One-directional solidification of Ho₁Ba₂Cu₃ oxide superconducting filaments produced by suspension spinning was studied to enhance the J_c of the filament. The filaments were heated the above solidus temperature and then one directionally solidified in a tube furnace. The effects of various processing parameters on the structure and superconducting properties of the solidified filament were discussed. High J_c values of 2500 and 2100×10⁴ A/m² at 77 K and 0 T were attained for the filament solidified at a removing speed of 0.083 mm/s with and without sintering, respectively. The surface of the filament was covered with fine needle-like crystalline networks of the nonsuperconducting phase of less than 10 vol.%, and bulk superconducting crystals were packed densely in the core of the filament. However, any preferred orientation of the crystals was not detected.

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X-ray diffraction, differential scanning calorimetry and electrical resistivity measurements have been performed on sputter-deposited T_1−xPd_x alloys. An amorphous phase is obtained for 0.3<x<0.5 on water-cooled substrates and for 0.2<x<0.6 on liquid-nitrogen-cooled substrates, while the bcc phase (β-Ti) and the fcc phase are obtained for both Ti-rich and Pd-rich concentration regions. The crystallization temperature of amorphous alloys is about 700 K, being insensitive to x. With increasing x, the residual resistivity increases for x<0.2 (in the bcc phase), reveals a maximum of about 3 μΩ·m for 0.3<x<0.5 (in the amorphous phase) and decreases for x>0.7 (in the fcc phase). With increasing temperature, the resistivity increases in the bcc alloys with x<0.1 and the fcc alloys with x>0.8, while it decreases in the bcc alloys with x>0.1 and all of the amorphous alloys.

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Cd or Zn fine crystals having the shape of whiskers or polyhedrons were grown by a physical vapor deposition method. Their growth mechanism was VLS (Vapor-Liquid-Solid) growth. The nucleation of the crystal growth occurred in the eutectic alloy droplet (homogeneous nucleation) and not at the interface between the droplet and a glass substrate (heterogeneous nucleation). The purpose of the present study is to explain this reason.
In order to decide the nucleation type (homogeneous or heterogeneous), we introduced the parameter Y defined as Y=γ_SG−(γ_LG+γ_SL), where γ_SG, γ_LG and γ_SL are the interfacial tension between the crystal and the glass, between the liquid and the glass, and between the crystal and the liquid, respectively. When Y>0, the nucleation type is homogeneous, and when Y<0, it is heterogeneous.
In the case of VLS-grown Cd or Zn crystals, it was found from the data on the surface tension that the parameter Y was positive. Therefore, it was concluded that the nucleation type of the Cd or Zn crystals was homogeneous.

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Thermal desorption spectra (TDS) of hydrogen from Ni–Zr alloy glasses are studied experimentally and theoretically. The spectra manifest composite peaks which change systematically with the hydrogen content and alloy composition, Defining a site energy distribution function, N(E), for the dissolved hydrogen atoms and employing a surface recombination model for the desorption kinetics, TDS spectra are calculated and compared with the experiment. The simulated N(E) function has a few Gaussian peaks, and they are attributed to the hydrogen occupancy in quasitetrahedral interstices with different site energies in these glasses.

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The scheme previously proposed by the authors on the basis of the Taylor model to deal with the deformation of polycrystals caused by the stress induced martensitic transformation (SIM) has been futher extended to describe the recovery stress associated with the reverse transformation upon unloading. According to this scheme, the “modified” Taylor factor M′ has been calculated as a function of grain orientation for the cases of tensile and compressive deformation in shape memory alloys such as CuZnAl, CuAlNi and TiNi. The results demonstrated the difference in the plastic anisotropy for SIM of grains under the polycrystalline constraint from that of isolated crystallites. The strain hardening due to the internal stresses caused by the grain orientation dependence of volume change has been shown to be insignificant in these alloys. General discussion has been given to the yield stress, recovery stress, pseudoelastic hysteresis, recovery strain, ductility, and strain hardening of the shape memory alloys, in relation to the magnitude and orientation dependence of M′.

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Oxidation behavior of a TiN_0.74 coupon was studied in a temperature range 1100 to 1300 K in a flow of purified oxygen at atmospheric pressure. The thermogravimetry showed two-stage parabolic laws with the rate constant of the first stage, Kp₁, being slightly smaller than that of the second stage, Kp₂. They are expressed in the following equations in kg²·m⁻⁴·s⁻¹, with activation energies in J·mol⁻¹.
Kp₁=79exp(−183000⁄RT)
Kp₂=33.6exp(−171000⁄RT)
During the initial periods the oxide scale consists of a dense outer rutile layer and an inner rutile layer containing micropores randomly distributed. However, as the oxidation proceeds, a multi-layered structure develops in the inner layer by the repeated evolution of micropores aligned in lines almost parallel to the substrate. After a very long oxidation period, however, the layered structure becomes very vague because of sintering of the oxide. The growth of the inner layer showed a transition from parabolic to linear manner. These observations are explained in terms of the change in the scale structure which was attributable to the saturation of the substrate with nitrogen liberated by the consumption of titanium.

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The behavior of carbon deposition on as-polished or pre-oxidized Fe–Ti alloys containing 0–2.11 mass% Ti in a 10%CH₄–H₂ mixture at 1203 K was studied by metallography and thermogravimetry. Titanium retarded carburization and carbon deposition by changing the microstructure of the alloys from austenite to ferrite in which the solubility limit of graphite is much lower and by forming a stabler carbide (TiC) than Fe₃C. In particular, carbon deposition on as-polished alloys containing 0.67 mass% Ti or more was markedly depressed because of the formation of TiO₂ on the surface despite the carburizing atmosphere. Under this condition, TiO₂ may have formed by the reaction of titanium in the alloys with small amounts of oxidizing gases such as O₂ and H₂O present in the atmosphere. On oxidation in air, Fe₂O₃, Fe₃O₄, and FeO formed on iron and a small addition of titanium (0.09 mass% Ti) retarded the formation of FeO and a further addition of titanium up to 2.11 mass% caused the formation of FeO·TiO₂ and TiO₂ besides Fe₂O₃ and Fe₃O₄. The exposure of the alloys containing 0.67 mass% Ti or less to the 10%CH₄–H₂ mixture after the oxidation in air led to a sudden mass loss in the early stage and then a rapid mass gain. This mass change is primarily ascribed to mass loss by reduction of iron oxides and to mass gain by carbon deposition. The rapid mass gain by carbon deposition is probably due to the formation of active iron by reduction of iron oxides and to the increase in the reaction area by spallation of the scale; the active iron formed may promote the direct deposition of filmy carbon on the surface and filamentous carbon deposition through Fe₃C formation and decomposition. Carbon deposition on the alloys containing 1.40 mass% Ti or more, however, was considerably depressed because TiO₂ formed during the oxidation remained even during carburization, although the amounts of carbon deposition increased compared with those on the as-polished alloys owing to the coexistence of reducible iron oxides.

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The recovery of precious metals such as Au, Ag, Pt and Pd from complex sulfide ores and the by-products of electrolysis of copper crude metal containing precious metals, are treated with pyrometallurgical processes. The refinery recovers Au, Ag, Pt, Se and Pd as by-products of copper refining processes, and manufactures copper powder, foil, wire bars and chemicals for plating. However, pyrometallurgical processes are generally accompanied by leberations of sulfur dioxide and metal containing particles into atmosphere. They are undesirable as a source for serious environmental problems. In an effort to overcome these difficulties, an oxidative leaching treatment for Cu-anode slime in nitric acid solution containing sodium chloride was investigated. In the present study, the acid leaching reaction and the oxidative leaching behavior of Cu-anode slime in a nitric acid solution containing sodium chloride are evaluted from both thermodynamic considerations and the results of an experimental study of leaching rates, which are based on the stoichiometry of the leaching reaction and the X-ray diffraction analysis of the leaching products.

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The reaction of cubic ZrO₂, with La(Co_1−xNi_x)O₃ was investigated by hot pressing at 1573 K. The reaction can been seen for all of x. The compositions of the reacted areas were estimated as La₂Zr₂O₇, La₂Zr(Ni_0.6Co_0.4)O₆ and La₂ZrNiO₆ for x=0, 0.4 and 1, respectively. The width of the reacted area decreased with increasing Ni fraction. The sintering of samples with compositions of the reacted areas mentioned above was made to investigate the crystal structures, electric resistivities and thermal expansion coefficients of the reacted compounds. The thermal expansion coefficients of the reacted compounds were always intermediate between those of cubic ZrO₂ and La(Co_1−xNi_x)O₃. The electric resistivity of La₂Zr₂O₇ was an extremely high order of 10³ Ω·m even at the temperature of 1273 K. The substitution of Ni or Co for the Zr site decreases the electric resistivity and becomes the order of 10⁻¹ Ω·m at the temperature of 1273 K. The electrode materials of cubic ZrO₂ fuel cells are also discussed on the basis of the present experimental results.

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