A (111) surface of copper crystal was etched anodically at a constant potential of 0, 20 and 40 mV vs SHE in an electrolyte containing 5 kmol·m⁻³ NaCl, 0.25 kmol·m⁻³ NaBr and 10⁻⁴ kmol·m⁻³ CuCl, and the dissolution of dislocation etch pits was investigated by the use of optical and interference microscopes. The etch pits formed a slightly rounded triangular pyramid. The width and depth of these etch pits increased non-linearly at the early stage of etching, and then increased linearly with an increase of etching time, while the side slope decreased with increasing etching time and reached asymptotically a constant value. On the other hand, the anodic current density decayed initially to a minimum value and then increased slowly corresponding to the steady growth of the etch pit size. It was shown that the time dependence of anodic current density could be semiquantitatively explained in relation to the dissolution rates of dislocation etch pits.

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A general form of Fourier expression for the two-dimensional non-linear diffusion equation containing the gradient energy term is proposed, and computer-simulations in some supersaturated solid solutions are derived on the basis of the Fourier expression. The phase-decompositions proceed to form the mottled structure in the case of elastically isotropic alloy, but to form the [100] modulated structure for an anisotropic case. The microstructure simulated here explain well morphologies of actual alloys spinodally produced, hence the diffusion-behaviors based upon the 2-D Fourier expression seem to be essential for the basic understanding of the formation of the microstructure.

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An iron single crystal with the bulk sulfur concentration adjusted between 23 and 66 mass ppm was heated at 1023 K in vacuum, and the segregation rate of sulfur on the (100) surface was measured with good reproducibility by using AES. The result was compared with a theoretical equation.
Because the equilibrium concentration of sulfur on the surface was constant, unaffected by the bulk sulfur concentration and annealing temperature, the number of the surface sites on which sulfur could segregate was assumed to be constant. Assuming further that the segregation rate is proportional to the number of vacant sites on the surface and the bulk concentration of the segregant beneath the surface, a theoretical equation of the segregation rate has been derived. This equation shows that at an early stage of segregation the concentration on the surface increases in proportion to the annealing time, and that the segregation rate is proportional to the bulk concentration and independent of the diffusion coefficient of the segregant.
From the experiments, the concentration of sulfur on the surface was observed to increase in proportion to the annealing time and then reached a constant value. The segregation rate became greater as the bulk sulfur concentration increased. This tendency coincides well with that of the theoretical equation.
A concentration profile of the segregant near the surface influenced the segregation rate at the first stage. Therefore, in order to observe the segregation behavior with good reproducibility, it was necessary prior to measurements to sufficiently anneal the sample at a measuring temperature and sputter the surface by argon ions until the concentration on the surface became equal to the bulk concentration.

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Modified coulometric titration on the electrochemical cell: O in Tl–Te melts/ZrO₂(+CaO)/Air, Pt, was performed to determine the activity coefficient of oxygen, γo, in Tl–Te melts at 1073 and 1223 K as a function of solvent composition.
The γo value for molten Tl is lowered by slight addition of tellurium and then abruptly increased around N_Te=0.333. The ln γo vs composition curve exhibits a W-shape. The enthalpy and entropy values for oxygen dissolution were found to change discontinuously with composition of Tl–Te melts around N_Te=0.333. The experimental results were qualitatively interpreted in terms of a pseudobinary model. The data were also compared and discussed with values calculated using several solution models.

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The activity coefficients of oxygen, γo, in liquid Cu–In and Cu–Sn alloys at 1373 K have been measured over the entire composition range utilizing a modified coulometric titration method with the electrochemical cell: O in liquid Cu–In or Cu–Sn alloys/ZrO₂(+CaO)/Air, Pt. The measured In γo values, plotted in terms of indium or tin mole fraction, lie on a S-shaped curve, as predicted by Jacob and Alcock’s quasi-chemical equation. The present results for Cu–In alloys were significantly different from published values, while the results for Cu–Sn alloys were in reasonable agreement with reliable published values. The interaction parameters of indium and tin on oxygen in liquid copper were evaluated from the present data for the dilute alloys to be ε₀^(In)=−8.9 and ε₀^(Sn)=−2.8 at 1373 K, respectively.

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The isothermal oxidation behavior of Ni–15Cr sintered alloys with 1.0 mass% dispersion of various rare earth oxides, Y₂O₃, La₂O₃, CeO₂, Sm₂O₃, Eu₂O₃ and Gd₂O₃, was studied in air at 1473 and 1523 K. The dispersion of La₂O₃, Sm₂O₃ and Gd₂O₃ greatly reduced the oxidation rate; whereas, the dispersion of CeO₂ and Eu₂O₃ significantly increased the oxidation rate. The spalling of the scale was also dependent on the type of the dispersoid. The dispersion of La₂O₃, Sm₂O₃ and Gd₂O₃ greatly suppressed the spalling of the scale. The dispersion of Y₂O₃, CeO₂ and Eu₂O₃ also suppressed the spalling of the scale, but the effect of these oxides was far less than that of La₂O₃, Sm₂O₃ and Gd₂O₃. The scale formed on the Ni–15Cr alloy without dispersoid consisted of an outer NiO scale and an inner Cr₂O₃ scale; whereas a single layered Cr₂O₃ scale without an outer NiO scale was maintained on the alloys with dispersion of rare earth oxides, even CeO₂ and Eu₂O₃. However, the thickness of the Cr₂O₃ scale markedly increased at locations where the presence of Ce and Eu was detected by EPMA. La, Sm, Gd and Y were also detected in the Cr₂O₃ scale, but the thin Cr₂O₃ scale was maintained stably on the alloys with dispersion of these oxides.
The temperature and oxygen pressure dependences of the electrical conductivity of Cr₂O₃ doped with 1.0 mass% of rare earth oxides described above were measured at near atmospheric oxygen pressures in the temperature range from 773 to 1473 K. The introduction of these rare earth oxides changed the temperature and oxygen pressure dependences of the electrical conductivity of Cr₂O₃. These results suggested that the rare earth oxides induced into the scale might change the mechanism of the scale growth, but further detailed research is required before concluding whether or not the apparent dependence of the oxidation behavior of the Ni–15Cr sintered alloy on the kind of the dispersed rare earth oxides is due to the doping effect of the rare earth oxides on the defect structure of the Cr₂O₃ scale.

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Three-dimensional observations were made on the sizes and shapes of plastic zones formed around fatigue cracks in an Fe-3%Si alloy by means of the etch-pit method. Main results obtained are as follows:
(1) The shape and size of a plastic zone observed on the specimen surface are different from those in the interior, reflecting the change in the mode of deformation from “plane-stress” at the surface to “plane-strain” in the interior.
(2) The relationship experimentally obtained among plastic zone size, crack length and stress amplitude is predicted well by B–C–S model modified for fatigue cracks by taking the expedient cyclic yield stress into account.
(3) The stress state near the tip of a fatigue crack is assessed from measurements of the size of plastic zone on the specimen surface.

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The structure dependence of the 673 K embrittlement of ferritic spheroidal graphite cast iron with a constant graphite volume fraction and with various ones was investigated. Experimental results show that the fracture strain at room temperature and 473 K tends to increase as the structure size increases. At 673 K, the ductility tends to decrease extremely by the onset of intergranular (I.G.) fracture, as the structure size increases, but only the specimen of the smallest structure shows the ductile fracture without I.G. fracture. I.G. fracture becomes easier to occur, accompanied with the ductility decrease at 673 K, as the carbon content or the graphite volume fraction decreased. The suppressible effect of graphite nodules on the embrittlement due to I.G. fracture or cleavage fracture was considered. It was deduced that a larger triaxiality built at the matrix of a lower carbon content of ferritic spheroidal graphite cast iron leads to more embrittlement.

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