Since the present-investigators found new magnet alloy “Malcolloy” of high coercivity in the system of cobalt and aluminium, they have carried out studies of the effect of additions of nickel, molybdenum, titanium, vanadium and chromium on its magnetic properties and obtained the highest coercive force of 1600 Oe. Further, they have investigated the effect of the addition of tungsten on the permanent magnet properties of Co–Al alloys and discovered that the addition of tungsten increases the coercive force of the binary alloys. The alloy which exhibits the highest coercivity has the composition of 75.89% Co, 13.55% Al and 10.56% W and shows the coercive force of 1450 Oe, the residual magnetic flux density of 3100 G and the maximum energy product of 1.40×10⁶ G·Oe when tempered at 525°C for 150 hours after water quenching from 1380°C. These alloys consist of many ferromagnetic elongated particles about 350 Å in diameter which are dispersed in the matrix of nearly nonmagnetic β′ phase. Consequently, it may be concluded that the high coercivity of these alloys is mainly caused by the presence of the fine particles of a single magnetic domain.

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Since the discovery of new magnet alloy “Malcolloy” having a high coercive force in the system of cobalt and aluminium, the present investigators have continued researches on the effect of additions of nickel, molybdenum, titanium, vanadium, chromium and tungsten on the properties of Malcolloy ; the highest coercive force obtained with each alloy is 1450 to 1600 Oe. In this report the effect of manganese addition on the properties of Co–Al alloys was examined, with the results that the coercive force of the alloys decreases and the residual flux density increases gradually with increasing manganese content: The maximum energy product shows the highest value in the alloy containing 84.59% Co, 12.81% Al and 2.60% Mn which exhibits a maximum energy product of 2.50×10⁶ G·Oe, a residual flux density of 5900 G, and a coercive force of 860 Oe, when tempered at 525°C for 20 hours after water-quenching from 1375°C. These alloys consist of many ferromagnetic elongated particles about 350 Å in mean diameter which are dispersed in the matrix of the nearly nonmagnetic β′ phase. Consequently, it is considered that the high coercivity of the alloy is mainly due to the presence of the fine particles of a single magnetic domain.

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An investigation of the effects of quenching and aging temperatures and of additional elements on the aging characteristics of copper-2 wt% beryllium alloys has been carried out mainly by means of electrical resistance measurements. It has been found that appreciable clustering of solute atoms occurs during quenching and the rate of pre-precipitation during isothermal aging increases greatly with increasing quenching or aging temperature. It has also been observed that the increase in resistivity decreases with increasing aging temperature. The activation energy for the zone formation in the high purity binary alloy after quenching from 800°C is estimated to be 1.1 eV. The effect of additional elements on the zone formation process can be summarized as follows; magnesium and zinc accelerate zone formation, whereas cobalt and iron retard it. The results are interpreted in terms of a rather simple picture of the pre-precipitation phenomenon. The role of vacancy appears to be a fundamental one in determining the rate of zone formation. The variations of the maximum increase in resistivity against the various aging temperatures have been explained in terms of the variations of the number of zones formed. Other related problems such as the reversion and effects of additional elements are also discussed.

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The effect of the initial oxygen content on the formation of a layer-like inclusions group was investigated by dropping an aluminum bar onto static liquid iron containing various amounts of oxygen. Chromium and carbon were also added in the liquid iron to control the initial oxygen content and the influences of both elements on the formation of the inclusions group were investigated. The results were;
(1) No formation of the inclusions group was confirmed at the low initial oxygen content in the liquid iron.
(2) This phenomenon was discussed successfully from the viewpoint of the effect of oxygen content on the interfacial energy between liquid iron and solid alumina.
(3) Ferro-carbon alloys yielded the same results as in the case of pure iron, but ferro-chromium alloys with the relatively higher oxygen content resulted in no formation of this group.
(4) These results were explained in terms of the effect of high chromium content on oxygen activity in liquid steel.

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Ageing characteristics in a supersaturated Al–6 wt% MgZn₂ quasi-binary alloy have been investigated principally by a calorimetric method with particular emphasis on the thermal stability of Guinier-Preston zones. Ageing sequence in the alloy is as follows; supersaturated solid solution—G. P. zones—intermediate M′ phase—stable M (MgZn₂) phase. It has been found that G. P. zones can be formed on ageing below 340°C which corresponds to the solvus temperature of the M phase. The intermediate precipitate phase M′ is formed preferentially on ageing below 70°C and the equilibrium M phase precipitates predominantly above 100°C.
Reversion temperature of the zones increases with ageing time for a certain period, after which it has a tendency to saturate to a definite temperature depending on the ageing temperature. The reversion temperature varies from 170°C for the alloy aged at room temperature to 300°C for the alloy aged at 190°C.
It has been found that the activation energy for the reversion of G. P. zones determined from the specific heat versus temperature curve depends upon the ageing temperature.

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Aluminium was embrittled in Hg-3% Zn and Sn-10% Zn. With increasing temperature, the ductility was restored and a ductile-brittle transition was observed. The dependence of transition temperature on the grain size was different in two liquids; in Hg-3% Zn the transition temperature was higher as the grain size became smaller, and in Sn-10% Zn the tendency was reversed.
The results are discussed in terms of stress concentrations for crack nucleation (brittle fracture) and yielding at the tip of the piled-up dislocations. There is a discrepancy between prediction and experiment for the annealed specimen wetted with Hg-3% Zn. To explain this, an expression “stress for definite plastic flow” is newly introduced.
In a subsidary experiment on the pre-strained specimen, the stress introduced is made to be of the same order of magnitude as the yield stress which can be determined experimentally. The above prediction is in excellent agreement with the experimental results.

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The ductile-brittle transition temperature of aluminium in the presence of Hg-3% Zn or Sn-10% Zn liquid was investigated as a function of strain rate. In both liquids, the transition temperature was higher as the strain rate increased. The change of the transition temperature in Hg-3% Zn was 53°C in the strain rate range used in the investigation, but that in Sn-10% Zn was only 10°C. The results were discussed on the basis of stress concentrations for crack nucleation and yielding at the tip of the piled-up dislocations. However, the discrepancy between prediction and experiment was obtained in the case of Hg-3% Zn, and this can be understood in terms of the “stress for definite plastic flow” introduced previously.

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The present study was made of a new method by which the activities can be measured without regard to the substitution reaction in the cell. By this method, it is possible to measure the activities of an extremely dilute solution and also the activities of more noble components in a binary molten alloy which cannot be measured by a usual method. In the measurements, special attention was paid to minimize hum in the synchroscope. It was found that the activities of both components in the binary alloy are measured with good accuracy.

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The internal friction of carbon in α-iron solid solution has been measured for the same specimen in both bending and torsional oscillation modes. The relaxation strength of the measured Snoek peaks for a randomly oriented polycrystalline specimen for the torsional stress was larger than that for the tensile stress by a factor of about 1.18. This is not consistent with the prediction of Snoek that the two values should be the same, but is in good agreement with a calculation made by two of the present authors. That is, the ratio of the torsional and bending relaxation strengths, Δ_G⁄Δ_E, has been found to be about 1.14 in the uniform stress approximation and 1.32 in the uniform strain approximation. The grain size dependence of the relaxation strength has also been similarly investigated. The ratio Δ_G⁄Δ_E was independent of grain size when the specimen had no preferred orientation or texture.

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This study has been carried out to clarify the interactions between metals and molten salts. As one of a series of researches on mixtures of metals with molten salts, the electrical conductivity of salt-rich solutions of silver in molten bismuth trichloride has been measured. For this system, when silver is dissolved into molten bismuth trichloride, the following reaction is considered:
3Ag+BiCl₃=3AgCl+Bi.
Bismuth thus produced, however, dissolves into molten bismuth trichloride as has been well known. The solution, therefore, is considered to be a mixture of silver chloride and bismuth-bismuth trichloride. For the region ranging from pure salt to 30 mol % Ag content, the electrical conductivity was measured by means of the capillary cell method with an alternating current in the temperature range 250°∼400°C under argon atmosphere. The electrical conductivity increased almost linearly with increasing Ag content in every temperature range. It has been shown that below 13.5 mol % Ag and at temperatures lower than 350°C the ionic conductance is predominant, but in a range of above 13.5 mol % Ag and temperatures higher than 350°C the semiconducting mechanism becomes predominant which can be explained by the electron hopping model.

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Since Johnston and Stein showed that the dislocation velocity exponent, m^*, could be obtained from strain-rate change tests, much subsequent work has been made to estimate it for single and polycrystals of iron. In the present study, the effect of strain-rate on the flow stresses of spheroidite and pearlite was examined in order to determine the value of m^*. It was found that, if the thermal components of yield stress were used in the calculation, m^* was in fairly good agreement with those of α-iron single crystals, being independent of particle or lamellar spacing. The activation volumes were in-accord with those of α-iron, too. From these results, it is concluded that the thermal components of yield stresses in these structures are essentially due to the resistance to the motion of dislocations in the matrix.

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The viscosity of Fe–C–Si alloy (3.5%C, 1.20%Si) was measured by the oscillating crucible method to investigate the presence of hysteresis and the difference in viscosity between white and grey iron melts of the same chemical composition, and to clarify a problem on the heredity of cast iron whose properties after melting depend upon charge materials. The results obtained are summarized as follows: (1) Viscosity curves measured in the superheating process did not correspond with those in the cooling process over the temperature range of 1255° to 1480°C: a negative hysteresis was recognized as proposed by Turovskii. The higher the maximum heating temperature, the wider became the hysteresis. (2) In this temperature range the viscosity of grey cast iron was higher than that of white cast iron. (3) In case of holding the melt at 1342° and 1288°C, the change in viscosity coefficient with time decreased rapidly by 20 minutes of holding. Subsequently, the difference between the white iron and grey cast iron melts was clearly recognized, where the viscosity of the latter was higher than that of the former. (4) With increasing Si content up to 0.43%, the hysteresis was hardly recognized, but over 1.22% Si there appeared the negative hysteresis. In both superheating and cooling proceses the viscosity showed a maximum at 1.22 %Si and a minimum at 0.43 and 2.70 %Si, respectively.

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