Microstructural changes and phase transformation of Zn-Al based alloys (ZA alloys) were systematically investigated during various thermal and thermo-mechanical processes using X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe micro-analysis (EMPA), transmission electron microscopy (TEM), electron back-scattered diffraction (EBSD) and differential scanning calorimeter (DSC) etc. techniques. Phase decompositions of the alloys were studied under various thermal and thermo-mechanical circumstances. General rule of phase decomposition (II) (On effects of external stresses on phase transformation) was summarized with explanations from point view of Gibbs free energy.

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The giant magnetoimpedance in Ti/CoP plated wires with various CoP thickness was investigated. There is an optimal thickness of CoP magnetic layer for obtaining a large magnetoimpedance. The frequency ƒ_Z where the maximum magnetoimpedance (ΔZ/Z>₀)_max occurs, shifts to low frequency with an increase of CoP thickness. Such shift is correlated with the reduction of the effective critical frequency of skin effect, accompanying the increase of magnetic layer thickness. The magnetic anisotropy field H_K for Ti/CoP composite wires depends not only on the radial distance of CoP from the axis of the wire, but also on the CoP thickness.

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In this paper, n-type lead telluride (PbTe) compounds without doping were sucessfully prepared at high pressure and high temperature (HPHT). The carrier type was induced by the effect of pressure. The results of the electrical conductivity, Seebeck coefficient, thermal conductivity for n-type PbTe, which were measured at room temperature, show that the PbTe samples prepared by HPHT exhibit the same characteristics as heavily doped semiconductors. The figure-of-merit, Z, of 5.46 × 10⁻⁴ K⁻¹ was obtained, which is higher than the heavily doped samples of PbTe at room temperature. These results indicate that this method has potential application in obtaining good quality thermoelectric materials with improved properties.

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Precipitation in deformed and undeformed Al-300 ppm Fe alloy has been investigated by means of resistivity measurements and transmission electron microscopy. The undeformed specimens were solution-heat-treated at 913 K for 3.6 ks, quenched in iced water and then aged at the temperatures between 393 and 848 K, while the deformed specimens were cold-drawn for resistivity measurement or cold-rolled for TEM observations after the same solution heat treatment, and then aged. Resistivity in the undeformed specimens decreased in two stages, while in the deformed specimens, resistivity decreased in two or three stages depending on aging temperatures. Time-Temperature-Precipitation (TTP) diagram for the undeformed specimens consisted of one C-curve which corresponded to precipitation of stable Al₃Fe. The TTP diagram for the 65% cold-drawn specimens was separated into two C-curves: the curves in high and low temperature ranges corresponded to precipitation of Al₃Fe and Al₆Fe, respectively. The precipitation of metastable Al₆Fe was observed only in the cold-rolled specimens. Acceleration effects of cold drawing on Al₃Fe precipitation were hardly recognized.

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Optical metallographic techniques for grain-size measurement give unreliable results for high pressure diecast Mg-Al alloys and electron back-scattered diffraction mapping (EBSD) provides a good tool for improving the quality of these measurements. An application of EBSD mapping to this question is described, and data for some castings are presented. Ion-beam milling was needed to prepare suitable samples, and this technique is detailed. As is well-known for high pressure die castings, the grain size distribution comprises at least two populations. The mean grain size of the fine-grained population was similar in both AZ91 and AM60 and in two casting thicknesses (2 mm and 5 mm) and, contrary to previously published reports, it did not vary with depth below the surface.

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Rapid-solidified ferromagnetic shape memory Fe-30.2 at. %Pd alloy ribbon has a large magnetostriction more than 1.0 × 10⁻³ (= 1000 μ-strain). This type of magnetostriction is caused by the re-arrangements of martensitic twins (i.e., variants) by the applied magnetic field, therefore, it is generally very sensitive to the crystalline texture and twin's morphology of material. In order to develop a more high performance magnetostrictive actuator material driven by smaller magnetic field, the effect of grain and twin boundary microstructures on megnetostriction was studied by changing the condition of heat treatments. For the sample with strongly (100) textured grains after oil-bath quenching, a steep increment and large strain of 0.7 × 10⁻³ was induced at a fairly low magnetic field of 35 k A·m⁻¹ (= 1.5 kOe) when the magnetic field was applied normal to the ribbon surface. On the other hand, for the sample with randomly oriented grains and excessive existence of twin boundaries by ice-water quenching after long time annealing, the induced strain was initially small and then it gradually increased up to 0.6 × 10⁻³ at 70kA·m⁻¹. This difference of sensitivity in magnetostriction behavior is discussed from the viewpoint of magnetic domain mobility in connection with grain and twin boundary microstructures.

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A novel process where a specimen is rotated during a slip casting under a high magnetic field has been proposed to fabricate highly textured ceramics. The usefulness of the newly proposed process has been confirmed in Si₃N₄ ceramics processing. In the substance which the magnetic susceptibility in a, b axis is higher than that in c-axis, χ_c < χ_a,b, one directional crystal orientation can not be obtained in a slip casting under a high magnetic field because the free choice of crystal orientation exists in a, b axis. The one directional crystal orientation of Si₃N₄ with χ_c < χ_a,b has successfully been demonstrated in the new processing. The novel concept will provide a wide application to control the crystal orientation in various substances with the magnetic anisotropy of χ_c < χ_a,b.

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The electrodeposition of Fe-Ni alloys was performed galvanostatically in the sulfate solutions of pH 1—3 at 40°C and the alloy deposition behavior was compared with that of Zn-iron-group metal alloys to investigate their codeposition mechanism. The deposition behavior of Fe-Ni alloy showed a typical feature of the anomalous codeposition, in which electrochemically less noble Fe deposits preferentially under most plating conditions. The anomalous codeposition behavior in Fe-Ni alloy deposition was evidently dependent on the pH buffer capacity of the solutions. This can be explained in terms of the preferential adsorption of FeOH on the deposition sites of more noble Ni due to the extremely smaller dissociation constant of FeOH⁺ than NiOH⁺ in the multi-step reduction process of hydrated iron-group metal ions.

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The detection of damage to and fracture of cold forging tools during forming operation by fractal property of acoustic emission (AE) is performed. First, a tensile test on tool steel is conducted to elucidate the fractal dimensions of deformation-induced and fracture-induced AEs. The resultant fractal dimensions are 1.97 and 1.44. Next, the change in the fractal dimension of AE from a die insert is investigated under cold forward extrusions. Workpieces with a conversion coating film are used to eliminate the effect of friction on AE. After 300 extrusions, no damage and wear is observed on the die surface, and the fractal dimension is almost constant at 2.04 on average. Then, another series of cold forward extrusions under high-friction conditions is performed with mineral oil VG2 and stearic acid to promote the onset of damage to and fracture of the die. A defect on the surface of the workpiece is observed at the 101st extrusion, which resulted from the onset of crack on the die radius. The former average fractal dimension, 2.01, of the onset of the crack changes to 1.52 after the onset of the crack. From the results, the fractal dimension can be concluded to be one of the most effective indicators of the progress of damage to a cold forging tool. Finally, a method of separating the die-induced AE from the total AE based on the Kaiser effect is proposed.

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The microstructures and mechanical properties of the AZ31 Mg tubes fabricated by one-pass forward piercing tube extrusion are examined. The grain size is refined from the initial ∼75 μm grain size down to 2—3 μm. The room temperature uniaxial tensile elongations, measured along an axis that is 0°, 45°, or 90° with respect to the extrusion direction, are satisfactory, ranging from 20 to 50%. However, room temperature tube hydroforming, under a more complicated stress state, results in poor formability as a result of the strong basal plane texture. Rationalization in terms of Schmid factor analysis on the data obtained from the pole figures yields consistent results. Solutions for such difficulty are proposed.

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Pure pervoskite phase Pb_1.15(Zr_0.53Ti_0.47)O₃(PZT) powders were prepared by a chelating acetate sol-gel process. Powders obtained from two different heating temperatures, namely as-dried H.T powders (573 K/30 min) and as-dried L.T powders (423 K/10 h) were analyzed. Both the powder samples were investigated by Fourier Transform Infrared Spectroscopy (FT-IR), Differential Thermal Analysis/ Thermal Gravimetric Analysis (DTA/TGA) and Transmission Electron Microscopy (TEM). The combined results indicated that as-dried H.T powders contained a higher mole fraction of acetate groups and that the polycondensation was slower, resulting in a smaller particle size. H.T series is a better, shorter, low-budget, and more energy-economic procedure compared with the conventional heating procedure.

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Titanium nitride/hydroxyapatite functionally graded implant (TiN/HAP) was successfully fabricated by spark plasma sintering method (SPS) and their properties were investigated. The functionally graded materials (FGM) with the concentration from TiN at one end to HAP at the other were prepared by sintering at 1100 and 1200°C under the pressure of 150 MPa. The Brinell hardness was around H_B 60, nearly uniform for the whole range of composition. After 2 and 8 week implantation in diaphysis of femur of rat, there was very little inflammation and the new bone was formed around the sample. By use of TiN instead of Ti, the decomposition of HAP during sintering process could be suppressed and the successful sintering of FGM and mechanical properties could be attained.

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TiB₂ particle reinforced Cu matrix composites were fabricated by a combustion reaction between Ti and B in a Cu-Ti-B system. Addition to the fabrication of the composite, its bonding with 1050 Al alloy were successfully carried out in a single-step process by using the high heat of the combustion reaction. When the combustion synthesis of Cu-50 vol%TiB₂ was attempted, a minute quantity of unfavorable Cu₃Ti was formed with TiB₂ in the Cu matrix. However, for Cu-60 vol%TiB₂, only fine TiB₂ particles below 4 μm in diameter were formed in situ, and homogeneously distributed in the Cu matrix. Also for Cu-70 vol%TiB₂, the combustion reaction occurred completely without forming any unfavorable phases, although some Cu was evaporated during synthesizing the composite. In a Ti-B binary system, any reaction was not generated in the temperature range from room temperature to 1473 K. However, in the Cu-Ti-B ternary system, the combustion reaction was generated near the melting point of Cu, suggesting that it was activated by molten Cu. Preheating before inducing the combustion reaction was effective in bonding with long Al rods and also in reducing bonding defects. Intermetallic compounds consisting of Al, Cu and Ti were observed with unreacted B in the bonded layer. For the bonded specimen with a Cu insert layer, a eutectic microstructure of Al and Cu was formed between the Al alloy and Cu insert, and unreacted B was observed with a compound of Cu and Ti between the composite and Cu insert. The bonding strength was improved by inserting the Cu layer and by preheating. The bonded specimen with no insert layer was fractured between the composite and the Al alloy. By inserting the Cu layer with preheating, the fracture occurred between the Al alloy and the Cu insert.

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To understand a void formation mechanism in electroplated Cu interconnects used for Si-ULSI (ultra-large scale integrated) devices, microstructures of Cu films which were prepared by the electroplating technique using plating baths with or without organic additives were investigated by transmission electron microscopy (TEM). In the as-deposited samples, a high density of micro-voids were observed at the interface between a seed Cu layer and the electroplated Cu film which was prepared in the plating bath with organic additives. Growth of the micro-voids was observed in the samples annealed at elevated temperatures in an atmosphere containing hydrogen, whereas no void growth was observed in the samples annealed in Ar atmosphere. No void formation was observed in the Cu films which were prepared in the plating bath without organic additives. The present results suggested that the void formation in the electroplated Cu films was induced by existence of impurities such as organic additives or oxygen in the Cu films, and that the void growth was strongly enhanced by annealing in hydrogen.

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Ni₃Al is known as promising high-temperature structural materials because of its excellent high temperature strength and corrosion/oxidation resistance. Recently, we found that Ni₃Al shows high activity for methanol decomposition (CH₃OH → 2H₂ + CO), and little effect for steam reforming of methanol (CH₃OH + H₂O → 3H₂ + CO₂) in the case of feeding methanol and water. In the present study, we examined the catalytic activity of Ni₃Al powders by feeding pure methanol at a reaction temperature range from 523 to 633 K. It was found that Ni₃Al shows not only a high activity for the methanol decomposition but also suppresses the methanation. The catalytic properties of Ni₃Al were compared to that in the case of feeding both methanol and water.

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Germanium-doped zinc oxide thin films with Ge content of 0∼8.1 at% were deposited by an RF magnetron sputtering. The electrical and optical properties of the films were investigated. The Ge doping caused the reduction of resistivity of the films, and at about 3% of the Ge content showed the minimum resistivity of about 2 × 10⁻³ Ωcm. With high content of Ge, however, the crystalline structure changed and the resistivity of the film increased.

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Planning transition from conventional mass production, mass consumption, and mass disposal society to JUNKANGATA-SHAKAI (recycling-oriented society), requires detailed and accurate information concerning material flows, especially from the viewpoint of dematerialization. However, as is well known, it is nearly impossible to observe every material flow directly. Hence, the importance of Material Flow Accounting model has increased. In this study, a Material Flow Accounting model using input-output technique is developed for Japanese metal flows. Since the model uses the Input-Output framework, it can be easily integrated with the MIOT (Monetary Input-Output Table) for further simulation. However, the scope of this study is limited to static framework, because the primal goal is accuracy. The data for year 2000 is organized with the developed framework, and gives the following results. Firstly, scraps play significant roles already. Second, non-ferrous metals can be grouped into two types. The first group's destination is mainly construction and machinery and these non-ferrous metals show the similar pattern of destination as iron. This indicates that the flows can be roughly predicted from the iron flows. The other group shows no uniform trend so that the flows are more difficult to predict than the first group.

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Lead-free solder is a focus of increasing international attention, particularly in the wake of various EU directives (ROHS: on the restriction of the use of certain hazardous substances in electrical and electronic equipment). Lead-free solder is anticipated to reduce toxic environmental impact, but it has been pointed out that energy consumption and other related impacts like global warming caused by the production of lead-free solder may be higher than those for conventional solder. It is necessary to consider this trade-off relationship between types of environmental impact. The aim of this study is to conduct trial calculations of impact assessments of typical lead-free solders and a conventional Sn-Pb solder. Impact categories at the local level are regarded as important in the assessment of current materials, such as impacts caused by exposure to hazardous substances. For these impact categories, the resultant environmental impacts can differ greatly, depending on where emissions occur, even for the same degree of environmental burden. Therefore, LIME (Life cycle Impact assessment Method based on Endpoint modeling) was preferentially used, based on domestic background data. Using a conceptualized damage assessment and damage indicator of human health, we concluded that the avoidance of lead is effective even when the increase in other health impacts are taken into account. The reliability of this result was confirmed by the implementation of an uncertainty analysis.

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Fatigue tests under reversed flexure have been conducted on samples of 7075-T6 Al-alloy with the application of electroless Ni-P deposits of thickness ranging from 5 to 50 μm after salt spray corrosion (100, 500 and 1000 hours). The corrosion damage of the coated and uncoated samples was determined through the measurement of the mass loss and surface corroded morphology. The mean microhardness of the high phosphorous (Hi-P) deposits in 5, 25 and 50 μm thickness were found to be 334, 457 and 606 Hv₅₀, and the mean surface roughness (Ra) were measured at 0.197, 0.217 and 0.223 μm for 5, 25 and 50 μm thickness, respectively. The salt spray tests revealed that the corrosion damage increases as the exposure time increases for the 5 μm coating. The corrosion damage literally stopped when the coating thickness was increased to 25 μm. The fatigue strength of the coated samples was found decrease slightly as the deposit thickness increases to 25 μm, whereas the reduction on the fatigue strength for the 50 μm deposit is significant. It has been observed that the reduction in the fatigue strength is less or to none for the thicker coating system. For the 5 μm Hi-P deposit sample, the fatigue crack initiation started at the surface corrosion pitting then extending to the substrate and onto failure, this phenomenon reduced the fatigue strength as compared to the uncoated samples. The fatigue strength is decreased slightly as the thickness increases to 25 μm and 50 μm. With or without corrosion damage, the fatigue crack initiation all started from the coating and extended to the substrate through the bonding between the coating and the substrate. Balancing between the need for the corrosion resistance and the fact on the fatigue strength reduction, the optimum coating thickness seems to be greater than 5 μm but less than 25 μm for the aerospace alloy 7075-T6 Al-alloy.

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The authors developed 3Y-PSZ/AISI 316L composites for the bearings of joint prostheses, which were then evaluated in terms of their mechanical properties, such as density, hardness, bending strength, fracture toughness and wear resistance, as well as corrosion resistance. The composites (AISI 316L contents were 0, 10, 20 and 30 vol%) were fabricated by spark plasma sintering. The composites consist of tetragonal zirconia and austenite stainless steel. The Vickers hardness and bi-axial bending strength of the composite decrease from 14.3 GPa to 8.93 GPa and 1585 MPa to 617 MPa, respectively, when the AISI 316L content is increased from 0 vol% to 30 vol%. Fracture toughness of the composite increased from 4.99 MPa·m^1/2 to 6.03 MPa·m^1/2. The composites showed improved wear resistance (3Y-PSZ; 3.08 × 10⁻¹⁰ mm²/N, 10 vol% composite; 2.11 × 10⁻¹⁰ mm²/N, 20 vol% composite; 0.28 × 10⁻¹⁰ mm²/N, 30 vol% composite; 0.00 × 10⁻¹⁰ mm²/N). The wear resistance of the 30 vol% composite was higher than conventional biometal and bioceramic (AISI 316L; 35.4 × 10⁻¹⁰ mm²/N, Co-28Cr-6Mo; 11.0 × 10⁻¹⁰ mm²/N, Al₂O₃; 0.30 × 10⁻¹⁰ mm²/N). The composites showed more than 3 times greater corrosion resistance than the monolithic AISI 316L in PBS(−) at 37°C. In particular, nickel ion release was lower than for AISI 316L. The corrosion resistance of 30 vol% composite during the wear test was more than 37 times higher than for AISI 316L. The 30 vol% composite was successfully toughened and showed higher resistance to wear and corrosion when used as bearing material for joint prostheses.

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In this paper, 5052H34 Al-Mg plates are joined by Friction Stir Welding (FSW) at various rotation speeds ranging from 2000 to 2700 min⁻¹ to explore the deterioration of tensile and vibration fracture resistance. An average grain size of 16 ± 1 μm could be observed in the stir zone (SZ) at all rotation speeds. The results of tensile and vibration tests which are done transversely in the stir zone verified that the FSW 5052-H34 specimens become significantly different from the base metal, and the deterioration pertains to the microstructural revolution and joining defects.
The best condition of FSW specimens for the test of vibration fracture resistance can be acquired when an optimal tool rotation speed (2400 min⁻¹) is selected to avoid microstructural defects. The deterioration of the material in this study can also be recognized in the existence of heat affected zone (HAZ). On the other hand, vibration fracture resistance can be significantly improved if the crack initiation and propagation through the stir zone of FSW are controlled. That is correlated with the formation of the fine grains through dynamic recrystallization in the vicinity of stir zone.

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Ti-based glassy alloy rods with diameters up to 5 mm were prepared for Ti_41.5Zr_2.5Hf₅Cu_42.5Ni_7.5Si₁ in a multi-component system of (Ti, Zr, Hf)-(Cu, Ni)-Si by conventional copper mold casting. The new mutli-component glassy alloy exhibits moderate thermal stability with a supercooled liquid region (ΔT_x) above 50 K. The glass transition temperature (T_g), crystallization temperature (T_x), melting temperature (T_x), liquidus temperature (T_l), and the reduced glass transition temperature (T_g/T_l) are 680 K, 730 K, 1143 K, 1199 K and 0.57, respectively. The cast glassy alloy exhibits compressive strength of 2080 MPa, tensile strength of 2040 MPa and Young's modulus of 100 GPa. The reason for the high glass-forming ability (GFA) of the Ti-based multi-component alloy is discussed on the basis of knowledge available for bulk glass formation.

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Magnetocaloric effects due to the itinerant-electron metamagnetic transition for La(Fe_0.90Si_0.10)₁₃ compounds promising as refrigerants are enhanced by a partial substitution of Ce for La. The values of the isothermal magnetic entropy change ΔS_m and the adiabatic temperature change ΔT_ad for La_1−zCe_z(Fe_0.90Si_0.10)₁₃ compound with z = 0.1 are −32 J/kg K and 12.8 K, respectively, just above the Curie temperature in the magnetic field change from 0 to 4 T. Such large magnetocaloric effects can also be obtained in the vicinity of room temperature by hydrogen absorption. Annealing at 1373 K for 20 days makes it possible to substitute up to z = 0.2.

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Mg₄Pd crystalline and amorphous alloys were prepared and X-ray diffraction patterns of these alloys were measured with synchrotron radiation using the large Debye-Scherrer camera installed at BL19B2 in SPring-8. The X-ray diffraction patterns have been successfully collected for the alloys. Using the X-ray diffraction pattern of the Mg₄Pd crystalline alloy, crystallization stages of the Mg₄Pd and Mg₉Pd amorphous alloys have been reviewed. As a result, the phase precipitated at the first crystallization stage of the Mg₄Pd amorphous alloy has been identified to be Mg₄Pd. In addition, it has been conjectured that the phase precipitated at the third crystallization stage of the Mg₉Pd amorphous alloy is Mg₄Pd, as well.

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