An in-house grazing X-ray reflection (GXR) apparatus has been newly built for studying the liquid surface, and the liquid-solid and liquid-liquid interfaces. This apparatus consists of a high flux rotating anode X-ray generator, pairs of slits for incident and diffracted beams, a channel-cut Ge 440 crystal monochromator and a double-axis diffractometer. This system was tested by measuring X-ray reflectivity profiles from free surface of water or mercury, and the water-mercury interface.

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The Monte Carlo method combined with the static variational method is applied to a computer simulation on the phase decomposition process when a precipitate in a bcc binary alloy is elastically harder than the matrix. The present study is compared with our previous results that were obtained for the case of the same elastic constant of the precipitates as that of the matrix in our previous report. We have adopted the Jonson-type potentials as the interaction between the constituent elements, and have used three kinds of interaction potentials between solute atoms.
We find an anisotropic structure in the alloy whose elastic constant of the precipitates is equivalent to the constant of the matrix. The alloy that has harder precipitates than the matrix shows an isotropic structure or a little anisotropic structure depending on the value of elastic constant of the precipitates.
We presume that the isotropic structure is yielded because of the larger contribution of the interfacial energy than the elastic strain energy. Evidently the total energy of the alloy with isotropic clusters is lower than that with anisotropic clusters for every potential used in the present simulation. Therefore we conclude that the formation of anisotropic clusters is not due to the shape of precipitates with the minimum elastic energy but due to the dynamical process of phase decomposition concerned with nonlinear many body effect.

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Effect of purity on static softening and grain growth taking place after dynamic recrystallization (DRX) was studied by means of interrupted compression tests and metallographic observations of polycrystalline copper specimens with three different purities of 99.9 (3N), 99.99 (4N) and 99.9999 (6N) mass percent. The fractional softening-annealing time (X-t) curves after dynamic recovery consist of two stages, followed by complete softening. In contrast, the softening curves for DRX matrices consist of three distinct stages accompanied with three plateaus, followed by incomplete softening (stages I, II and III). The X-t curves for DRX matrices of specimens 3N and 4NCu are almost the same, but clearly different from that for specimen 6NCu. The static softening for a DRX matrix of specimen 6NCu takes place one order of magnitude faster than that for specimen 3N or 4NCu and finally approaches X=1 after a long period of annealing time in stage III. The average rate of grain growth in stage III is always smaller than that for normal grain growth, although both the rates are controlled by grain boundary diffusion irrespective of purity of copper. This results from the stable existence of metadynamically recovered grains which have many-sided irregular shapes as well as high density dislocations. As these grains are metastable in thermodynamics, however, DRX matrices only for specimen 6NCu finally replace fully recrystallized ones, followed by the occurrence of normal grain growth.

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As a fundamental study for the oxygen-blowing copper smelting, the phase equilibrium between ferrite slag and copper matte was investigated at 1523 K under the partial pressures of SO₂ controlled at 10.1, 50.7 and 101.3 kPa, using a sulfur reservoir for controlling the partial pressure of S₂. An oxygen-sulfur potential diagram was constructed in relation to matte grade, and it was clarified that the ratio of (p_O2⁄p_S2) was constant against p_SO2 when the matte grade was specified. The solubilities of copper and sulfur in the slag and calcium in the matte as well as (%Fe³⁺/%Fe²⁺) in the slag were also determined in relation to matte grade. The solubilities of copper and sulfur were found to be independent of p_SO2 when the matte grade was specified and it was considered that this behavior was ascribable to the constancy of (p_O2⁄p_S2) against p_SO2. The solubility of sulfur decreased gradually with increasing matte grade. On the other hand, the solubility of copper represented the minimum at matte grade with about 72.5 mass%Cu, which was analyzed thermodynamically based on a concept of oxidic and sulfidic dissolutions of copper component in the slag.

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It has been known that the new donor ND1 whose deep-level transient spectroscopy (DLTS) peak appears at about 33 K can be generated in two-step heat treated (723 and 923 K) carbon-rich n-type CZ silicon. In this study, the annihilation process of the new donor ND1 is studied by a combination of electrical measurement, DLTS and Fourier transform infrared spectroscopy (FTIR). The results show that the ND1 is annihilated by annealing at temperatures above 1073 K. The size of the ND1 cluster is not the same, but distributes in a certain range. The ND1 loses its electrical activity by both decomposition and growth of the ND1 cluster during the annealing. Annealing at a temperature between 1073 and 1273 K would delay the ND1 annihilation by decomposition and enhance that by growth in the subsequent annealing at a higher temperature.

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This paper describes the effect of laser welding process on the fatigue crack propagation in SPCC-CQ1 cold rolled steel. The influences of weld speed and gap width of butt joint on fatigue crack growth rate are considered. Strength of the weld joints is evaluated by a tensile test, while fatigue properties are investigated by fatigue crack propagation test based on linear elastic fracture mechanics. From the results, the added wire filler material had positive effect on the fatigue properties. Increasing welding speed or gap width will improve the resistance to fatigue crack growth because of fast cooling rate and refined equiaxed microstructure in fusion zone. Also, the fatigue crack growth rate of fusion zone and heat affected zone are lower than that of base metal. Transgranular fracture is the typical fracture mechanism and many secondary cracks appear in the fusion zone.

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Compressive creep tests were carried out at 1100 K on Ti-53 mol%Al polycrystals up to high strain. It has been well recognized that the steady-state stage appears in region I, under high stresses, after the normal primary stage. It is revealed in this investigation that in regions II and III, under intermediate and low stresses, the steady-state stage also appears after the acceleration stage following minimum creep-rate. It becomes evident that the steady-state stage appears accompanied with bulging-type dynamic recrystallization under low stresses, when creep proceeds up to a large strain. Stress dependence of the steady-state creep-rate reveals that creep behavior in the steady-state stage is classified into two types, I and I′, although three types are recognized for the minimum creep-rate. The stress exponent in region I′ (for \dotε_s) is about 3.5 which is almost the same as in region III (for \dotε_m).

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