A theoretical calculation of the free energy of solution of binary silicates is presented. Based on a random network model, a quasi-lattice treatment was applied to evaluate the partition function which has a parameter characteristic of the basic oxides. Calculated activities of the components and the free energy of solution as functions of composition fairly well reproduce experimental results. A basicity scale of oxides was defined in terms of the parameter.

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Kinetics of the vacuum thermal decomposition of Mo₂S₃ pellet into metallic Mo was studied. This reaction plays an important role in the direct winning process of metallic Mo by thermal decomposition of MoS₂. Isothermal weight loss measurement was carried out with 0.5 g, 0.4 g and 0.3 g disc-shaped pellets at 1140°∼1440°C. The pressure within the reaction tube was kept at about 5×10⁻⁵ mmHg.
Concerning the rate-determining step of the reaction, a heat transfer model and a mass transfer model were examined.
The heat transfer model assumes that the heat transfer rate from surroundings to the decomposing interface determines the overall rate. This model was not accepted because a linear rate equation from this model could not explain the parabolic relationship between the decomposition fraction and the time. The mass transfer model assumes that the outward diffusion of sulphur gas through porous Mo shell controls the overall rate. Based on this model, the parabolic kinetic expression was obtained which can explain the experimental results. The change of the rate constant with the pellet thickness can also be explained. The effective diffusivity of sulphur gas was estimated at 1 to 3 cm²/sec.

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Investigations were made on the dislocation distribution near the crystal surface parallel to the cross slip plane of weakly deformed copper single crystals whose axial orientations lie on the great circle, ⟨110⟩–⟨112⟩, using an etch pit technique. The dislocation density was highest at the crystal surface. It rapidly decreased near the crystal surface (surface hardened layer) and then gradually in the interior with the distance from the crystal surface. The surface hardened layers in two crystals which were led just to the yielding point and elongated up to the intermediate stage of the easy glide region were 40 and 70μ in thickness, respectively.
Two kinds of dislocation distribution were observed near the surface; (1) long and straight dislocation arrangements in a row along the primary slip trace and (2) rather randomly distributed dislocations between the rows of (1). With increasing depth toward the interior, however, the former changed to dislocation bands and the latter disappeared.
It was concluded that the high dislocation density near the crystal surface of weakly deformed copper came from the preferential activation of the surface sources not only of the primary but of the latent slip system.

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The present work was aimed at obtaining knowledge about the formation of inclusions after solidification. A hole was bored in the solid iron containing oxygen and filled with a pure aluminum wire; and they were held at 1450°C for half an hour to three hours, in order to investigate the distribution of the formed inclusions. The results were obtained with the naked eye and by the microscope and the microanalyzer. The results are;
(1) The stratiform inclusions group was formed near the boundary between liquid aluminum and solid iron, namely at the solid-liquid interface.
(2) The inclusions were much smaller than those formed during the deoxidation of liquid iron with aluminum.
(3) The stratiform inclusions group consisted singly or in various combinations, of alumna, spinel hercynite and wüstite.
(4) The distribution of the inclusions forming the stratiform group could be successfully explained by assuming that the behavior was the same for the solubility of oxygen in solids as in liquids.

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Sufficiently pure aluminum was put onto solid iron containing various amounts of oxygen (1) in order to investigate the effect of oxygen on the formation of the inclusions as well as the formation behavior of the inclusions with a large supply of aluminum, and (2) in order to measure the displacement of the solid-liquid interface which is important in the discussion on such a reaction. The following results were obtained from observations with the naked eye and by means of microscopy and microanalysis by controlling the initial oxygen content and the reaction time:
(1) There were three distinguishable regions in the specimens; region (I) with more than about 50% aluminum region (II) with 20%∼50% aluminum and region (III) nearly free from aluminum.
(2) The thickness of region (II) increased with increase in reaction time, but decreased with increasing initial oxygen content.
(3) The stratiform inclusions group was formed near the boundary between regions (II) and (III), namely at the solid-liquid interface.
(4) With increases of the initial oxygen content in solid iron and the reaction time, the inclusions grew excellently and increased in density.
(5) The removal of the solid-liquid interface increased with increase in reaction time, but decreased with increasing initial oxygen content.
(6) An empirical linear law held good for the displacement of the interface between regions (I) and (II), independent of the effect of the initial oxygen content. A parabolic law held for to the displacement of the solid-liquid interface, in which case there was the effect of the oxygen content.
(7) The diffusion of aluminum into iron was successfully analyzed by using the diffusion equations with a precipitation as discussed by Hermans and others.
(8) The aluminum content in the matrix which was corrected by using Philibert’s equation agreed well with that estimated from the relative intensity of iron. But Barks’ correction has deviations from the actual data.

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A decrease in electrical resistivity of niobium-hydrogen alloys is observed during the isothermal aging at −196°C. It is shown that the aging process is a reaction with the time exponent of 1/3 and the activation energy of 0.10±0.02 eV . A change in flow stress is also observed with the aging at this temperature. These phenomena are not found in hydrogen-free niboium. It is suggested that the changes in resistivity and flow stress should be attributed to the hydride precipitation at −196°C.

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Quantitative analysis of autoradiograph requires the knowledge of intensity profile produced by the specific distribution of a radio isotope is necessary. But the knowledge about the planar distribution of radio isotopes has so far been lacking. In this paper calculation is carried out on the intensity profile caused by planar distribution of radio isotopes of ⁷⁶As and ¹²¹Sn (both are beta-ray emitters) which is expected to exist in case of grain boundary segregation. In carrying out the calculation, absorption of radiation by the specimen is taken into account. In case of ⁷⁶As having the maximum energy of beta-ray, E_max=2.965 MeV, the half width (h) of the intensity profile is 32 microns for the specimen thickness b=10 microns, and is 80 microns for b=320 microns, while in case of ¹²¹Sn having E_max=0.383 MeV, h is 24 microns for b=10 microns and 27 microns for b≥30 microns. The background intensity is also calculated for each isotope and it is found that the higher the particle energy and the thicker the specimen, the stronger the background intensity becomes. The S/N ratio (the ratio of the signal due to the segregated solute to the noise due to the background intensity) becomes larger as the energy of beta ray and the thickness of the specimen decreased.

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Autoradiograph was taken in order to detect the grain boundary segregation of As and Sn dilutely alloyed in pure iron after two kinds of heat treatment. As and Sn activated in a reactor were melted with pure iron. ⁷⁶As and ¹²¹Sn which have a similar half life of about 27 hr were used as the tracer. The alloys contained 0.074 and 0.21 wt% As, and 0.14 and 0.64 wt% Sn, respectively. Melted specimens weighing 20 g were homogenized and then forged. The final heat treatments are as follows: For As alloys, 950°C×1 hr, water quenched or furnace cooled, while for Sn alloys, 1000°C×1 hr, water quenched or furnace cooled, respectively. Ground and polished specimens which have a final thickness of 0.4 to 0.8 mm and a grain size of 110 to 360 microns were subjected to autoradiography, but after all any positive contrast suggesting the existence of grain boundary segregation was not detected.
The absence of any positive contrast of grain boundary segregation observed by the present experiment was examined on the basis of two models of grain boundary segregation, referring to the results of calculation of the intensity profile presented in the previous paper.
(1) If there takes place grain boundary segregation in conformity with the McLean model which assumes the formation of a three atomic segregation layer the segregation cannot be detected by the present experimental method.
(2) If a grain boundary segregation with a 10-micron layer suggested by Westbrook takes place, the solute content within the segregated layer will be less than 1.27 and 1.09 times that of the interior of the grain for As and Sn alloys, respectively.

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Single crystals of iron base molybdenum alloys containing a high volume fraction of precipitated particles Fe₂Mo noncoherent with the matrix were extended at various temperatures between −110° and 200°C. Critical resolved shear stresses in these single crystals depended on the particle size, mean interparticle spacing, and deformation temperature, but not on the crystal orientation of the single crystals used. The increment of the macroscopic yield stresses by the precipitated particles was obtained by subtracting the solid solution strengthening of the matrix from the observed yield stresses in the aged specimens. It was found that the stress increment by the noncoherently precipitated particles was explained fairly well by the Orowan’s mechanism in this alloy system. At the initial stage of plastic deformation, neither primary nor cross slip lines could be resolved by replica-electron microscopy. On the other hand, at a large strain of about 8%, cross slips were clearly observed to take place over a distance of the order of particle size. The changes in crystal orientation with extension were barely perceptible in the over-aged Fe-10%Mo alloys, probably less than 1 degree even after 10% elongation. The increases in flow stress due to work hardening seemed to be rather independent of the crystal orientation of aged specimens and deformation temperature. This can better be described in terms of a secondary slip theory by Ashby than a model proposed by Fisher et al..

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An electron microscope observation was conducted on the cell structure of cast Al–Mn alloys in the composition range between 0.1 and 6wt%Mn. Solidification and cooling rates were high enough to keep nearly all Mn in supersaturated solid solution for all alloys. At concentrations of 0.5% Mn and higher, dislocation arrays were observed along the cell boundaries, while at nodal points small second phase particles could be detected. In general the nature of cell boundaries did not change decisively over the whole composition range investigated, although some changes in the degree of dislocation alignment and the frequency of second phase particles were noticed. Dislocation densities were low in all alloys. This finding is correlated to low micro-segregation at the cell boundaries as observed by microprobe analysis.

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In order to clarify the fine structure and the origin of the lineage boundaries, aluminium single crystals were grown from the melt under various conditions and investigated by transmission electron microscopy, the selected area electron diffraction method, and the X-ray Laue and pseud-Kossel diffraction methods. Three types of the sub-boundaries were found in accordance with the changes of the purities and the growth rate; they were of type (1) which was composed of a regular array of dislocations, type (2) of the dislocation networks and type (3) of the wall of fine tangling dislocation segments, respectively. While the sub-boundaries of types (1) and (2) do not lie on any peculiar crystallographic plane, the type (3) sub-boundaries lie mostly on {311} or {211} planes. From a sudden disappearance of all the dislocation contrasts at a certain tilting angle even in the case of type (3), it was concluded that strains around the fine tangling dislocations may be described by a certain vector B which is a sort of resultant of the Burgers vectors of the dislocations in problem and satisfies the condition g·B=O, where g is the reciprocal lattice vector of the reflecting plane. On the basis of the above observations, the origin of the lineage boundaries was discussed, and it was suggested that the interactions between edge dislocations, screw dislocations and impurities may play an important role in their formation.

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Hardness measurements and microscopic observations by both optical and transmission electron microscopy were carried out mainly on a beryllium-3wt% iron alloy.
The alloy was solution-treated at 1150°C, followed by oil-quenching, and aged at 400° to 700°C for a various time. In the quenched specimens, helices and loops of dislocations were observed. The ageing treatment resulted in climbing of the dislocations and also preferential precipitation on dislocations as well as at grain-, twin-, and sub-boundaries.
Although the change in hardness due to ageing was not so large, two different stages were found in the ageing process, and it was considered that the first stage was associated with the climbing of dislocations and preferential precipitation onto dislocations, and the second stage with effective homogeneous precipitation.
The composition of precipitates was identified to be Be₁₁Fe, and the crystal structure of the precipitates and their orientation relationship with the matrix were the same as those reported by Rooksby.

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