The hardness of forged iron-cobalt alloys which were annealed and quenched, has been measured by Rockwell hardness tester in B-scale.The hardness value of the alloys in the FeCo superlattice range from 40 to 60% of cobalt changes due to the order-disorder transformation. The hardness value in B-scale of 51.5% cobalt alloy (FeCo) is 91 in the quenched state, while 76.5 in the slow-cooled state ; the change of hardness value being about 19%. The hardness changes remarkably between 650° and the transformation temperature (732°).

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The results which are obtained from the consideration for the known experimental results of the natural agehardening phenomenon of Al-Cu alloys are as follows : Assuming that the exceptional distribution state takes place in the thermal vibration energy being possessed when specimens are quenched,Cu atoms at this district can displace the position in the crystal lattice under the temperature at which the ordinary diffusion occurs and this phenomenon is not on the way of the precipitation, but the special course according to the existence curves.
(1) Atoms at this particular district need less activation energy [ω−F(λ)] than that for the self-diffusion (ω) and F(λ), function of the distance (λ) from the nucleus of migrates, is decreasing in proportion to λ.
(2) The displacement of atoms in this range turns to the center at which F(λ)is the largest.
(3) Assuming that it needs the activation energy (U) when the nuclei ccur, the out-breaking numbers are generally proportional to e^−U⁄kT but in this case the nuclei occur nearly at the position which F(λ)_λ=0 is comparatively high.Then this probability is in proportion to the supersaturated Cu atom concentration, moreover F(λ)_λ=0 is affected by the conditions of quenching and the concentration of solute atoms.
(4) Supposing the activations energy for the mutual exchange between quenching and aging state as a and θ,ratio of the number of nonmigrated atom’s n₂ to that of the migrated n₁ is calculated from the following formula :n₁⁄n₂=ke^{(θ−ε)⁄kT}, aging velocity V=KN_s^ae^{−(w−F₀)⁄kT}·e^−ε⁄kT,and the hour until finishing of this phenomenon t=gN_s^−be^{(w−F₀)⁄kT}. Here, F₀ is the mean of F(λ) from the nucleus of migration to the farthest point within the migrationable limits and N_s the supersaturated concentration of Cu atoms.

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One of the authors reported in the second paper on the study of the mechanism of recrystallization in metallic crystals that there are discontinuous jumps in the process of deformation of crystals of pure iron at temperature of 650°C, pure nickel at 745°C, magnesium at 600°C and zinc at 300°C.
Then, the nature of such discontinuous jump in the creep process of single crystal of pure iron is studied under the following cases ; Influence of temperature to the magnitude and frequency of jumps. Influence of the existence of oxided surface layer. Polycrystalline state. The results are as follows ; The discontinuous jump occurs above the recrystallization temperature. The frequency of jump decreases with time at constant temperature and the magnitude of a jump increases with the rise of temperature. The oxided surface layer prevents the presence of discontinuous jump. In the polycrystalline state, the discontinuous jump does not occur apparently.

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Mg is added to pure Fe-C alloy which contains 4.15% of C and 0.023% of Si, or to ordinary cast iron, then the cooling curve and microstructure of these alloys are studied and discussed. Mg suppresses the supercooling of both eutectic reaction, Fe-C and Fe-Fe₃C. Ledeburite appears when Mg is added a little too much, but this disappears by an addition, of Si,especially an addition after Mg. Nodular graphite caused by addition of Mg is formed as an eutectic reaction from melt same as flaky graphite in normal cast iron, and for this formation the effect of Mg as gas state must be considered.
High C or Si is necessary to produce nodular graphite in ordinary cast iron and S prevents its formation.

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The experiments concerning the effects of melting and casting conditions on the casting structure were studied with pure zinc. Grain size was determined by numbering the grains in the constant area of casting which was macro-etched. following results were obtained.
1. At constant casting temperature,grain size becomes larger with elevation of the maximum heating temperature of melting, and rapid decrease in the grain size occurs when the maximum heating temperature exceeds 800°C.
2. If the maximum heating temperature has been maintained at a lower value, the longer the holding duration at this, the larger is the grain size, and after the holding duration exceeds 2 hours grain size becomes small.
3. The higher the casting temperature, the larger is the grain size, but grain refinement is produced if the casting temperature has exceeded the critical value of 600°C. The longer holding duration at the casting temperature results in the coarse grain.
4. The higher the temperature of mould, the more the tendency for coarse grain to produce is.

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The effects of the various factors in carburizing conditions on the carburization of Th-W filament were investigated by the method of “Hydrogen Carburization” heated in hydrogen gas flow mixed with carburizing gas such as benzene. To know the degree of carburization, the measurements of the cold electric resistance and the microscopic investigations were carried out. The amount of carbon diffusing into W in hydrogen atmosphere increases parabolically with elapse of time at constant temperature, but generally, the degree of carburization obtained by the microscopic study is at variance with the one obtained by measuring cold electric resistance. Under the influence of the convection in the carburizing atmosphere, the thickness of the carbide layer on the filament is not uniform. The effect of the concentration of benzene is smaller than the one of the speed of hydrogen gas flow. From the results above mentioned, the filaments with the uniform thickness of carbide layer were obtained by us.

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From the result in the 1st report, we found that it was suitable to adopt the range of 2.45∼3.16% as the carbon content in the carbide layer. Theoretically, we led the following formula representing the relation between the degree of carburization (S) and the ratio of increase in cold electric resistance (λ), λ=\cfrac11-S \left(1-\cfracρ_Wρ_W_2C\ ight)\labeleq1
where ρ_W and ρ_W2C are the cold electric specific resistances in the uncarburized core and the carburized sheath.
If the carbide layer is all of W₂C composition, the value of ρ_W⁄ρ_W2C is 0.07, but ρ_W⁄ρ_W2C is experimentally about 0.3 . The operating temperature of the carburized filament is not directly determined , because the total emissivity of W₂C has not been correctly found heretofore, so that using the actual data in the transmitting tube working, the following formula was theoretically determined. R_θ=fo \cfrac1-S \left(1-\cfracρ_Wρ_W_2C\ ight)1-S \left(1-\cfracρ_W(T)ρ_W_2C(T)\ ight)\labeleq2
where R_θ f_θ is either the ratio of the hot-to-cold electric resistance in a Th-W filament carburized, or not respectively, and ρ_W(T), ρ_W2C(T) is ρ_W,ρ_W2C at operating temperature T respectively. At any time, the degree of carburization is obtained from the formula (1)by measuring the cold electric resistance and the operating temperature of the carburized Th-W filament is known from the formula (2). The expansion of filament by carburization is increasing as ThO₂ content in W is decreasing, but the amount is negligibly small.

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This experiment was carried out to see how the molten metal flow and fill the sand mould. Fine wire of high electric resistance was inserted in mould space, and let the metal flow along this wire. The metal flow brings the change of wire resistance which can be recorded on a rotating drum using Braun tube oscillograph. For Al sand casting the results are as follows :
(1) Velocity of molten Al in sand is a little affected by moisture, and is largest at 9% moistedsand. (2) The velocity is largest when casted at 750°. (3) In ordinary case, flow of metal is affected by the dimensions of runner and gate. (4) Riser leads the metal faster and more uniformly, and without riser, the metal flow is affected by packing of sand. (5) Bended runner loses the metal velocity according to its bending angle.

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The authors have observed, in the previous paper [this journal, 6 (1942), 27] regarding the running quality of binary aluminium alloys containing silicium up to 15.69%, the following experimental results that the silicium content of the alloy, taking the minimum value of the running quality is between 3% and 4%, and that this content is higher in silicium than the composition of the maximum solidification temperature range and that the running quality of the hyper-eutectic alloy containing 15.69%Si is far more than that of the eutectic alloy. These phenomena could not be explained by using the solidification range theory of the running qaulity of alloys brought forward by A. Portevin and his collaborators. Therefore, the authors have studied the microscopic structures of the cross sections of the running quality test specimens and have confirmed that it is necessary to take into consideration the super-cooling phenomena in the solidification process of molten alloy flowing in the test mould for clarifying the nature of the running quality. Then, the phenomena above mentioned are reasonably explained as follows : the degree of the super-cooling of the hyper-eutectic alloy containing 15.69%Si is far more than that of the eutectic alloy and as the authors have poured the molten alloy into the test mould at about 50° above the liquidus temperature on the equilibrium diagram, the difference between the pouring temperature and the temperature of the primary crystallization of the hypereutectic alloy is more than that of the eutectic alloy. Consequently,the time interval where the perfectly liquid alloy flows in the test mould in the case of the hyper-eutectic alloy is far more than in the case of the eutectic alloy and the length of flow of the former alloy filled up the test mould is longer than that of the latter. The phenomenon that the running quality of the alloy containing silicium between 3% and 4% takes the mimimum value has not been sufficiently clarified by means of the microscopic study only, but it has been suporsed that the degree of the super-cooling of the alloy containing 3% and 4%Si is less than that of the Si 1.6%-alloy, and consequently this phenomenon takes place.

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In the proceeding reports we described that the mechanical properties and the corrosiveness of Al and its alloys are influenced by the occluded gases.
In the present report we are able to make it clear that there also is a difference as regards the fluidity between the gas-occluded molten Al and its alloys, and those which are not occluded,by our newly devised apparatus. That is to say, the decrease of fluidity with the increase of absorbed hydrogen is recognised, but the Eötvös’es law is not satisfied.
In this case the fluidity which is adopted in our experiment is indicated by the number of the drops of the molten metal, taking into consideration the following conditions, to which no attention may have been paid in the casting method in a spiral mold, such as(1)the surface tension between the molten metal and the grooves of the mold, (2)the edge effect of the flow, (3) above all, the oxide film of the molten metal.
Besides, the following formula is established \[n=Kx\frac1m\]
Where n: Number of drops ; m: Mean weight of drops ; K : Proportional constant ,

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Repeated melting secondary aluminium shows better fluidity, casting property and resistance to corrosion, but little better mechanical properties.
To give an answer to this question, the authors have found decrease of nitrogen content. In this paper the results of these tests are discussed.

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In order to improve the corrosion resistance of steel, it was coated on its surface with arsenic film.Coating was made by cementation method and thus prepared samples were immersed in various acid solutions. According to the results it is generally considered that arsenic coating steels have the strong corrosion resistance to acid solutions except concentrated solutions of hydrochloric acid.

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A special counter tube is devised for the determination of K in silumin. The form of the tube is shown in Fig. 1-(b),the dimension being 15 mm in diameter, 0.13 mm in thickness and 30 mm in the length for duralmin. After machining it to the desired form, this tube was inserted into the glass bulb with high tension added Pt wire, which was connected from one side to the other side of glass tube. Then the tube was enclosed with a mixture gas of anhydrous alcohol and argon. As the arrangement of the circuit is shown in Fig. 2,the main circuit consisted of three parts, namely stabiliser circuit,amplitude cirsuit and counter. In order to avoid the slight change of primary source of A.C.on the high tension side, which seemed to have instantaneous change on the counter, the form of series connection with 200 V neon lamp was adopted in our experiment. For the purpose of determining K in silumin, the above mentioned apparatus was used and satisfactory results were obtained by authors.

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In this paper, the simple, accurate and rapid method for the determination of Cu in Sn-base alloys, is explained.
Cu is determined from HNO₃-HF medium by the internal electrolysis, using a lequid Pb-Hg as an anode.
In this experiment, Sb⁺⁵,As⁺⁵,Sn⁺⁴ and Zn⁺² do not interfere. Sb and As should be oxidized prior to the electrolysis. Sn is changed into the state of Sn⁺⁴ when the sample is dissolved in a Pt-dish by the procedure given. If the sample contains Bi,it is deposited with Cu. In such a case,Bi is removed from the solution, obtained by dissolving the combined deposits with HNO₃ and Cu is replated from the filtrate as in the preceding procedure. Ag is also plated with Cu. After dissolving the combined deposits, the determination can be completed by determining Ag by the re-deposition from the solution, acidified by H₂SO₄, and getting Cu by difference.

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A direct method of iodometric determination of ferric iron in slags has been studied. Under the conditions of the procedure recommended, especially by the addition of about 5 g of KI, the necessity for warming the solution after the first end point and then retitrating had been eliminated, and best results were obtained rapidly in about 10 minutes. Our procedure will offer far more simple and rapid direct method of estimating the content of ferric iron in slags than the usual method in which each content of the total iron and the ferrous iron are respectively determined and from the difference between these two contents the content of the ferric iron is determined.

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Much has been written in the literature concerning the determination of oxygen in iron and steels, but it seems to be desired that more study should be made on the accuracy,speed and ease of manipulation. Several years ago,one of the interesting methode,the so-called “nitrogen fusion method” was proposed by L.Singer. In this report, the results found on the examination about this method are given from the point of view as noted as above.

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The amount of error caused by reducing effect of sulphide on ferric iron in determining FeO in slags and iron ores was examined and estimated with the artificial sample prepared by mixing FeCl₃ solution and CaS or MnS. The results obtained showed that the error was proportional to th e amount of sulphide sulphur and ferric iron contained in the sample, but was almost to the kind of sulphide. These results having been applied to actual samples, the error included in the analytical value of FeO was found to be less than about+2% at most in the case of ordinary basic open-hearth slags which were low in Fe₂O₃ and sulphide sulphur content, but amounted to 7∼70% in the case of pyrite cinder and some iron ores which were relatively high in Fe₂O₃ and sulphide contents, except for such special case as gumma ore in which the content of HCl-soluble sulphide sulphur was nearly zero and therefore the error in FeO value might be considered to be zero.

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