A reactor chamber was designed for the investigation on the basic physico-chemical processes of the preparation of ultrafine particles in a radio-frequency (rf) plasma. Ultratie iron particles with a statistical median size of about 10 nm (based on number) were prepared by passing pure iron powders through an rf plasma. The nature of these products was investigated by electron microscopy and X-ray diffraction analysis. Nucleation and growth mechanism were also considered. It was found that the growth process of the particles took place in a “fog” state and a Brownian collision-coalescence mechanism governed the process. The particles formed the morphology common to fcc metals, though the electron diffraction patterns showed no traces of the fcc form. This means that the particles solidified in the γ-phase and then transformed to α-phase. The particles with the size less than 60 nm could be transformed into single crystals of α-phase, but single crystals rarely existed when the particle size was larger than 100 nm.

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An electron microscopic study has been made of precipitation in an austenitic stainless steel, 16Cr–16Ni–0.8Nb–1.8Mo–0.06C. Attention has been focused on structural changes which take place during long ageing treatments, extended up to 14.4 Ms (4000 h). In addition to the well-known chromium rich M₂₃C₆ carbides, which appear, together with NbC, from the beginning of the precipitation treatment at 1073 K, a new plate-like morphology of M₂₃C₆ carbide precipitation was observed after long ageing treatments. These M₂₃C₆ carbide plates were formed on {110} planes in regions near pre-existing undissolved NbC particles and their edges were bounded by {111} planes of the fcc alloy matrix. It is suggested that this unexpected process might be favoured by the stresses produced around the undissolved NbC particles.

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Reactions between steam and metal sulfides such as Ag₂S, CaS, and ferrous sulfide were investigated in the temperature range 900–1100 K by monitoring the evolved hydrogen. These reactions are characterized by solid products and can be classified into three types, that is, metal, oxide, and sulfate, respectively. For the reaction of CaS or Ag₂S with steam, it was concluded that generation of H₂ is due to the oxidation of S²⁻ in the sulfide phase. In ferrous sulfide, the contribution of the oxidation of Fe²⁺ to the hydrogen evolution is of importance. Furthermore, it was confirmed that selective oxidation of Fe²⁺ or S²⁻ in the ferrous sulfide proceeds depending upon the extent of nonstoichiometry of ferrous sulfide. It is also shown that the addition of lime to ferrous sulfide results in a considerable increase in hydrogen concentration.

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The growth characteristics of martensites in thin foils of an Fe-4.1 mass%Mn-1.25 mass%C alloy have been investigated by means of transmission electron microscopy with a cooling stage. Thin foil martensites are formed instantly by cooling below M_s temperature as in bulk specimens. In the regions where the martensites are small and/or less affected from other neighboring martensites, they are surrounded by a sharp planar and diffuse little curved interfaces, the former being consistent with a {225} plane which has been known as the habit plane for bulk martensites. The martensite crystals grow upon further cooling and/or irradiation with electron beams, only one interface advancing. Upon growth, planar or curved interface is sometimes curved or straighten, respectively, depending on stress or strain field from neighboring martensites. However, both originally and subsequently curved interfaces are finally straighten when they reach or join to the interface of other martensites, and thus the tip of thin foil martensites comes to be formed with two straight interfaces; {225} habit plane and another {225} plane. It is considered from these observations that thin foil ferrous martensites nucleate to satisfy the invariant plane strain condition as in bulk specimens, although they take a curved or irregular interface during the growth.

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In order to find a sulfide solid electrolyte with high ionic conductivity, the electrical conductivities of alkaline earth sulfides and CaS doped with a rare earth sulfide or a titanium group sulfide were measured by the ac bridge-complex impedance plot method at 1073–1673 K. From the dependence of the conductivity on sulfur partial pressure, the ionic conduction of these sulfides was evaluated. MgS, CaS and SrS showed ionic conduction at low sulfur partial pressure, but their conductivities were too low as a solid electrolyte. BaS and CaS doped with a rare earth sulfide exhibited high conductivity due to the electronic conduction. CaS doped with a titanium group sulfide showed ionic conduction except at low sulfur pressure. CaS doped with TiS₂ showed high ionic conductivity. Among these sulfides CaS doped with TiS₂ was found to be the most suitable solid electrolyte for determination of sulfur in liquid iron.

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Iron rich β precipitates were observed in single crystals of unalloyed T40 titanium. It is inferred that the solubility of Iron in α is smaller than 600 ppm. An fct phase, with parameters a=0.432 nm and c=0.467 nm was identified at the α-β interfaces; it was identical to the interface phase reported in several α-β alloys. We show that, in T40, this phase is, most likely, a titanium hydride due to the preparation of the thin foils.

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A small amount of the simulated oxide coated cathode metaloxide interface layer formed between (Ba, Sr, Ca) CO₃ powder and Ni–W–Zr ternary alloy base metal was separated from a base metal using anodic dissolution. Composition was studied by quantitative elemental analysis. Nickel was determined by flame atomic absorption spectrometry. Tungsten and zirconium were determined by spectrophotometry. The results show that the interface layer contains a large quantity of nickel and 10–20% zirconium oxide.

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Winning of high purity iron was carried out from red mud in aluminum refinery and iron concentrated tailing in copper smelting by leaching with hydrochloric acid and anion exchange separation. The iron obtained was further purified by floating zone-melting in vacuum. The purity of the iron refined was examined by measuring RRR_H values and by analytical methods such as activation analysis and spark source mass spectroscopic analysis. It is confirmed that the iron purified is very pure and nearly corresponds to the commercial high purity iron such as Johnson-Matthey iron with nominal purity of 99.99%. In order to know the chemical composition of the residue after leaching, PIXE method was applied.

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Diffusion coefficients of hydrogen and deuterium in high purity iron were measured by an electrochemical alternating current method at temperatures between 222 and 322 K . In this method, the diffusion coefficient can be evaluated from the frequency response of the phase difference between an anodic permeation current and a cathodic charging current by eliminating the surface effect from the permeation process. The diffusion coefficient of hydrogen in iron is proposed to be D^H(m²⁄s)=4.90×10⁻⁸exp(−4200(J⁄mol)⁄RT). The activation energies of diffusion for the two hydrogen isotopes were equal at 4200 J/mol. And the isotope ratio of pre-exponential factors, D₀^H⁄D₀^D, was determined to be 1.24, which was a little smaller than the classical ratio 1.41. At low temperatures, the trapping effect by lattice imperfections was observed, and it was more remarkable for deuterium than for hydrogen.

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