The thermodynamical functions (free energy, chemical potential and activity, etc) of the interstitial solid solutions were derived by the statistical thermodynamical methods. By comparing these functions with the experiment,mainly with the R.P.Smith’s activity data of carbon in γ- and α-iron,energy constants and the special characters of Fe-C interstitial solid solution were investigated.As the α-γ metastable equilibrium under A₁ transformation point is important in the theory of heat treatment of carbon steel,these metastable equilibrium lines were calculated by using above functions and the physical constants.The result is as follows ; G P A line(solubility line of carbon in α-iron,) increases with temperature lowering,and has a tendency of conciding with Ar″ line.(Fig. 6).

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Following the first report, we have observed light figures produced by the three principal crystallographic planes {0001}, {11\={2}0 and {10\={1}0 of zinc single crystals, etched for different time-intervals with hydrofluoric acids or aqueous solutions of various salts, and examined the suitability of those figures for the determination of crystal orientations by the method of light figures, The results obtained are summarized in Table 1 of the text.
Distinct light figures of hexagonal symmetry are observed on {0001} planes by a short-time etching with concentrated (40 percent) hydrofluoric acid,with a saturated aqueous solution of cupric chloride,with mixtures of saturated aqueous solutions of sodium sulphate and of chromic acid anhydride (95:5∼80:20),or with dilute aqueous solutions of ammonium persulphate; these figurs are suitable for determining an angle between the axis of a specimen crystal and the hexagonal axis ⟨0001⟩. While,light figures of digonal symmetry on {11\={2}0} or {10\={1}0} planes obtained by etching with any one of the above-mentioned reagents are not so suitable or unsuitable for determining angles between the axis of a crystal and the digonal axes of the first kind ⟨11\={2}0⟩,owing to the indistinctness or the inadequate form of the figures or the long etching-time required. Reagents other than those mentioned above produce indistinct light figures or nothing.

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On the lattice transformation occurring in case of supercooling of γ phases of the Fe-C and Fe-Ni alloys the following notable phenomena were observed; Lattice transformation can scarcely proceed at a temperature at which it begins even if the alloy is preserved for long hours at that temperature. There exists a characteristic interval of temperature which has little connection with cooling rate except for the extreme cases of higher or lower cooling rate. Temperature intervals rather increase when the cooling rate is extremely small after the transformation begins. If cooling is then continued again,it does not occur at once but after leaving a considerable shift of temperature it follows to progress again. In this case the larger the amount which had transformed before interruption of cooling,or the longer the duration of interruption, the larger the shift of temperature is.
The phenomena concerning the items(1) and (2) mentioned above were discussed in the 1st report in which the phenomena of temprature interval were reduced to that of the strain-hardening in the plasticity by assuming a relation that the free energy difference dissipated in the lattice transformation γ→α was equal to the mechanical energy required for plastic gliding-like deformation on the occasion of transformation. On the same stand point we can reduce the phenomena of the items(3) and (4) to the effect of loading rate on the stress-strain relation and the age hardening in worked metals respectively.
The observed thermal dilatation curves showing the temperature interval under various cooling rate (Fig. 1) can be rewritten in the form of stress-strain curves under various loading rates (Fig. 2) through the above relation. These figures show that the above consideration seems to be reasonable.

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In the various oxygen pressures, we investigated the temperature dependency of the electrical conductivity (σ) of NiO. It changes from the form Aexp(−E⁄kT) to A′exp(−E⁄2kT) with the increase of oxygen pressure (P:10⁻³∼760 mmHg). From this change we can determine the unique value of the activation evergy E. E=1.25 eV. The dependency upon the oxygen pressure at a definite temperature can be expressed generally,by the formula, σ∞P^\frac1x. If we assume, as usual, that when the oxygen pressure increases,the nickel ions moves towards the surface to react with oxygen and extend the lattice of NiO, leaving vacant lattice points on the nickel lattice of NiO, and that such vacant lattice points form the impurity levels, then we can obtain the relation σ∞P^\frac14. Experimental value of x is 3.7 at 1000°,almost in accord with the above-mentioed result. But at lower temperatures we gain the smaller value of x,until finally it reaches to the relation σ∞P. And with such assumption,we cannot explain the change of the temperature dependence of the conductivity in the different oxygen pressures.
So,we assume that the nickel ions which left the normal lattice points,partially extend the lattice NiO at the surface,and partially occupies the interstitial positions. Then, thenumber of the vacant lattice points (N_h) is proportional to \sqrtP,and the number of the interstitial nickel ions (N_f) is inversely proportional to\sqrtP.
So the number of electrons at the imprurity levels,and of positive holes in the full band varies depending upon the oxygen pressure. Using these relations,we can derive the theory which may account for the experimental data.
From our data,we get a constant δ=N_f⁄h\simeq2×10⁻³ at 1000°, P=760 mmHg, in which n denotes the number of free positive holes. This value of δ is very small, nevertheless the effect of this small value is very serious.

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The magnetic properties of ternary alloys of iron,silicon,and cobalt have been measured,and the relation of these properties to their respective concentration have also been investigated. Those alloys containing about 9∼13%Si, about 13∼20%Co show the permeability maximum region and their representative alloy contains about 10%Si,about 15%Co. Some of its magnetic properties are as follows ; the initial permeability, 470,the maximum permeability,21700,the magnetic hysteresis-loss,330 erg/cm³/cycle,the coercive force,0.22 Oersteds and the residual induction,4650 Gausses at maximum induction,5000 Gausses.

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The magnetostriction of ternary alloys of iron,silicon and cobalt have been measured in various longtudinal magnetic fields of less than 1100 Oersteds. The positive magnetostriction of Iron-Cobalt system gradually decreases with the addition of Silicon, and we obtain the saturation magnetostriction λ_s=0 line. This line crosses to the superlattice line,connecting with Fe₃Si and FeCo, through the maximum range of permeability.

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For this purpose,the authors made use of the direct method,namely the oxidation method by means of the isothermal bombcalorimeter. By this method,one can obtain the heat of formation of the oxide of Al-Mg alloys,viz Al oxides (Al₂O₃):381.0 kcal/mol.Mg oxide(MgO):13.89 kcal/mol and the same values for Al-Mg Alloys(Al 5∼95%) are shown in Fig. 3. Then,the heat of combustion of the mixture of Al & Mg, was measured. From these data,the heat of formation of the compounds of Al-Mg binary system calculated and the results were obtained as follows : 120 cal/formation of Al₈Mg₅; −45 cal/formation AlMg,and −100 cal/formation of Al₃Mg₄.

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It is well known that if deformation proceeds beyond the elastic limit,slip or twin occurs.This investigation is to study the slip which occurs by plastic deformation,and how to change its shape by heat-treatment. Al-Cu alloy was used for the purpose of studying slip by the microscope. Observations were made by tempering for 1 hour at 230C after supersatulation by which CuAl₂ is precipitated preferentially on the slip or grain boundary. As the results of this investigation,slip lamellae change their shape to the veining structure (sub-boundary structure), and they grew with increasing temperature and time,and after this variations,recrystallization follows in the small deformation range.

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The hardness-time curves at various annealing tempratures were explorated for cold-worked α-Brass containing 35.2%Zn,and its changes of electrical resistance were measured in the course of heating with a constant rate. The abnormal hardening processes could be treated as aging phenomena of strain-hardened type because of two facts obtained. First,between the logarithmus of time attained maximum hardness and the reciprocal of the absolute annealing temperature there existed some linear relations, from which the activation energies could be calculated for each working-degree and temperature range. The calculated values were almost conceivable. Second,in the alloy particularly annealed at about 225°C for one hour there evolved some abnormal strains which were confirmed from the resistance changes. In the lower range of working-degree, the “initial softening” followed by proper hardening process was observed also with a regular relation between time and temperature. The very slight hardening perceived sometimes in general just before the recrystalization may be evidently distinguished from the abnormal hardening in case of α-Brass.The above results were compared with those of α-Brass containing 26.5%Zn and a good agreement was gained.

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The intermediate low-temperature annealing was adopted for Copper and Brass at the break point of each work-hardening curves and before or after that point. For the copper the low-temperature annealing brought about slight improving effect upon the subsequent work-hardening. However, for the Brass containing 35.2%Zn, there are two methods of improving effect for use, namely one that the slight softening due to the annealing increases the work-hardening power more strongly than one without such annealing and the other that the so-called “abnomal-hardening” due to annealing maintains the higher value of strength during a few subsequent stages of working. The former principle may be perhaps adopted for the case of Cu-Cd alloy containing 1%Cd, already reported,with almost the same significance, but this alloy displays more powerful effect than the brass because of the more strengthening ability of Cd-atom in the matrix of copper solid solution than the Zn-atom.

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This siliconizing experiment is carried out by packing the low carbon steel or high carbon chromium steel in a mixture of silicon carbide and ammonium chloride at the temperature of 800∼1100°.
In this siliconizing experiment, the rate of diffusion depends on the temperature, the time and the amount of the ammonium chloride.
The exact mechanism of this reaction is not clear.But it is believed that the decomposition of ammonium chloride liberates the silicon chlorides from the silicon carbide in the gassy form, and the silicon chloride into the steel to be treated.

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On the viscosity of molten metals and slags, several investigations bas been carried out, but we have little knowledge about that of molten salts. There are many difficulties in experiment at high temperatures of molten salts, which act corrosively to refractories. Viscositie of molten salts of nitrates and chlorides were measured successfully by a deviced method, in which velocity of a dropping ball made of nickel are measured by means of a chemical balance.

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The effect of 0.1%A′, 0.15%Ti and 0.3%Ti as the deoxidizer as well as the denitrizer on the Temper-brittleness of steels has been studied by the impact-test. By adding these elements the Temper-brittless of steels almost disappeared.
The Temper-brittleness of low Mn steels containing 0.020% Nitrogen disappeared completely by the addition of 0.2%Al or 0.3%Ti, and for the procedure the Temper-brittleness of the Ni-Cr steels containing 0.025% Nitrogen, 0.3%Ti or 0.2 or more % of Aluminium was necesary Phosphor in steels promote the effect of Nitrogen on the Temper-brittleness.
The effects of Aluminium, Titanium,on the Temper-brittleness of steels means that the Temper-brittleness of steels is attributable to the effect of Nitrogen in steel.

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Five case-hardening steel bars with banded structure were normalized or annealed, from which two kinds of specimens were taken in perpendicular (transverse) and parallel (longitudinal) direction to that of rolling and the directional effect on quenching-deformation of these specimens was studied by means of Carl Zeiss universal-measuring-microscope,and Leitz dilatometer as well as by other metallographic methods. The results obtaind are:—When the annealed specimens were heated at about 900° and quenched in water, the difference of length are markedly observed in two specimens, transverse and longitudinal, while in normalized specimens in which no banded structure is seen,the difference is hardly observable by the same treatment. Such a directional difference in length-change in these test specimens is to some extent reduced in magnitude by slow heating or by preheating prior to quenching. From the result of measurement,it was shown that the directional difference in these specimens depends principally upon the behavior of the change of length in transformation at heating of steels.

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The deformation in a self-hardening tool steel containing about 2% of C and 13% of Cr due to heat treatments has been investigated by means of Carl Zeiss universal-measuring-microscope, Leitz dilatometer and Rockwell C-hardness tester. As a result, conditions of heat treatments which give a sufficient hardness for tools with a diminutive amount of deformation were determined, e.g., if the specimens are air-cooled from temperatures between 1050° and 1075° and tempered at 300° to 400°, or air-cooled from 1100° and tempered up to 200°, about 60 in Rockwell C scale with the change in length less than 0.02% is obtained.It was also testified that the change in length in aging at room temperature for the air-cooled or oil-quenched specimens is,if any,extremely small. Furthermore,by the dilatometric measurement,the relation btween the deformation caused on tempering hardened specimens and the transformation of retained austenite,which results in an increase in volume,during cooling from the tempering temperatures, was made clear.

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The deformation due to heat treatments for five kinds of self-hardening tool steel, such as, Cr steel, Cr-Mn steel, two Cr-W steels and Cr-V steel, were investigated. In high C high Cr steel with an addition of about 3% of Mn,owing to the increase in its selfhardening property, a remarkable decrease in length takes place by the air-hardening from 1000° upwards, where as the hardening-deformation is very small on air-cooling from a comparatively low temperature, e.g. 950°. The addition of about 0.8% of W, gives a slight influence upon the hardening-deformation in high C high Cr steel,although a resistance against softening due to tempering increases. In steels containing about 2%C, 12%Cr, 1%V and about 1%C, 3%Cr, 9%W, the hardening-deformation is slight, when the specimens are air-cooled from comparatively high temperatures, e.g. 1050° for the former and 1130° for the latter respectively. In all steels studied, the retained austenite transforms into martensite during cooling from the tempering temperature, resulting in the increase in volume.

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After this war the use of zinc was extremely necessary in our die casting industry,for Al was exhaused. Generally speaking, the zamak alloy was used as zinc die casting alloy,but zinc, defined as Pb<0.003 in the zamak alloy,could not be produced economically and abundantly in Japan.
The increase of Pb content brought about the blittleness on account of the ageing phenomenon, so magnesium was efficient as a protection against the ageing. In the 1948 spring meeting of the Imono Kyokai the authors reported on the relation between Mg and Pb of zamak alloys, made by Japanese zinc.
In this report the authors researched on the effect of Ni and Mn on the zinc alloys.

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In order to investigate sawdusts as a carburizing agent, the generated charring gases have been studied. It has been known that at the early stage of the charring time, when considerably higher temperature is used,there generates a fair amount of gages as CO, CO₂, H₂, C_mH_n±x etc. in the exhaust gas besides condensed water,and tar but as charring duration is prolonged, the exhaust gas becomes inert promptly by containing a greater amount of N₂. In spite of the change of these gas compositions the steel specimens imbedded in the sawdusts are carburized thicker in proportion to the charring time and temperature.
So it is probable that the CO gas,which is produced by the charred carbon around the surface of the steel specimens, carburizes the steel much and these gases as analysed exhaust gas do less when the heating time is prolonged.

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Instead of the sawdusts alone, the generated charring gases of the sawdusts mixed with 5%,10% and 20% of lime at the charring temperatures of 700°, 800° and 900° respectively, and also their carburizing characters at 925° were studied. The experimental results show that there is generated a much greater amount of CO in charring gases compared with tha t of sawdusts only. So the steel specimens imbedded in them are more powerfully carburized by useing lime mixed sawdusts.
Moreover, the influence of coke mixed with the sawdusts on the carburizing action at 925°, was studied and it was found that there is a nullifying tendency of the carburizing power of sawdusts by adding coke powders.

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It was found that the special zinc-cementation method proposed by the present authors has both merits of the so-called galvanizing and sherardizing. The method is to pack the iron in the powder composed of 3∼10%Zn, 97∼90%Al₂O₃ or MgO and to heat it to above the melting point of zinc, 500∼600°C, for less than an hour. The authors postulate that the coating is formed by the gaseous penetration as well as by the solid diffusion of zinc into the iron. The effects of zinc content in the powder (from 3% to 90%Zn), heating time (from 1 hr to 5 hr), and heating temperature (from 450°C to 850°C) on the nature of coatings were studied : the greater part of the coating, the outer portion, is a layer consisting of zinc solid solution containing a small amount of iron, and the inner layer is ζ phase based on FeZn₁₃, δ₁ phase based on FeZn₇, or Γ phase based on FeZn₃ as the heating temperature is raised. The thickness of the coating is 0.05 mm to 0.1 mm on heating at the temperature range of 450°C∼600°C for an hour. The cohesion of the coating was studied by dropping a 1.3 kg weight from 10 cm height fifty times repeatedly on the coated articles and measuring the weight change. The corrosion of these articles in the NaCl solution and in the air were also examined, and the result was compared with that of the galvanized or the sherardized articles. The durability of the formers were superior to that of the others.
Merits in this special method are as follows :—
(1) The treating time becomes shorter than that of sherardizing, since heating temperature is at above the melting point of zinc.
(2) This method may be applied for the machine articles finished, without seriously changing their dimentions.
(3) The uniformity and evenness of the coating were obtained.
(4) There is no fear of the powder coking,in spite of heating at above the melting point of zinc,since little zinc is contained in the powder, and can be used repeatedly by adding a small amount of fresh zinc.

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