The present authors observed oxide films and scales produced on the surface layers of Fe-Si-Cr system alloys (about 1 to 7% Si, 5 to 19% Cr), heated in air at high temperatures (700° to 1200°C), using the transmission electron diffraction method, the X-ray diffraction method and a metallurgical microscope. It was verified that 3 to 7% Si-Cr-Fe system alloys are covered mainly with Cr₂O₃ or α-(Cr, Fe)₂O₃ crystal films in the early stages of oxidation at 700°C and 1000°C (Table 1). It has already been reported that amorphous SiO₂ films can be detected on the surface of 1 to 6% Si-Fe system alloys at 700° to 1000°C as a result of oxidation, but this kind of oxide film has not been observed on the surfaces of 1 to 4% Si-Cr-Fe system alloys heated in air under the above conditions. The present studies also clarified experimentally that the heat-resisting films of Fe-Si-Cr system alloys oxidized in air at 1100° and 1200°C for 7 hours are composed of fine Cr₂O₃ crystals (Table 1).

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The present authors studied, using the transmission electron diffraction method, initial oxide films of A.I.S.I. Type 302 B (2.45% Si), 19-9 DL (0.50% Si), Durimet 20 (1.27% Si) and Nichrome (JIS No. 1, 0.5-1.5% Si) oxidized in air at 700° to 900°C. A solution of 1 cc Bromine and 50 cc Methanol was satisfactorily used for isolating the oxide films from these alloys. The electron diffraction patterns obtained from initial oxide films (700° to 900°C) of the alloys showed the existence of a rhombohedral type (mainly Cr₂O₃ or α-(Cr, Fe)₂O₃) and spinel type oxides, and no such special oxides as SiO₂ could be observed in the patterns. However, α-cristobalite crystals were detected when the films were heated at 1200°C for 1 to 3 hours. Thereby the authors clarified experimentally that the special heat-resisting films consisting of amorphous SiO₂ are formed on the surfaces of alloys in the earliest stages of oxidation.

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The temperature dependence of the electrical resistance of Alnico 5 specimens was measured at various temperatures. It was concluded from the measurement results that two different mechanisms operate during the aging process of Alnico 5. One starts from about 300°C and ends at about 600°C, and the other occurs above 650°C. The former mechanism is the one which gives the best magnetic property and may be considered as something like the order-disorder transition, while the latter may be precipitation.

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An investigation of magnetic properties of a MnO-ZnO-Fe₂O₃ ternary system, crystallized in various atmospheric conditions is reported in this paper. The initial permeability, maximum permeability, saturation magnetization, Curie temperature and hysteresis loop were measured for these ceramic ferrites. Also, the crystal structure of these specimens were examined by X-ray diffraction. It has been found that a high permeability region in the ternary system is markedly wider in the case of sintering in nitrogen than in air, because the excess hematite is reduced to magnetite in the region where the Fe₂O₃ content is more than 50 mol%. It has also been found that the line connecting the maxima of the initial permeability agrees with the lines of zero magnetostriction and minimum magnetic anisotropy and that manganese-rich ferrites sintered in nitrogen, exhibit a square hysteresis loop.

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The e.m.f. of the cell Tl(l)/TlCl in KCl-LiCl/Ti-Bi(l) was measured over the temperature range of 370° to 480°C. The activity curve shows a profoundly negative deviation from Raoult’s law. The excess thermodynamic functions were calculated from the activity data obtained. Theoretical consideration was given for the excess functions of this system.

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The grain growth after light rolling below 10% in grain-oriented silicon-iron sheets containing 3.50 and 1.43% Si was studied optically and magnetically in order to obtain fundamental data for the establishment of a strain-annealing procedure as a modification of the Goss process. It has been found that, in initially fine-grained sheet specimens, the grain growth increases more prominently at two reduction rates, namely, at 0.5 to 2% and 6 to 7%. Their resulting preferred orientations are different; in the former, a marked development of the Goss texture occurred, possibly involving no primary recrystallization, while in the latter recrystallization from the Goss texture also occurred.
The recrystalization from the Goss texture occurred also on initially coarse-grained specimens. It has been found that the optimum point for producing silicon-iron sheets with high permeability and low hysteresis loss is at the first grain growth maximum of 2% reduction for initially fine-grained sheet specimens.

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In this paper the authors have tried to make clear the tempering process of 0.4% C-steel after quenching by means of electron micrography. The authors also used X-ray diffraction methods and thermal analysis as an aid to interprete the electron micrography. The results, make clear the details of the transformation of ε-iron carbide to cementite, the existence of the platelet cementite at a former stage of the precipitation of cementite and the relationship between the shape of granular cementites and the sub-boundaries on the grain-growth of the granular cementites.

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The present study was made in an effort to make various tests on the electrolytic isolation of sulfide from steel and to examine the value of this procedure. Further experiments based on this procedure were made to ascertain the inherent properties and the occurrence of sulfide phases in low-carbon alloy steels. The results show that the Sodium Citrate method is applicable to the isolation of sulfides from steels containing Manganese, Vanadium, Niobium, Titanium and Zirconium. The Hydrochloric Acid method is suitable for the electrolysis of Chromium steels. The sulfide in Aluminum steel is decomposed by aqueous solutions and can not be isolated electrolytically. The microscopic examination of isolated residues is found to be effective as a method for revealing the three dimensional shapes of sulfides. Chemical and X-ray analyses of isolated sulfides indicated that the alloying elements in steels may be divided into three groups according to their sulfide forming tendencies as follows: (a) Zirconium, Titanium, Manganese and Niobium are strong sulfide formers. (b) Vanadium and Chromium are medium sulfide formers. (c) Cobalt, Nickel, Molybdenum, Tungsten and Silicon are weak ones.

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Methods for preparing Mn-Bi and Mn-Al alloys and producing magnets from Mn-Bi alloys have been studied. A Mn-Bi alloy of high purity was prepared by sintering powders of Mn and Bi at 260°C for about 1000 hrs. Ferromagnetic Mn-Al alloys were prepared by quenching and tempering, and the influences of the temperatures of these treatments on the magnetic properties of the ferromagnetic Mn-Al alloy were studied in detail. To pulverize the Mn-Bi compound a hammer mill was used in an Argon atmosphere, and this gave good results. Mn-Bi magnets were produced by compressing power containing about 8% of resin at 200°C, and curing at 100°C. To obtain good magnetic properties, the magnetic field applied during compression should be 9,000 Oe or stronger. A magnet thus prepared has a Br of 2,500 to 3,800 gauss, and a _BB_C of 1,200 to 2,600 Oe. The thermal coefficient of remanence was about −1.23×10⁻³ gauss/°C.

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The annealing of iron-chromium alloys containing more than 40 percent chromium at 600°C, and above where the so called 475°C brittleness is not observed, causes the shift of the magnetic transformation temperature to a somewhat higher temperature. In order to clarify this phenomenon, the measurement of thermomagnetic behavior, hardness, thermal expansion, and magnetization-curves and observatioms of microscopic structures were made on iron-chromium alloys heat treated in several ways. It is known that this phenomenon is not due in the formation of the FeCr superlattice but is explained by the precipitation and resolution of chromium compounds such as chromium carbide.

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Observations were made on the fatigue fracture surfaces of low alloy steels, high carbon steels and also some other alloys, using a fatigue tester of the rotating beam type and employing the electron microfractograpic technique. The results obtained are as follows:
(1) The fatigue fracture surfaces of low alloy steels quenched and tempered, were classified into five types as in the case of low carbon steels, as reported in the author’s 1st report.
(2) The fracture surfaces of hardened carbon steels (0.6% carbon) did not show the characteristics of a typical fatigue fracture, but a river pattern was observed which ordinarily appears on a brittle fracture surface.
(3) In the case of high carbon steels in an annealed state the patterns observed were of a lamellar pearlite like structure on the fatigue fracture surface. The surfaces, however, had not been treated with any etchant. Parts corresponding to ferrite had the structure of fine stripes spaced at less than 200 Å, while parts corresponding to cementite were smooth and flat without any signs of a pattern of stripes.
(4) The parallel patterns were observed principally on the fatigue fracture surfaces of 13% Cr steel, 18-8 austenitic steel and 6-4 brass.

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When solid metals are melted, the crystal structure breaks down, and the atomic arrangement becomes entirely random. It is presumed that when metals are in a molten state valence electrons, moving about in an irregular potential field due to the random distribution of ions, behave as free electrons. As one of the experimental methods for examining this hypothesis the measurement of the Hall coefficient of molten metals was undertaken. High purity Cd In, Sn, and Bi were used for the measurement. All of these, metals showed negative Hall cofficients independent of temperature in the molten state and the measured Hall coefficients were in good agreement with the theoretical values calculated under the assumption that in molten metals all of the valence electrons of the atoms contribute to the conduction as free electrons.

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In the author’s previous report, it was presumed that in the electronic structure of metals in the molten state that valence electrons of atoms of metals behave as free electron gas. To examine such an assumption the magnetic susceptibilities of molten metals and molten alloys were measured in wide ranges of temperatures and results were compared with theoretical values computed on the basis of the free electron gas model. An extremely sensitive apparatus was devised for measuring very weak magnetic susceptibilies of molten metals. Pure metals used in this experiment were Ag, Cd, In, Sn, Bi and Sb of 99.99% purity or higher, and the alloys used were Bi-Ag, Bi-Cd, Bi-In, Bi-Sn, Sn-Pb and Pb-Sb.
It was shown that observed magnetic susceptibilities were always independent of temperature in pure metals and also in alloys, and were in good agreement with the calculated values given by the sum of the paramagnetic susceptibility contributed by the free electron gas and the diamagnetic susceptibility of the ion cores.

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