In the present paper, different kinds of high permeable alloys invented both in abroad and home were described, and a theory of high permeability was put forwards. Alloys of constant permeability was also described. Lastly a description regarding alloys used as permanent magnets, such as K. S. magnet steel, M. K. magnet alloy, Kato's sintered magnetic alloy and New K. S. magnet alloy, was given together with the theory of high coercive force. As a support of this theory, an interesting fact was observed that pure iron which was specially treated, showed a high coercive force as high as 150 Oersteds.

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The constitutions of the Al-rich alloys containing Cu and Mg were investigated by means of thermal analysis and microscopic examination. ation. From various constitutional sections taken as constant in Al-content or taken through the Al axis, the following conclusions were drawn: (1). In a range of Cu 50% and Mg 40%, the primary separations are (Al), CuAl₂, S, T, β and X, where S and T being in equilibrium with (Al), denote ternary compounds Al₁₃Cu₇Mg₈ and Al₅CuMg₄ respectively, β is an intermediate phase existing between Al and Mg and X is an unknown phase not determined in this investigation. (2). The ternary compounds Al₁₃Cu₇Mg₈. and Al₅CuMg₄ were found to exist. (3). The uni-variant reaction lines were found to be: -Liq_??_(Al)+CuAl₂, Liq_??_(Al)+S, Liq_??_(Al)+T, Liq_??_(Al)+β, Liq_??_CuAl₂+S, Liq+T_??_S, Liq+X_??_S, Liq+X_??_T, Liq_??_T+β, and the in-variant points were; Liq (Al)+CuAl₂+S, at 500°, Liq_??_(Al)+T+β, at 447°, Liq+S_??_T+(Al), at 465°, and Liq+X_??_S+T, at 525°. (4). It is concluded that the natural ageing of Duralumin and 24S-type Super-Duralumin is mainly concerned with the solid solubilily change of S-compound and CuAl₂ or that of S-compound in Aluminium.

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A new equilibrium diagram of the system Cobalt-Copper based on the results of the following methods has ben proposed: total, differential, as well as newly devised thermal analyses, magnetic and electrical measurements, dilatometry, microscopy and X-ray analysis. The results of the investigation are summerised as follows: (1) Primary crystallisation points lowers with the increase of Cu to the peritectic temperature 1112°, The compositions of β and γ solid solutions and liquid phase at the peritectic temperature are 12.8, 92 and 95.5% Cu respectively. (2) There is no monotectic reaction, that was suggested by Konstantinow; Co and Cu foam a homogeneous liquid in all mixtures. (3) The solidified alloys are composed one or two of the following three phases, i.e., α-Co, β-Co and y, the latter being the Cu-rich solid solution (4) The α-β allotropic transformation point of Co lowers with the increase of Cu, and at 10.2% Cu and 342° a eutectoid reaction occurs. (5) The lattice constant of a and S cobalt becomes larger with the addition of Cu, but the increasing amount is very small. The lattice constant of Cu-rich solid solution, on the contrary, becomes smaller with the addition of Co. (6) At room temperature the solubility of Cu in α-Co is 9.4%, while that of Coin Cu is 0.3% (7) The magnetic transformation point in S-Phase lowers with the addition of Cu down to 12.2% Cu and 1065°. (8) The X-ray analysis of an alloy of 95% Cu does not indicate any occurrence of peritectoid reaction, which was suggested by Sahmen. This fact was also confirmed by magnetic analysis.

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(The synopsis covers the work of I & II inclusive; II will appear later.) The catalytic action of alkali and alkaline earth carbonates upon the reversible reaction 2CO_??_C+CO₂ was experimented together with catalysers other than carbonates, namely fine particles of Fe, Ni, Co and Cu. It was found that the principal cause of the catalytic action of these carbonates is not due to the thermal dissociation MCO₃=MO+CO₂ as has hitherto been considered, but to the same action as that of metallic catalysers, Ni, Co, Fe and Cu, previously studied. The catalytic action of carbonates is considered to be due to the adsorption of CO gas forming an intermediate compound with the metallic radical of the carbonate, as in the case of metallic catalysers, thus
2MCO₃+6CO=2M(CO)₂+4CO₂
2M(CO)₂=MO+MCO₃+3C
MO+CO₂=MCO₃
In all alkali and alkaline earth metals, the existence of its carbonyl, M(CO)₂, was confirmed; the catalytic action of its carbonate such as K₂CO₃, Na₂CO₃, BaCO₃ and SrCO₃, is also active, the feebleness of the catalytic power of CaCO₃ being ascribed to the doubtful existence of Ca carbonyl. Judging from the theory of solid catalysers in gas reactions, CO gas that clings to carbonates is considered to exist highly activated condition, and thus all the reations in Fe-O-C csystem are greatly energized, such as the cementation of iron and steel. The metals that form carbonyls, viz., W, Cr and Mo were similarly proved to be active in accelerating the reactions 2CO=C+CO₂ and 3 Fe+2CO=Fe₃C+CO₂.

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On a stress-strain diagram obtained by repeated load tests, the following conclusions were drawn:- (1). Mechanical properties of test materials, such as yielding point, breaking stress, etc. can not directly be determined by loaddeformation diagram or an outer moment-angle diagram as in the case of statical test. (2). A stress at any point in the test piece for repeated loading can be determined from the following three factors: (i) a load or an outer moment including its acceleration, (ii) the frequency of load or the outer moment above mentioned, and (iii) characteristic properties with respect to the natural vibration of the test piece.

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According to the theory on the cause of temper-brittleness in steels introduced by Profs. Honda and Yamada, the phenomenon is due to the presence of the carbides separated on the grain boundaries along the solubility line below the Al point. Several observed facts connected with the temper-brittleness can satisfactorily be explained by the above theory although there is no definite microscopic evidence for the boundary carbides in brittle specimens. The age-hardening in alloys by heat treatment is also closely connected with the change in solubility in solid solution. The two phenomena, therefore, are related to each other with respect to the solubility change in solid solution; hence steels susceptible to temper-brittleness should show the ageing phenomenon and age-hardening alloys should have a property similar to the temper brittleness in steels, In this view, the temper-brittleness in steels can be dealt with as a property common to all metallic alloys with varying solubility in solid solution, In some of these age-hardening alloys, the mechanism of temper-brittleness in steels can favourably be studied by the reasons that (1) microscopic observations of the existence of compounds on the grain boundaries are possible, (2) the physical properties of such solid solutions are comparatively well known. In the first part of this investigation, the existence of both temper-brittleness and age-hardening was first confirmed in 3 carbon steels, 7 nickel-chromium steels, chromium steels, nickel steel, Duralumin, aluminium-copper alloy containing 5.5 per cent. copper, 18-8 stainless steel and Corson alloy containing 4 per cent. Ni₂Si by means of impact and hardness tests. The effect of the boundary compounds on the impact values of these alloys was then examined microscopically as well as mechanically on these nonferrous alloys and also on 18-8 stainless steel subjected to several kinds of heat treatments. It was concluded that the cause of the brittleness in these materials is due to the presence of the compounds on the grain boundaries. Thus the carbide theory on the temper-brittleness in steels was experimentally confirmed. In the second part of the investigation, the effect 'of the presence of solid solution-phases separated out on the boundaries of the crystal grains on the mechanical properties of the alloys was examined also microscopically as well as mechanically on the age-hardening alloys, such as copper-iron alloy containing 1.31 per cent. iron, copper-silver alloy containing 4, 81 per cent. silver and iron-copper alloys containing about 2 per cent, copper. It was found by the experiments that there are two kinds of age-hardening alloys with or without the properties similar to the temperbrittleness in steels, depending on the relation between the hardness of a phase separated out on the grain boundaries and that of the ground mass of the alloys; i.e. the copper iron alloy with harder phase on grain boundaries is the former case, while the copper-silver or iron-copper alloy with softer phase on grain boundaries the latter. From these results, the general elucidation on the change of the properties in the age-hardening alloys caused by heat treatments was given.

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