This paper describes the light-microscopic observations of polystyrene latexes with spherical particles of two different diameters, d and 1.4–1.9d. Polystyrene latexes are available for simulating real structures in intermetallic compounds. An amorphous state appeared for a few hours after stirring or vibrating the latexes, and subsequently, the Laves phase structure nucleated and grew by the Brownian motion of the particles whose diameters were d and 1.4–1.7d. The structures of the observed Laves phase were classified into the MgCu₂ and the MgZn₂ types, containing such lattice defects as grain boundaries, dislocations, vacancies or mis-arranged particles.

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Polystyrene latexes with particles of diameters 250 and 500 nm are observed under a metallurgical microscope. The crystal structures of the RCo₅ and the R₂Co₁₇ types appear stably through the thermal motion of particles, where R means rare earth element. Various defects such as diffuse interfaces, dislocations, point defects, amorphous structures, or segregations of the large and the small particles are distinctly observed in these structures. Polystyrene latexes are found to be useful to study on an atomic scale the crystal structures and their kinetic behavior of intermetallic compounds of the R–Co system.

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The martensitic transformation in an Fe-30.0Ni-3.8Ti (mass%) alloy ausaged at 973 K for various periods has been examined by means of optical as well as transmission electron microscopy, electron as well as X-ray diffraction and electrical resistivity-temperature measurements. While the martensites in the unaged specimens were lenticular in shape as those in Fe–Ni binary alloys, those in the specimens ausaged for longer periods were of thin plate to a great extent, when formed at temperatures near the M_s, though the M_s temperature became considerably higher than that of the unaged specimens. Some of the thin plate martensites grew in the sidewise as well as the lengthwise directions and eventually became lenticular upon cooling to lower sub-zero temperature, the newly produced martensites during the sub-zero cooling being also lenticular. In addition, the thin plate martensites were so unique that twinned regions were hardly observed inside. The crystal structure of the martensite was tetragonal with c⁄a=1.02 in the unaged state. The tetragonality rapidly increased a little to 1.03 after short ausageings, but it diminished to almost unity after prolonged ausageings.
The morphological change of martensites associated with ausageing and sub-zero cooling was discussed together with the peculiar austenite stabilization phenomenon previously reported.

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Any stress relaxation curve for polycrystalline molybdenum, obtained from stress relaxation tests by a monotonic loading mode and plotted as log σ vs log \dotε, can be superposed on each other by scaling and forms a unique master curve. The effects of such various factors as grain size (20–1500 μm), imposed strain rate (10⁻⁵−3×10⁻⁴ s⁻¹), impurities (commercial pure molybdenum and Mo–Co alloy) and temperature (292–550 K) on the shape of the master curve are investigated. A deeper understanding of the characteristics and the physical meaning of the master curve have been acquired by investigating experimental results.
The primary shapes of master curves are not affected by the factors of grain size and imposed strain rate, and the master curves can also be superposed on each other by scaling. Subsequently, the stress-strain rate scaling parameter \barm [=(δ ln \dotε⁄δ ln σ)_ν] obtained as areciprocal of the slope on scaling of master curves coincides with m of forming each master curve. On the other hand, the master curves obtained on materials of different purities or at different temperatures cannot be superposed on each other because of their different shapes. It is concluded from the results that the different shapes of master curves may be attributed to the change in short range obstacle profiles for dislocation movement due to impurities and to the change in the effective stress due to temperature.

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The corrosion behavior of Fe–5, −13 and −25%Cr alloys in hydrogen chloride gas containing 0–75 vol% oxygen at temperatures between 573 and 923 K was investigated by means of a thermogravimetric technique and by measuring the mass loss and X-ray analysis of the scales. In hydrogen chloride gas, the corrosion rate was determined by the formation and sublimation of divalent chlorides of iron and chromium. Addition of chromium to iron effectively decreases the corrosion rate at temperatures lower than 673 K. The scale formation rate increased with increasing chromium content of the alloys at 673 K or higher temperatures, and only FeC₂ selectively sublimed up to 873 K. Addition of oxygen to hydrogen chloride gas effectively suppressed corrosion of Fe–Cr alloys containing 13% or more chromium at relatively low temperatures due to formation of a protective corundum-type oxide scale. The temperature range for the protective scale formation was raised with increasing alloy chromium content and oxygen content of the gas mixture. Further rise in temperature accelerated corrosion due to sublimation of FeCl₃ and CrCl₃ as a result of oxychlorination.

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The relations among the quantities participating in surface formation have been studied on the basis of the following assumptions: (i) There is an analogy between surface formation and vaporization. (ii) The surface tension as a function of temperature is given by the equation, γ∝(1−T⁄T_c)^B, where T_c is the critical temperature and B is the exponent.
Based on the above assumptions the following expressions for the relations among surface quantities are determined by statistical analysis of experimental data: (1) The surface entropy is given by the equation, s≈0.1S, where S the specific vaporization entropy in J/(m²·K), defined as the vaporization entropy per unit area of the monatomic layer in bulk. (2) The surface tension is given by the equation, γ=1.536×10⁴ S^1.62, where γ is the surface tension in N/m. (3) The surface tension is given by the equation, γ=0.152+4.61×10⁻⁴ E_v⁄V^2⁄3, where E_v, is the formation energy of a vacancy in eV and V is the atomic volume in m³.

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The activity coefficients of oxygen, γ_O, in liquid Ag–Bi and Ag–Tl alloys at 1273 K have been measured over the entire composition range utilizing a modified coulometric titration method with the electrochemical cell: O in liquid Ag–Bi or Ag–Tl alloys/ZrO₂(+CaO)/Air, Pt. The measured ln γ_O values for both systems, plotted in terms of alloy composition, lie on upwardly concave curves. The data were found to be somewhat larger than those calculated from Jacob and Alcock’s quasi-chemical equation. This trend appears to be in line with the observation for the Ag–Pb–O system.

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Several experiments were carried out to study the formation mechanism of inverse segregation in Al–Cu alloy ingots.
Al-4 mass%Cu alloy ingots solidified horizontally in a stainless steel mold showed only a columnar zone and inverse segregation. However, an Al-14 mass%Cu alloy exhibited either only equiaxed crystals or a columnar-equiaxed transition structure depending on the cooling temperature. No clear inverse segregation occurred in these ingots. It is considered that equiaxed crystals moved with the flow of the melt, and these crystals were irregularly distributed when it solidified.
All ingots solidified from the bottom or from the molten surface in a stainless steel mold or a graphite mold showed inverse segregation. In particular, an equiaxed zone in the Al-14 mass%Cu alloy solidified from the molten surface in the graphite mold had an extremely low Cu concentration.
On a chill face of ingots decanted during the unidirectional solidification, the Cu concentration was always higher than the mean concentration of the alloy. This suggests that the solute Cu was already concentrated near the chill face at the initial stage of solidification. It is considered that the solute was trapped among the crystals of the stable solid shell formed on the mold wall.

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