The atomic scale structure of the 0.9 μm thick amorphous Ge film on the Si single crystal substrate was determined by Mo Kα radiation with the Seemann-Bohlin arrangement with a small angle of incidence. Some difficulties of the quantitative analysis of the thin film were pointed out and our solutions were presented. At the same time, a new method has been proposed, by applying the anomalous dispersion effect of the constituent element of the film. The effective difference of the intensity profiles in this method estimated by the calculation was actually observed in the experiment at Photon Factory, National Laboratory for High Energy Physics, Tsukuba.

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The crystallographic aspects of the 4FeO→Fe₃O₄+Fe eutectoid decomposition have been examined by means of transmission electron microscopy. The eutectoid decomposition product exhibits a “pearlite-like” structure comprising α-Fe and Fe₃O₄ lamellae. Two α-Fe/Fe₃O₄ orientation relationships were observed, and they are those of the Bain and the inverse Nishiyama-Wassermann types, the former showing the well-defined (100)_α−Fe//(100)_Fe3O4 habit plane. The formation of these two orientation relationships arises probably from the epitaxial nucleation of α-Fe on the surface of a Fe₃O₄ particle.

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Ordered structures formed in Al–Li alloys during the decomposition were investigated by means of high resolution electron microscopy. Image calculations were also performed to interpret the obtained images.
In the initial stage of decomposition (323 K, 86.4 ks), extremely fine domains which had already an ordered structure of the L1₂-type were formed densely. The domains were separated by the vague and complicated boundary areas with incompletely ordered structure. In the proceeded stage of decomposition (473 K, 86.4 ks), spherical δ′ particles were formed and the atomic arrangement of a L1₂-type ordered structure was clearly observed within δ′ particles. The δ′/matrix interfaces were very clear and have a step-like morphology. It appeared that small segments with locally ordered structure were formed in the matrix during the electron microscope observation. Image calculations for the Al–Li alloys proved that atom sites were revealed as bright contrast dots under the proper defocus conditions, and that the image contrast was not changed drastically with the total specimen thickness at least up to ∼40 nm and depth of the ordered region. This is useful in discussing the formtion mechanism and spatial distribution of ordered domains in this alloy by using high resolution electron micrographs.

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In order to investigate the effect of environmental factors such as the corrosive species and temperature on the creep rupture properties of a nickel-base superalloy subjected to hot corrosion, creep rupture tests have been performed of Inconel 751 specimens with and without coating of different compositions of Na₂SO₄–NaCl salt mixtures in a temperature range between 1023 and 1173 K. The effect of hot corrosive environment on the creep rupture strength and the rupture behavior was found to differ considerably, depending on temperature and salt composition. Adding only a small amount of NaCl to the coating salts results in the marked degradation of the creep rupture strength along with the completely altered rupture behavior as compared with the case in air, in which the stress-enhanced preferential intergranular penetration of sulfides, oxides, and occasionally chlorides cause directly a premature intergranular fracture in a brittle manner prior to the formation of creep-induced internal grain boundary cracks. In particular, the detrimental effect of NaCl bearing environment is more pronounced in the lower temperature region below about 1073 K, even if it is lower than the melting point of salt, where chromium oxy-chlorides play the most important role in the intergranular attack behavior. However, an aggressive intergranular attack associated with the oxy-chloride formation tends to decline with increasing temperature because of higher volatility of oxy-chlorides as well as NaCl. In the higher temperature region above about 1073 K, an intergranular attack proceeds mainly by a successive sulfidation-oxidation process, while NaCl appears to play a catalytic action to promote the Na₂SO₄-induced aggressive attack. Increasing the temperature to about 1173 K results in the rather mitigated degradation of corrosion rupture properties along with the rupture behavior essentially similar to that in air because of the oxidation-dominating intergranular attack.

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This study was performed to obtain the concentration of defects and the activities of components in wustite doped with MeO(Me: Ca, Sr and Ba). The composition as FeO–Fe_2⁄3O–MeO for wustite in equilibrium with CO–CO₂ gas mixtures of P_CO2⁄P_CO=30⁄70, 50/50 and 60/40 at temperatures of 1273, 1373 and 1473 K, was determined by an analytical method utilizing the weight loss during reduction. The concentration of cation vacancies (V″_Fe) is estimated as one-third of the mole fraction of Fe_2⁄3O. The value of (V″_Fe) increases with an increase in the amount of MeO and in the ionic radius of Me except for the higher concentrations of CaO. The increase in the value of (V″_Fe) may be interpreted qualitatively by considering that the strain generated due to the difference in radius in the substitutional dissolution of MeO can be relieved by the formation of an association [M_Fe^XV″_Fe]. Furthermore, the activities of FeO and MeO were estimated by Schuhmann’s method from the oxygen pressure contours for wustite doped with CaO at 1273 K.

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Activity of calcium in Ca–Al alloys (X_Ca<0.38) was determined by the Knudsen effusion technique. Activity of aluminium in Ca-rich alloys (X_Ca>0.44) was calculated from the measured distribution coefficient for aluminium between the alloy and a thin foil of pure iron, using data for the Fe–Al system reported in the literature. By combining the results of Knudsen effusion and distribution studies with the Gibbs-Duhem relation, activities of both components and integral Gibbs energy of mixing for the complete composition range have been obtained at 1373 K. The concentration-concentration structure factor of Bhatia and Thornton at zero wave vector has been computed from the thermodynamic data. The mean square thermal fluctuation in composition exhibits a minimum for the Ca–Al system at X_Ca=0.26, suggesting the presence of a strong complex. The thermodynamic properties of the liquid alloy can be described by the associated solution model, with Al₂Ca as the predominant complex. The thermodynamic properties computed on the mole fraction basis are more compatible with experimental data than those based on volume fraction.

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An amount of 100 mg of nickel or cobalt sulfide was put in a slender alumina tube of 3 mm ID and 25 mm length and oxidized at 1473 K in a mixed O₂–Ar gas stream. Sulfur atomic fraction, x_s, was 0.30 to 0.40 for nickel sulfide and 0.400 to 0.446 for cobalt sulfide. When the x_s was lower, the NiO or CoO layer was formed on the melt surface without the evolution of SO₂ gas and the growth rate of the oxide layer was controlled initially by gas diffusion and subsequently by cation diffusion through the oxide layer. When the x_s was higher, the desulfurization took place which resulted in lowering of sulfur potential of the melt. When the p_SO2 in equilibrium with the melt and the oxide becomes lower than the atmospheric pressure, the formation of oxide starts to occur. The x_s-value at the transition from desulfurization to the oxide formation was 0.30 to 0.33 for nickel sulfide and 0.41 to 0.43 for cobalt sulfide.

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The surface of extruded material and the corresponding bearing surface in extrusion were directly observed by using the split-type die whose bearing can be easily replaced. The mechanism of surface roughness formation was schematized and examined, taking the effects of composition and finishing conditions of the bearing surface into consideration. As for the usual Al–Mg–Si–type 6063 alloys, the effects of the precipitates including Mg₂Si and Al–Si–Fe compounds on the surface roughness were also investigated. Thus, the following conclusions were obtained.
(1) As the bearing area increases, the extrusion pressure increases and the extruded-material surface becomes coarser. If the bearing is edge-like and its length is zero, however, the chain-line adhesion appeared on the bearing surface and therefore the state of the product surface becomes worse.
(2) When the extrusion temperature is high, the adhesion on the bearing surface shows plastic flow in the extruding direction and forms extremely rough stripes, and the product surface becomes rough.
(3) On the bearing surface ground vertically to the extruding direction, the ground grooves are filled with the adhesion material and the bearing surface becomes smooth, giving rise to a better surface condition of the extruded material. On the contrary, the ridged stripe of adhesion grows on the bearing surface which was ground in parallel with the extruding direction, and the resulting product surface becomes rough. The buffed bearing surface shows the spot-like poor adhesion which makes the product surface rough.
(4) When the nitrided SKD61 or WC-type sintered alloy (G₂), which have a weak affinity for the extruded material, is employed for the bearing surface, it is covered with a thin film consisting mainly of Al–Mg or of Al–Fe–Mg compounds and the extruded material with an improved surface can be produced.
(5) If the buffed SKD or buffed-and-salt-coaked VC, which have a strong affinity for the extruded material, is adopted for the bearing surface, the stripe of adhesion consisting mainly of Al, Fe and Si spread in parallel with the extruding direction, and the Al–Fe–Si compounds segregate in a high concentration from the die-surface corner to the bearing surface. In this case, the product surface becomes rough.
(6) As for the 6063 alloy for the general-purpose aluminum sashes, it is essential that Mg₂Si particles should not precipitate but disperse uniformly. When both Fe and Si are added, the product surface is rough.

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The relations between the order-disorder transformation and the permanent magnet properties of iron-platinum alloys have been investigated. The results show that the water-quenched alloy of γ single phase exhibits the typical soft magnetic properties. On aging at temperatures between about 770 and 870 K, the γ single phase transforms into a mixture of γ and γ₁ phases, whose magnetization is not easily saturated for the high crystal magnetic anisotropy of the γ₁ phase and the coercivity shows a low value. On aging at 903 K, the alloy of the γ₁ single phase which gives rise to broad diffraction lines exhibits the highest value of H_c=135 kA·m⁻¹. The ordering of the γ₁ phase is advanced with the rise of aging temperature, while the coercivity rapidly falls.
It is probable that the origin of the excellent permanent magnet properties of the Fe–Pt alloy is related to the existence of the very imperfect γ₁ phase in regard to constitution and ordering, and these cause the pinning of the magnetic domain wall.

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