In order to investigate mainly a primary step of the silicothermic reaction, the behavior of the electrical resistance for the briquettes of ferro-silicon alloys and calcined dolomite was measured. The results obtained explain the following phenomena: (1) The primary reaction between silicon and calcium oxide is very fast to produce the calcium silicide phase in the briquette. (2) The addition of suitable amounts of calcium fluoride may affect the primary reaction and accelerate the overall reaction. (3) The ferro-silicon alloys with about 75 and 80% silicon are suitable for the silicothermic reaction. (4) Increasing the briquetting pressure sometimes stifled the progress of the reaction.

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The mechanism and kinetic behaviors of ordering in Fe₃Al alloy have been investigated by means of an X-ray diffraction. The size of the ordered domains is small near the two critical temperatures for transformations disorder\ ightleftarrowsB2 and B2\ ightleftarrowsDO₃, while it is much larger below these temperatures. The variation in the degree of order of the DO₃ type with quenching temperature is in good agreement with the theoretical results obtained from the Bragg-Williams approximation below the critical temperature for the transformation B2\ ightleftarrowsDO₃. The isothermal ordering in quenched Fe₃Al is caused by the nucleation and growth of DO₃ domains in the B2 matrix. The activation energy for isothermal ordering is 37 kcal/mol. The observed broadening of the 440 fundamental line on annealing supports that the ordering is due to the heterogeneous process.

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Studies on grain growth phenomena leading to the formation of the texture with a strong (110) [001] component were carried out dealing with strain-anneal and secondary recrystallization of Fe-3.25% Si alloy. The configuration of crystallines after primary recrystallization was investigated in reference to impurities. Thereby, in the process of accumulation of impurities along grain boundaries after the primary recrystallization, the transport effect by the migrating boundary is involved. The contribution of the coincidence boundary was also discussed.

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Grain boundary migration of poly- and bi-crystalline silver under compression at 500°C was observed by means of a high temperature microscope. The results for the polycrystalline specimen are as follows; Thermal etching of grain boundaries took an impractically long time under the stress-free condition, while the boundaries could be detected within about one second under applied stress. One grain was absorbed by the surrounding grains. Twin boundaries intersecting a grain boundary restrained the grain boundary migration.
When a bicrystalline specimen with a curved grain boundary was subjected to strain gradient compression, the grain boundary migrated at first toward the low strain side (center of curvature) and then toward the high strain side. The driving force of the grain boundary migration was thought to arise from the grain boundary energy in the early stage and from the stored energy of deformation in the later stage. The increase in the mobility of a grain boundary under applied stress was interpreted as due to strain enhanced self-diffusion in the grain boundary.

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The relation between the nickel content and the hardening capability of Ni-rich NiTi compounds, and the effect of heat treatment on the mechanical properties of a NiTi compound containing 54.7 at%Ni have been investigated. NiTi compounds containing more than 52 at%Ni show a considerable increase in hardness by quenching, and the maximum hardness is obtained at about 54.5 at%Ni. According to the phase diagrams which are considered to be most reliable, the composition from which the hardening effect appears corresponds to the composition of the boundary between the NiTi phase and the NiTi+Ni₃Ti phase at lower temperatures and the composition at which the maximum hardness is obtained coincides with the composition of the same boundary at the quenching temperature. This fact seems to suggest that the hardening capability in Ni-rich NiTi compounds is related to the existence of excess point defects which are introduced by the deviation from the stoichiometric composition at the quenching temperature. The NiTi compound containing 54.7 at% Ni is hardened by quenching from temperatures above 600°C, and the hardness increases with increasing temperature. When the NiTi is quenched into water from 1100°C, the Vickers hardness of about 700 is obtained. The hardness of the quench-hardened NiTi decreases with annealing time. However, no hardening effect due to the precipitation of Ni₃Ti is observed. The tensile strength of the NiTi is 80 kg/mm² in the annealed state and 100 kg/mm² when annealed at a relatively high temperature after quenching. Although the Young’s modulus of the NiTi in the annealed state is anomalously low as compared with the values of the constituent metals, quenching from 1000°C gives a nearly 20% increase of the value.

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A fundamental study of iron soldering has been made of the reaction of solid iron with molten tin from the viewpoints of dissolution kinetics and metallography. Small iron cylinders were immersed in molten tin in the temperature range from 445 to 780°C for 10 to 160 min under a static condition utilizing the soldering flux. The obtained values of initial dissolution-rate constant of solid Fe into molten Sn are 3.37×10⁻⁴∼1.12×10⁻³ cm/sec and the activation energy for dissolution depends on the temperature. Owing to the formation of intermetallic compound in solid-liquid interface, the dissolution behaviour in the high-temperature range above 496°C differs from that in the low-temperature range below 496°C. The intermetallic compound formation does not appear to act as a dissolution barrier. In the high-temperature range, the dissolution process is controlled by diffusion in the boundary layer of molten metal. In the low-temperature range, the process is controlled by the formation of an intermetallic compound at the early reaction time, but a transition of reaction control of the alloy layer and molten metal occurs with time. The dissolution of solid iron into molten tin proceeds with an intensive reaction between molten tin and the alloy layer in relatively rapid growth.

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The feasibility and the mechanism of activation of pyrolusite, manganite, and rhodochrosite with Fe (III), Cu (II) and Mn (II) in an anionic collector system using oleic acid as the collector have been investigated. The results obtained showed a certain regularity as basically determined by the acidity of the heavy metal cation and the pH of its precipitation, the pK_a of the oleic acid, the chemical composition of the manganese mineral tested, and the pH of its isoelectric point. Thus, Cu (II) and Mn (II) which are basic and hydrolyze at pHs above those of the isoelectric points of the manganese minerals investigated could, within certain specific limits of medium pH, act as activators for pyrolusite and manganite. On the other hand, Fe (H₂O)₆⁺⁺⁺ which is acidic, ionizes at pH 2.2 and is precipitated at pH 3.7, which is below than both the isoelectric point of the manganese minerals studied and the pK_a of oleic acid, is of no particular advantage in the activation and flotation. The response of rhodochrosite, without pre-activation, to soap flotation seems to be due to the basic property of the bivalent manganese sites in its crystalline lattice, which produces a tendency for the attachment of oleic acid. Owing to the negative surface charge of the manganese minerals at pH above 5 and the positive surface charge of the gangue minerals (barite, gypsum, calcite), the anion, Al₂SiO₃(OH)₆⁻⁻, resulting from the conjunction of Na₂SiO₃ with Al₂(SO₄)₃ is adsorbed preferentially to the surface of the latter leading to a successful differential flotation.

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The aqueous oxidation of zinc sulfide in deaerated dilute hydrochloric acid solutions containing sodium chloride at pH 1∼3 was studied by means of an electrochmical method. The test electrode was a mixture of electric conductive paint and metallic sulfide. Both anodic and cathodic polarization behaviors were measured by means of a potentiodynamic polarization method. The experimental results obtained were as follows:
(1) The S⁰ producing type reaction of zinc sulfide dissolution was accelerated by raising the temperature, at low pH values in an appropriate potential range. The overall reaction was as follows: ZnS+1/2 O₂(aq.)+2H⁺→Zn²⁺+S⁰+H₂O. The half-cell reactions were: ZnS→Zn²⁺+S⁰+2 e⁻ (anodic oxidation) and 1/2 O₂+2 H⁺+2 e⁻→H₂O (cathodic reduction).
(2) The S⁰ producting type reaction of zinc sulfide dissolution was also accelerated by the activation treatment of zinc sulfide, and the reaction rate increased with increasing concentration of cupric sulfide in place of the zinc sulfide surface layers. The S⁰ produced by the anodic oxidation of zinc sulfide was amorphous.
(3) The acceleration of the S⁰ producing type reaction in the dissolution of activating zinc sulfide was caused by the formation of a galvanic couple of the ZnS–CuS system. Zinc sulfide was anodic and cupric sulfide acted as the cathode to the reduction of aqueous oxygen in the solution.

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Measurements of Young’s modulus at −150∼400°C and of rigidity modulus and hardness at room temperature have been carried out for Mn–Cu–Co alloys subjected to a variety of heat treatment and cold working conditions. It is shown that the ternary alloys slow-cooled after heating at 900°C for 1 hr reveal anomalous changes associated with antiferromagnetic\ ightleftarrowsparamagnetic transformation on the Young’s modulus at room temperature curves. The Young’s modulus at room temperature does not show any appreciable difference by the state of annealing, cold working or water quenching while the Mn and Co concentrations are relatively small. The difference becomes conspicuous as the Mn or Co concentration is increased. The temperature coefficient of Young’s modulus undergoes a marked variation by annealing, cold working, water quenching, and reheating after cold working or water quenching as well as with alloy composition. It is also to be noted that the temperature coefficient of Young’s modulus vs composition curves show large maxima in positive and negative signs, thus indicating the Elinvar characteristics. The rigidity modulus and its temperature coefficient at room temperature represent a very analogous variation to that of Young’s modulus and its temperature coefficient with composition, heat treatment and cold working. The values of hardness are higher in the state of reheating after cold working or water quenching than those in the state of annealing, cold working or water quenching, and the corrosion resistance is fairly satisfactory.

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The authors have previously found that a thin plate-like martensite which is entirely different from lenticular one is formed at temperatures below about −150°C in Fe-Ni-0.25%C alloys. In this paper, the morphology of thin plate-like martensites (both thermally transformed and strain-induced martensites) which were formed at liquid nitrogen temperature in Fe-31%Ni-0.23%C (Ms = −190°C, Fe-31%Ni-0.28%C (Ms = −171°C and Fe-33.5%Ni-0.22%C (Ms < −269°C was precisely observed. These martensites are usually very thin and have a smooth straight boundary with austenite. Transformation twins run completely through the martensite plate and no mid-rib is observed. The habit plane of this martensite is near {259}_γ. This plate-like martensite shows a peculiar nature in morphology which can hardly be observed in the usual lenticular martensite. The thin plate-like martensite can cross each other and make kinking or branching. The martensite plate is considered to be thickened by a combination of many parallel thin plate-like martensites with same variant. Consequently, the thick martensite contains many parallel faint boundaries which are boundaries of the original thin plate-like martensite. Furthermore, it seems that this martensite has the nature capable of gradually growing sidewise.

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The present study was carried out so as to ascertain whether or not the TIE method can be applied with good accuracy at higher temperatures. The activities of component PbO in the PbO–SiO₂ melt were measured at 950 and 1050°C.
In the moment the standard melt (N_PbO=0.928) makes contact with both electrodes, the concentration cell is constituted as follows:
Pb|PbO–SiO₂ (standard)|PbO–SiO₂ (measuring)|Pb.
It was found that the experimental results were satisfactory compared with the datain the literature and the values calculated thermodynamically for the compounds PbSiO₃ and Pb₂SiO₄.

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The discrepancy between the activities measured by the e. m. f. and the vapor pressure method was investigated based on the rule of phase constitution and the concept of the surface and body activities. There is a regularity of changes in a series for the discrepancy between the two kinds of activities as is observed for the rule of the phase constitution.
The difference between both activities seems to be related to the electric charges existing in molten alloys. These facts led to the conclusion that the surface activities measured by the e. m. f. method differ substantially from the body-like activities by the vapor pressure method.

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The ageing characteristics of Cu-0.9, 1.4 and 2.3 % Fe alloys were studied by transmission electron microscopy, and measurements of various mechanical properties, the electrical resistivity and the saturation magnetization. Changes in 0.1% proof stress, tensile strength and hardness during ageing were confirmed to show simple single peak curves against ageing time. The main precipitate is initially a spherical coherent particle, and the precipitate grown larger than about 700Å, generates some interfacial dislocations and becomes quai-coherent. Further, grown non-coherent particles with a higher density of dislocations punch out many dislocations into the matrix and preserve a fcc structure. Coalescence of the spherically coherent particles follows the coasening equation of the form \barR³−\barR₀³=α(t−t₀) fairly well. The precipitate particles are paramagnetic during the ageing and almost all the particles larger than about 100Å in diameter were transformed to ferromagnetic by 93% cold rolling. The transformation of the particles proceeds with increase in tensile strain, and for the larger particle size, the volume fraction transformed by a small strain becomes larger. A very small amount of discontinuous precipitates with a fcc structure is observed at some of grain boundaries in the aged specimens.

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