the hcp phase, which is generally reversible. In this study, Debye rings obtained by monochromated X-ray diffraction using synchrotron radiation were used for analyzing the structural change of the fcc matrix to the hcp phase in a polycrystalline austenitic Fe-Mn-Si-Cr alloy that was deformed by the tensile test at room temperature. Structural changes resulting from the reverse transformation due to heating were also studied. The results showed that the occurrence of the stress-induced martensitic transformation was not uniform, but depended on the relationship between the orientation of polycrystalline grains and the tensile direction. The transformation appears to preferentially occur in grains with large Schmid factors for the shear of [\\bar211](111) in the fcc matrix, and the formation of hcp phases also depends on the orientation of grains. The reverse transformation due to heating does not necessarily occur in the crystallographically reversible route. This indicates that irreversible deformation induced by dislocations during the tensile test restricts the reversible transformation of the alloy.

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The thermoelectric properties were examined of SiC specimens prepared by mixing α-SiC powder with B₄C, C, and Al₂O₃ and then sintering at 2100°C. Sintered specimens containing Al₂O₃ up to 3% with 0.5% B₄C and 2.5% C exhibited the highest densities. The electrical conductivities of these specimens increased with the Al₂O₃ content up to 3%. In contrast, the Seebeck coefficients of these specimens decreased with the addition of 1% Al₂O₃, but then barely decreased with the further addition of Al₂O₃. The maximum value of the power factor, 9.43×10⁻⁴ W/mK² at 800°C, was obtained with specimens sintered with 3% Al₂O₃ as well as B₄C and C. These results showed that the power factor of SiC ceramics could be enhanced by adding proper amounts of B₄C, C, and Al₂O₃ into them.

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In the present paper, the origin of midrib in lenticular martensite is clarified by examining the similarity between midrib and thin plate martensite in detail and studying the stress-induced growth behavior of thin plate martensite at various temperatures. Although lenticular martensite, especially midrib, exhibits a zigzag array in general, some martensite plates which are branched or kinked were also observed as thin plate martensite. The substructure of midrib is completely twinned and the orientation relationship of midrib with respect to austenite is close to Greninger–Troiano relationship. These morphology, substructure and crystallographic features of midrib in lenticular martensite are quite similar to those of thin plate martensite. Furthermore, stress-induced growth behavior of thin plate martensite changes with deformation temperature. Thermally-transformed thin plate martensite grows keeping a thin plate shape when deformed at temperature close to the Ms temperature. However, it grows into a lenticular shape accompanying a substructure with a high density of dislocations after deformation at temperature much higher than Ms temperature. Therefore, it is concluded that midrib in lenticular martensite is thin plate martensite itself. The difference between lenticular martensite and thin plate martensite is only in their growth behaviors.

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To develop long-life welded bellows for use under different pressure conditions, that is, atmospheric pressure and a high vacuum applied to the inside and outside of the welded bellows, respectively, a deformation analysis of welded bellows (Hastelloy C-22, 460 mm in external diameter, 370 mm in internal diameter, 0.475 mm in thickness) is performed by elastoplastic finite element analysis. The simulation results are as follows. In a conventional welded bellows used in an external-vacuum and internal-atmospheric-pressure environment, the external straight portion forms a vertical opening due to the pressure difference. The opening angle decreases by forming a slope on the external straight portion. The stress amplitude that occurs during the compression of a conventional welded bellows reaches its maximum in the vicinity of the external weld. The maximum value also decreases by forming a slope on the external straight portion. Fatigue life testing is performed on bellows produced on the basis of the simulation results. It is confirmed by fatigue life testing that forming a slope on the external straight portion is effective for extending the life of the bellows.

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Tungsten hemicarbide W₂C with no or small amounts of W or WC was prepared by reaction-sintering from W and WC powders using a resistance-heated hot-pressing technique called spark plasma sintering. The product phases, density, microstructure, elastic moduli, hardness, and fracture toughness of the sintered bodies were determined. The stable region of the W₂C phase had a narrow carbon content below 1860°C. W₂C had a Poisson’s ratio of 0.286, and its Young’s modulus at zero porosity was determined to be 444 GPa from the true density and bulk density dependence. These values suggest that W₂C has elastic deformation behavior similar to that of W.

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Hot rolling was conducted for Mg–6 mass%Al–2 mass%Ca alloy containing insoluble second phase particles and the mechanical properties of the rolled sheets were examined. The alloy used for rolling contained spherical particles with the size of 1.5 μm mainly in the grain boundaries. The amount of edge crack in the rolled sheets decreased at the rolling temperatures above ∼623 K. The highest strength and moderate elongation were obtained when the alloy was rolled at 623 K. The processing conditions for good workability under a given microstructure of the workpiece were considered from a viewpoint of relaxation of stress concentrations at the particle-matrix interface during rolling, and hot working diagrams were constructed. In order to attain good workability under the existence of relatively large second phase particles of 1.5 μm, it is required not only to activate the non-basal slip but also to make use of diffusional relaxation.

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The purpose of this paper was to investigate the effects of Nb on the microstructure and elevated-temperature mechanical properties of Alloy 690-SUS 304L dissimilar welds. The results show that the welds were dominant with dendrites and interdendritic phases. In the low Nb welds, the main interdendritic phases were Nb-rich and Al-Ti-rich phases. Cr-carbides were precipitated along the grain boundaries of the root region. In the high Nb welds, there were large Nb-rich phases in the cap region, while smaller Nb-carbonitride precipitates were found in the root region. The addition of Nb increased the hardness of the fusion zones. At 300°C, though the tensile strengths of all welds were higher than that of 304L, micro-cracks were unexpectedly found in the low Nb weld. Notched specimens were tested to characterize the mechanical properties of the welds. Both of the yielding and tensile strengths of the welds increased with Nb additions. On the fracture surface, the brittle fracture features also became noticeable.

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A dislocation bow-out model has been developed to explain the strength of ultra-fine grained (UFG) materials with grain size roughly between 20 nm to 500 nm. In the model, perfect dislocations are assumed to be nucleated at grain-boundary sources and bow out between two pinning points on a boundary. Yielding is considered to occur when a dislocation takes a semi-circular shape under applied stress. Statistical consideration is introduced to evaluate the most probable pinning-point distance as a function of grain size. Comparison with experimental results is made for fcc UFG metals. It is found that yield stress as well as thermal activation parameters can be explained reasonably by the present theoretical model.

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A compressive split-Hopkinson pressure bar is used to investigate the dynamic deformation behaviour, fracture characteristics and microstructural evolution of high-strength weldable aluminum scandium (Al-Sc) alloy at strain rates ranging from 1.3×10³ s⁻¹ to 5.9×10³ s⁻¹ under room temperature conditions. The stress-strain curves reveal that the dynamic mechanical behaviour response of the Al-Sc alloy is highly sensitive to both the strain and the strain rate. As the strain rate increases, the flow stress, work hardening rate and strain rate sensitivity all increase, but the fracture strain and activation volume decrease. The Zerilli-Armstrong FCC constitutive model is applied to describe the high strain rate plastic behaviour of the Al-Sc alloy. A good agreement is found between the predicted flow response and the actual response at all values of the applied strain rate. The Al-Sc alloy specimens fracture primarily as a result of a localised shearing effect. Scanning electron microscopy observations indicate that the fracture features are characterised by a transgranular dimple-like structure. The density and depth of the dimples decrease with increasing strain rate. Transmission electron microscopy observations reveal the presence of Al₃Sc particles in the matrix and at the grain boundaries. These particles prevent dislocation motion and therefore prompt a significant strengthening effect. The microstructural observations also reveal that the dislocation density and degree of dislocation tangling increase with increasing strain rate. The variations observed in the dislocation cell structure reflect differing degrees of strain rate sensitivity and activation volume and are found to be consistent with the observed stress-strain response of the Al-Sc alloy.

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Microstructural characteristics of warm-extruded magnesium alloy (Mg₉₇Zn₁Y₂) containing long-period stacking order (LPSO) phase has been investigated using SEM and TEM as the first step to understand the effect of warm-extrusion on its mechanical property. Particular attention has been paid on the microstructural change in the hcp matrix caused by warm extrusion.
The microstructure developed by the warm extrusion at 623 K consists of elongated grains with fine-lamellae of LPSO phase and fine-grained matrix of hcp phase. The grain size of the hcp matrix observed on the cross section perpendicular to the extruding direction was about 1 μm, indicating that remarkable grain refinement was occurred during the extrusion since the grain size of as-cast alloy was around 0.5 mm. Those fine grains in the extruded alloy included abundant stacking faults, and HAADF-STEM observation revealed that the stacking faults were enriched by Zn and Y. In addition, grain boundaries were also enriched by those solute elements, which must contribute to stabilizing such fine-grained structure.

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The microstructural change of the surface and the subsurface regions of a Si single crystal (Si(100)) after scratching tests under very small loading forces was investigated. First, the scratching tests were carried out using an atomic force microscope (AFM). Then, the profiles of those wear traces which were generated by the scratching tests were observed using a transmission electron microscope (TEM). TEM observations revealed that dislocations were activated in the sub-surface within less than 100 nm depth from the surface of the wear traces when the loading force was higher than 5 μN. When the loading force was higher than 20 μN, patches of amorphous Si was observed occasionally at the surface of the wear traces. High-resolution TEM (HRTEM) observations revealed that a dislocation introduced by the scratching test was a total dislocation with Burgers vector of 1⁄2⟨110⟩.

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Zirconium (Zr) and 12 mass% chromium containing ferritic stainless steels with Zr oxide dispersoids have been developed. In this study, the relationship between the process conditions and the metallurgical and mechanical properties were investigated. 12Cr-1Zr steel was consolidated with a grain size of about 1 μm by extrusion process of powder without mechanical alloying (MA). On the other hand, 12Cr-1Zr steels with MA process were shown to have a grain size of only about 0.36 μm or less. It was suggested that Zr atoms strongly reacts with gaseous impurities such as oxygen and carbon that were entrapped during MA. Based on TEM observations, Zr oxide and carbide preferentially precipitated on the grain boundaries which pin the grain boundary migration during the extrusion process. The developed steels follow the Hall-Petch relation and the slope is nearly identical to that of pure iron. Charpy impact values, at room temperature, of over 3 MJ/m2 up to tensile strength of 1500 MPa were obtained which is three times higher than those of conventional ferritic stainless steels or PH-stainless steels.

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As a fundamental study to develop a new process for eliminating detrimental antimony, recovering precious metals from the antimony-rich matte produced from the copper concentrate, and treating the occasionally generated speiss in nonferrous smelting processes, the phase relations in the Cu-Fe-S-Sb system saturated with carbon and the distribution of some minor elements between the phases in the miscibility gap, where three equilibrated phases of iron-rich alloy, copper-rich alloy and matte coexist, were investigated at 1200°C by using a quenching method.
The experimental results were compared with the results for the Cu-Fe-S-As-C system and discussed on the basis of activity coefficient of antimony in the matte phase at different matte grades. By utilizing the obtained data, material balance calculations concerning to the treatment of antimony-rich matte produced in copper smelting by adding the pig-iron was elaborated and also laboratory scale experiments using industrial matte were carried to corroborate the calculations. By using the phase separation, the cleaning of complex matte, the recovery of valuable copper, silver and gold into the copper-rich alloy and matte phases as well as the elimination of iron and an acceptable amount of antimony into the iron-rich alloy phase for discarding as a harmless and smaller deposit might be feasible.

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Niobium films with isolated columnar morphology have been prepared by oblique angle magnetron sputtering for capacitor application. Anodizing of the deposited niobium to form dielectric niobium oxide reduces the surface roughness, since the gaps between the neighboring columns are filled with the oxide due to large Pilling-Bedworth ratio for Nb/Nb₂O₅. To increase the gaps between neighboring columns, the influences of the angle of niobium flux to substrate and substrate surface roughness on the columnar morphology of the deposited films have been investigated using scanning electron microscopy and the electrochemical measurements. The deposition on the textured rough substrate surface and at higher angle of the niobium flux from normal to the substrate surface fabricates the niobium films with higher surface roughness.

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Transfer thermal plasma of argon (Ar) was applied onto the surface of 25 mol% Na₂O-SiO₂ molten slag using a hybrid plasma furnace composed of non-transfer and transfer thermal plasma. A tungsten rod was used as an electrode. The flame from the transfer plasma spread over the surface of the slag. The direct current of the transfer plasma was a maximum just after ignition and then decreased. When the transfer plasma was applied with a voltage less than 80 V, the iron dissolved and diffused into the molten slag as Fe²⁺ at the iron plate anode electrode according to Faraday’s law. For voltages over 90 V, oxygen gas bubbles evolved at the anode in addition to iron dissolution. SiO gas vaporized more than sodium (Na) gas from the slag surface, although the opposite phenomena should take place thermodynamically and kinetically. Furthermore, the quantity of SiO gas was 10 to 100 times more than that expected from Faraday’s law.

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The electrochemical behaviors of coating films on the steel and Ni–Cr–Mo alloy (Hastelloy) were investigated to obtain fundamental data on their corrosion resistance characteristics. We compared several types of materials and coating layers. SUS316, Hastelloy, DLC (Diamond-like carbon) on SUS316 and DLC on Hastelloy samples showed stable potential-time characteristics. F₂ processing SUS316 and F₂ processing Hastelloy samples showed negative direction change of the potential, and an active dissolution peak appeared in the F₂ processing SUS316 samples. On the other hand, DLC samples on SUS316 and Hastelloy showed a small anode current. It appeared that DLC coating was a superior resistance layer for the corrosion.

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The activity coefficient of strontium in a copper melt has been investigated by a chemical equilibrium technique in the temperature range from 1473 to 1773 K. A graphite crucible was used to control the oxygen partial pursuer in CO gas. The activity coefficient was derived from the standard free energy of formation of SrO, the oxygen partial pressure, and the concentration of strontium in copper.
The standard free energies of formation for SrO·6Al₂O₃ and SrO·2Al₂O₃ at 1723 K are also derived by equilibrating Al₂O₃, SrO·6Al₂O₃, and SrO·2Al₂O₃ with Cu.

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For characterization of corrosion resistance of metallic biomaterials, determination of trace amounts of metallic ions released from the materials in using static immersion into simulated body fluids (SBF) were investigated. In using a H₂SO₄-fume pre-treatment method, sensitive, precise and accurate determination of the trace metallic elements in SBFs could be performed by ICP-OES. For accurate analysis, it was necessary to employ a matrix-matched solution for the calibration. Moreover, usage of a PFA vessel in the static immersion test was recommended for the prevention of contamination. Thus, it was possible to determine μg dm⁻³ (ppb) order of elements in SBFs and evaluate nano-gram order of the released metallic ions.

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Alternating pulsed electrolysis was investigated for the surface modification of carbon steel substrates with carbon contents of 0.2 mass%, 0.6 mass% and 0.8 mass%. This process involves the anodic periodic dissolution of substrates to provide ferrous or ferric ions near the substrate as an electroactive component to form the objective alloy during subsequent cathodic times. The carbon steel substrates dissolved heterogeneously since the substrates had nonuniform texture composed of ferrite, cementite, and pearlite. Although the heterogeneous dissolution tended to provide a rough surface of the iron-chromium alloy layers, which resulted in poor adhesion of the layers, relatively flat and smooth alloy layers were obtained by reducing the amount of dissolved iron during each anodic pulse. Pits and defects that were originally recognized on the carbon steel substrate were gradually filled in and covered with iron-chromium alloy by the pulsed electrolysis.

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This research used pulse and direct current methods to perform surface anodizing treatment of Mg-9 mass%Li-1 mass%Zn alloy (LZ91). The anodic films were analyzed with electrochemical impedance spectroscopy (EIS) for corrosion resistance. The impedance measurements show that the resistance value of anodic films made by pulse current to be 100 KΩ at 2×10⁻² A/m² and those made by direct current anodic films to be 65 KΩ at 2×10⁻² A/m². It reveals that pulse current makes better anodic films than direct current. There were two layers in the anodic films that were verified from the EIS phase angle diagram in which three time constants existed. The structure of the film was analyzed by a FE-SEM, and the microstructure observation showed that the anodic film consists of porous and barrier layers.

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The influence of nonlinear friction stir welding (FSW) tool control on joint properties was investigated. Although FSW is widely applied to linear joints, it is impossible for five-axis FSW machines to maintain all FSW parameters in optimum conditions during nonlinear welding. Nonlinear FSW joints should be produced according to an order of priority for FSW parameters. Tensile test results of butt joints with rectangular change in the welding direction on the plate plane (L-shape butt joints) change with various welding parameters. Results show that a turn to the retreating side is encouraged when the welding direction changes. The method of zero inclination tool angles is effective for nonlinear and plane welding.

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Microtube is commonly used and required, particularly as micro components in micro-system technologies (MST) and micro electro-mechanical systems (MEMS). In this paper, fabrication process of microtube using superplastic dieless tube drawing was studied experimentally. Superplastic material used is Al-78Zn alloy tube with outer diameter of 2 mm and wall thickness of 0.5 mm. A high-frequency induction heating apparatus with air cooling nozzle was used for the dieless drawing. In the experiment of single pass dieless drawing, the effect of drawing conditions such as forming temperature, distance between heater and cooler and tensile speed on deformation profile, was clarified. Furthermore, in three-pass dieless drawing, a microtube with outer and inner diameters of 343 μm and 161 μm respectively can be fabricated successfully. In addition, from the experimental results and fundamental principles, it is confirmed that the ratio of inner to outer tube diameters maintains a constant value during dieless drawing. In other words, the geometrical similarity with the minimization of dimension is satisfied in this process. Finally, it is found that the surface roughness of microtube maintains a constant value in the dieless drawing process.

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An integrated numerical model is applied to simulate the mold filling and solidification phenomena as well as to predict the occurrence of the related casting defects for a brake disc casting. The goal is to conduct numerical experimentation to improve the running and gating system of the brake disc casting to obtain better casting quality. A computer-aided engineering software based on the finite element method is employed in this study. Numerical simulations are conducted for the brake disc casting with a preliminary running and gating system. The mold filling and solidification phenomena are examined to predict the occurrence and extent of the casting defects. They are found to be consistent with the defects observed in the actual casting. Based on the findings of the simulated results, a modified running and gating system is then proposed. The mold filling and solidification phenomena for the modified design are simulated. The results show that the problem of casting defects is alleviated with use of present results.

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The present research employs in-situ plasma Optical Emission Spectroscopy (OES) to explore the effect of microwave plasma jet chemical vapor deposition (MPJCVD) on activating CH₄+H₂ plasma environment and synthesizing diamond film. Surface morphology and main orientation of lattice plane of the diamond synthesized under different processing parameters are also examined. Since species such as CH, H₂, hydrogen Balmer alpha (H_α), carbon dimer (C₂) and hydrogen Balmer beta H_β in the plasma radical are easily influenced by gas concentration, substrate temperature and processing parameters, in-situ OES is employed to diagnose in-situ OES diagnosing is employed to composition of plasma species in the synthesis of diamond film. Our findings reveal that species such as CH, C₂ and H_β in microwave plasma jet have significant influence on grain size, surface morphology and H/C carbon concentration. The Raman spectrum measurement can prove the relationship between CH/C₂ species density and diamond surface morphology.

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New Zr-based metallic glass wires with and without bio-toxic elements of Ni and Al for the application to biomaterials were prepared by arc-melting type melt-extraction method and their characteristics were tested. The continuous metallic glass wires with a good white luster and smooth surface were obtained in various alloys such as conventional Zr-Al-Ni-Cu, Ni-free Zr-Al-Co-Cu, and Ni and Al free Zr-Ti-Co alloys. The Zr-based metallic glass wires exhibit high tensile strength reaching 1 GPa. Furthermore, the metallic glass wires showed good bending ductility and could be bent through 180 degrees without fracture. The Zr-based metallic glass wires achieve simultaneously high tensile strength, good bending ductility and high thermal stability.

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The solidification structure of the coating layer on hot-dip Zn-11%Al-3%Mg-0.2%Si-coated steel sheet was studied by means of metallographic examinations together with calculation of phase diagram based on Thermo-Calc. The solidification structure observed, which exhibited a combination of the Zn/Al/MgZn₂ ternary eutectic structure, the primary Al phase, and the MgZn₂ phase, turned out to be different from that predicted under an equilibrium state in the sense that MgZn₂ instead of Mg₂Zn₁₁ was observed under the present condition. Excluding the Mg₂Zn₁₁ phase from the equilibrium phase diagram, the metastable phase diagram was calculated. Excellent agreement was obtained between the calculation and the experiment in terms of the solidification structure of the coating layer. Consequently, MgZn₂ is considered to form easily as the metastable structure known as the Laves phase, because the high cooling rate associated with the present experiment does not provide any potential for peritectic-eutectic reactions, which usually occur in the equilibrium state. Furthermore, MgZn₂, which has a C14-type Laves structure and a high rate of nucleation in the liquid phase, is considered to cause the preferential Zn/Al/MgZn₂ ternary eutectic reactions.

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The solidification structure of a hot-dip Zn-11%Al-3%Mg-0.2%Si coated steel sheet with a slight Ti addition was investigated by EBSD. In every center of the primary Al phase of the alloy-coating layer, TiAl₃ was observed by a scanning electron microscope, which suggests that TiAl₃ acts as a heterogeneous nucleation site of the primary Al phase. The latter was revealed to have perfect lattice coherency with the nucleus TiAl₃ phase. The crystal orientation relationships between TiAl₃ and the primary Al are (001)_TiAl3||(001)_Al and [100]_TiAl3||[100]_Al, (100)_TiAl3||(001)_Al and [001]_TiAl3||[100]_Al, (102)_TiAl3||(110)_Al and [\\bar201]_TiAl3||[\\bar110]_Al, (110)_TiAl3||(110)_Al and [\\bar110]_TiAl3||[\\bar110]_Al, indicating that the primary Al phase grows in an epitaxial manner from the nucleus TiAl₃ phase. The planar disregistry δ between the two phases was calculated to be less than 5%, owing to this good lattice coherency. The TiAl₃ phase is considered to decrease the degree of undercooling necessary for the nucleation of the primary Al phase.

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Ceramic lined steel pipe is produced by a thermit process under a centrifugal force. A powdery mixture of ferric oxide and aluminum with silica is used. The addition of silica material has an important role for densification of the ceramic layer formed inside the pipe. It is found that the silicate materials of 2FeO·SiO₂ and 3Al₂O₃·2SiO₂ in amorphous state significantly extend the liquid phase longer and improve the layer structure density as cooling proceeds. Additionally, it is proposed that a mechanism of solidification and densification progresses through four steps for the ceramic layer formation.

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The magnetic properties and amorphous formation ability of Pr-based alloys have been reported and discussed. In this paper, Pr₉₀Fe₁₀ alloys were studied to reveal the solidification behavior associated with undercooling, magnetic properties of the metastable phase, and relation between undercooling and metastable phase formation by using the gas flow levitation method. The samples were solidified at various cooling rates from approximately 50 K/s to approximately 270 K/s. Undercooling increased with the cooling rate. According to the results of the SEM-EDS analysis, the Pr₉₀Fe₁₀ samples that solidified at high undercooling conditions in eutectic reactions consist of the primary α-Pr, eutectic α-Pr, and metastable phases whereas the samples that solidified at low undercooling conditions in eutectic reactions consist of the primary α-Pr, eutectic α-Pr, and Pr₂Fe₁₇ phases. Additionally, the magnetic properties changed due to the undercooling.

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There were many techniques of joining two or three materials. A new metallic liquid jointing technique which enables the joint of Zr₅₅Cu₃₀Ni₅Al₁₀ bulk glassy alloy without any crystallization is very useful to produce a large bulk metallic glass. Molten alloy streams with high velocity are generated by ejection of alloy liquid through two nozzles at different sites. The jointed region has nearly the same structure, thermal stability and mechanical properties as those for the original glassy Zr₅₅Cu₃₀Ni₅Al₁₀ alloy. The successful joint method can produce the large glassy Zr₅₅Cu₃₀Ni₅Al₁₀ rod of 600 mm in length and 3 mm in diameter.

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To obtain basic data for developing manufacturing processes for stainless steels for implant application, we determined how solution treatment and cold rolling affect the microstructure and mechanical properties of stainless steels. The grain size of the austenitic (γ) phase in solution-treated ISO 5832 stainless steel tended to increase with solution-treatment temperature. The effects of solution-treatment temperature on the 0.2% proof strength (σ_0.2%PS) and ultimate tensile strength (σ_UTS) of this stainless steel were almost negligible, while total elongation (T. E.) tended to increase slightly with solution-treatment temperature. The mechanical properties of ISO 5832 stainless steel solution-treated at 1075°C for 30 min were as follows: σ_0.2%PS, 303±3 MPa; σ_UTS, 670±2 MPa; T. E., 65±2%; and reduction of area (R. A.), 71±2%. In the TEM image of 20% cold-rolled ISO 5832 stainless steel, many dense dislocations, which were produced by cold rolling, were observed. The σ_0.2%Ps and σ_UTS of the cold-rolled stainless steel increased as the draft increased, whereas the T. E. decreased linearly with an increase in the draft. The σ_0.2%PS, σ_UTS, T. E., and R. A. of 20% cold-rolled ISO 5832 stainless steel were 758±6 MPa, 890±2 MPa, 22±2%, and 68±4%, respectively. In the microstructural observation of solution-treated high-N stainless steel, CrNbN and Mn₂SiO₄ were observed. The mechanical properties of this stainless steel were as follows: σ_0.2%PS, 436±4 MPa; σ_UTS, 830±4 MPa; T. E., 37±2%; and R. A., 48±7%.

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Thermodynamic and magnetic properties of GdPd hydride (deuteride) were studied. Each of the pressure-composition isotherms of GdPd-Q (Q=H or D) systems showed a plateau region in 0.05<[Q]/[GdPd]<0.4, though hydrogen induced disproportionation of GdPd was observed above [Q]/[GdPd]>0.4. The disproportionation products were determined to be GdQ₂ and Gd₃Pd₄. Enthalpy changes for GdPd hydride formation at [Q]/[GdPd]=0.2 were evaluated from the isotherms to be ΔH_f^°=−130 kJ/mol_H2 and −122 kJ/mol_D2. Magnetization measurements revealed that the effective magnetic moments of GdPd and its hydride were approximately the same as that of Gd³⁺. This indicates that magnetic properties of GdPd and its hydride are governed by gadolinium atoms. In fact, the magnetic ordering temperature and the paramagnetic Curie temperature were also found to be almost invariable with hydrogen content, revealing that electrons from the 1s orbital of absorbed hydrogen bring little influence on the nature of 4f-electrons of gadolinium.

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We have studied the formation and carried out an in vivo evaluation of carbonate apatite (CO₃-Ap) and CO₃-Ap/CaCO₃ composite coatings on titanium substrates using the thermal substrate method. The coatings were formed on commercial pure titanium rods (diameter = 2 mm, length = 5 mm) and plates (thickness = 0.3 mm) by the thermal substrate method in an aqueous solution that contained Ca(H₂PO₄)₂, CaCl₂, and NaHCO₃. The coating experiments were conducted at 40–140°C and pH=8 for periods of 15 or 30 min. The coating temperature and NaHCO₃ of the solution had a significant influence on the surface morphology (net-like, plate-like, needle-like, or sphere-like), the phase (single phase of CO₃-Ap or binary phase of CO₃-Ap and CaCO₃), and the carbonate content in the precipitated films. A subsequent autoclave treatment also had an effect on the films. A coated rod was implanted in a 10 weeks old male rat’s tibia with a non-coated titanium rod being used as a control. The constructs were retrieved after a period of 14 d postimplantation and examined for new bone formation and for tissue response in the cancellous and cortical bone parts, respectively. Single-phase sphere-like CO₃-Ap had high osteoconductivity in the cortical bone region, and this increased with increasing carbonate content in the films. However, the osteoconductivity of the CO₃-Ap/CaCO₃ composite coatings decreased with increasing total carbonate content.

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The diffusion of Re and Ru in the γ′-Ni₃Al phase has been investigated at a range of temperatures 1423–1523 K by using the pseudo-binary diffusion couples. It was found that the concentration gradient of Re appeared to promote the uphill diffusion of Al, whereas that of Ru did not promote the Al uphill diffusion. The cross interdiffusion coefficients of \\ ildeD_AlRe^Ni and \\ ildeD_AlRu^Ni were independent of the matrix ordering since they were comparable qualitatively between those in the γ′-Ni₃Al and in the γ-Ni phases. The tracer diffusion coefficients for Re and Ru in Ni₃Al were estimated by extrapolation and the obtained activation energies were consistent with the site preferences of the elements reported in the literature. Further, the results of this work suggest that the diffusion of Ru in Ni₃Al is mostly governed by the diffusion in Ni sublattice and the diffusion of Re is mainly controlled by the formation of anti-site defects in the Ni sublattice with negligible contribution of the anti-site bridge mechanism.

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An amorphous Sm₅Fe₁₇ melt-spun ribbon was annealed under various conditions to obtain the metastable Sm₅Fe₁₇ phase. The Sm₅Fe₁₇ phase could be obtained by annealing at temperatures between 873 K and 973 K for 0.1–1 h. However, the annealed specimens contained other phases such as the SmFe₂ and SmFe₃ phases depending on the annealing conditions. It was found that the specimen annealed at 873 K for 1 h consisted mostly of the Sm₅Fe₁₇ phase. The Sm₅Fe₁₇ phase could also be obtained by annealing the amorphous Sm₅Fe₁₇ melt-spun ribbon at 1073 K for 0.1 h or 0.3 h, but annealing at that temperature for 1 h resulted in decomposition of the metastable Sm₅Fe₁₇ phase and formed the equilibrium Sm₂Fe₁₇ and SmFe₃ phases.

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Microstructures and mechanical properties of spark plasma sintered (SPS) Al₂O₃-Co composites were investigated depending on the sintering temperatures (900–1200°C) and cobalt contents (0∼12 mass%). The material properties of relative density and fracture toughness increased as the sintering temperature and Co content (up to 12 mass%Co) increased. In the SPSed Al₂O₃-Co composite sintered at 1200°C, maximum values of relative density and fracture toughness about 99.3% and 8.1 MPam^1⁄2, respectively were obtained. The fracture morphology of SPSed Al₂O₃-12 mass%Co composite showed a semi-brittle fracture mode due to the homogeneous dispersion of fine-sized Co particles.

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Magnesium and its alloys are potential candidates for bioabsorbable stents. The degradation rate of an indwelled magnesium stent is expected to be controlled under a blood flow. The influence of the controlled flow on the polarization and impedance behavior of pure Mg was thus investigated in a 0.6 mass% NaCl solution using a rotating electrode. The existence of a flow caused an increase in the anodic current density as well as a decrease in the impedance for a few hours of immersion, indicating the acceleration of Mg dissolution and the retardation of the growth of the surface hydroxide film. Interestingly, the existence of a flow retarded the breakdown of the surface film. After the surface film was broken down, the impedance did not depend on the rotation speed. To precisely evaluate the degradation rate of magnesium and its alloys for use in stents, the flow rate of the test solution should be controlled.

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Wettability of lead-free solders (Sn-3Ag-0.5Cu, Sn-8Zn-3Bi, and Sn-9Zn) on Au-plated copper substrate was investigated with three different thicknesses of Au layer (0.1 μm, 0.3 μm, and 0.5 μm). The contact angles of solder alloys did not show a dependence on Au thickness. The contact angles of Sn-3Ag-0.5Cu and Sn-9Zn decreased, whereas the contact angle of Sn-8Zn-3Bi remained constant with an increase in temperature. Wetting balance test results indicated that thickness of Au plating affects wetting force, with thinner plating showing stronger wetting force and therefore, lower wetting time. Effects of different fluxes on wettability were also studied.

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This study develops a new technology for conjugation between surface-modified Fe₃O₄ nanoferrofluid and DNA that can be applied for biological sensors. After fabrication by chemical disposition and thorough washing, centrifuging and sieving, pure Fe₃O₄ nanoferrofluid with mean particle size of 15 nm was obtained. PVP-k30 (Polyvinyl pyrrolidone) acts as dispersant to maintain a stable suspension of the Fe₃O₄ nanoferrofluid, which is then added to and fully mixed with deionized water (ddwater) (pH >7). Experimental evidence shows that the surfaces of the Fe₃O₄ particles carry positive charge and can effectively create a conjugating reaction with DNA. In addition, this TiO₂ nanofluid with mean particle size of 20 nm and high suspension stability is used to conjugate with another type of DNA. Finally, two sets of fluids, Fe₃O₄ and TiO₂, that have undergone conjugating reactions with different types of DNA are mixed in a culturecell, so they are linked together through the hybridization between different types of DNA. By spectrophotometer analysis, it is shown that DNA still exists in the fluid after hybridization, verifying that the hybridization technology between different types of DNA developed in this study is very successful.

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Phase equilibria between the γ and γ′ phases at 900°C in the Co-(10–70)Ni-Al-W system were determined by electron probe microanalysis (EPMA) and X-ray diffractometry (XRD). It was found that the γ′ phase with L1₂ structure continuously exists from the Co side to the Ni side in Co-Ni-Al-W system and that it widens to the low W region with increasing Ni content. The partition of Al into the γ′ phase increased with Ni content, while the W changed from a γ′ former to a γ former by increase of Ni content. Differential scanning calorimetry (DSC) measurements also revealed that the γ′ solvus temperature increases with Ni content, while the solidus temperature is hardly affected by such content. The lattice parameter of the γ and γ′ phases and the mismatch decreased with increasing Ni content, which caused the morphologic change of the γ′ precipitates from cubes to spheres.

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Nanocrystalline Fe-W composite is synthesized through the reduction of iron oxide/tungsten oxide (Fe₂O₃/WO₃) mixture with pure hydrogen gas at 700–1000°C. AR grade Fe₂O₃ and WO₃ powders were mixed thoroughly in ball mill and compacted. The dried compacts were isothermally reduced in pure hydrogen at 700, 800, 900 and 1000°C. Based on thermogravimetric analysis, the reduction behavior and kinetics reaction mechanism were studied. The initial oxides mixture and the various reduction products were characterized by XRD, SEM, VSM and reflected light microscope to reveal the effect of hydrogen reduction on microstructure, magnetic properties and reaction kinetics of produced Fe-W composite. Complete reduction was achieved with the synthesis of nanocrystalline (36.3 nm) homogenous Fe-W composite. Arrhenius equation with the approved mathematical formulations for the gas solid reaction was applied for the calculation of the activation energy values and detecting the controlling reaction mechanism.

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New bulk metallic glasses exhibiting a high glass forming ability were formed by a substitution of Hf and Nb for Zr and Ti in quaternary Cu-Ni-Zr-Ti system. An 8 mm-diameter BMG rod was obtained at the Cu₅₀Ni₈Zr₁₅Hf₃Ti₂₃Nb₁ composition by suction casting method. The glass transition temperature, crystallization temperature and reduced glass transition temperature of the BMG were 699 K, 754 K, and 0.59, respectively. Making an alloy system more complex was useful to increase the GFA.

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