In order to eliminate maximum in the hardness-time curve of Corson alloy aged at 500°, an attempt is madee so that the matrix of solid solution may be made more viscous by an addition of elements. As the adding elements, Al, Fe, Co and Cr were selected, the amount for Al being 1_??_10% and others for less than 5% each.
Although the object can be attained to a certain extent by a mere addition of Al, further improvement was made by additions of Fe and Co besides Al. Cr was not as much effective as was Fe and Co. Those alloys, which do not show the maximum by ageing at 500°, also showed the maximum by ageing at 550°. This phenomenon seems, to play an important role in the age-hardening theory, but it will be related in a later paper and here are given only mechanical properties of Corson alloy and modified Corson alloys by Fe or Co, an example of which is given below:-
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The deoxidizing powers of metals can be calculated, besides direct measurements, from thermodynamical values of their oxides in the solid state. By this calculation method, J. Chipman proposed the deoxidizing power of numerous metals which were not obtainable by an experiment. However, he did not indicate the reliability of his results calculated. Since thermodynamical values of manganese and its oxide in the solid state are known with a fair degree of accuracy and may be accepted with confidence. the writer calculated the equilibrium constant in the reaction by which dissolved iron oxide is removed from molten iron by manganese and obtained the results in good agreement with those of the direct measurements. Thus it is inferred that deoxidizing powers of metals estimated by the thermodynamical calculation method are generally as reliable as those by the direct measurements.

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As a supplement of the former experiment on the research for acidresisting alloys of nickel-base against hydrochloric acid under following conditions; in 20 percent and 10 percent boiling condition, in 30 percent, 20 percent and 10 percent solutions at room temperature, the writers carried out further experiment for perminvar and 13 kinds of nickel-base alloys newly prepared, which can be easily cast and forged except Nemiftacle and Nemiftacle C alloys. In this experiment, resistivities of newly prepared alloys against 20 percent sulphuric and nitric acids and 10 percent ferric chloride solution were also studied. According to this experiment, the resistivity of Nemic alloy in 10 percent and 20 percent solutions on boiling condition was much better than that of Nemif C1 mentioned in the former report [J. Iron and Steel Institute of Japan, 23 (1937), 573], and resistivity of the former alloy in 20 and 30 percent solutions at room temperature was also comparable with that of the latter, but in 10 percent solution at room temperature, it was not so good as those of Nemicle C, Necomicle which have high degree of resistivity. The next best in resistivity on boiling condition was those of Nemiw and Nemiw C alloys, which were better than Nemif C1, but comparable under condition of room temperature. The alloys contained 30 percent Mo or Mo+W and no Cr such as Nemic, Nemiw, Nemiw C and others, have high degree of resistivity, against concentrated bydrochloric acid at room temperature and in solutions of various concentrations on boiling condition; however they are easily attacked by oxidizing acidic solutions. In general, those nickel-alloys containing 30 percent Mo or Mo+W are hardly cast and forged, but the alloys described in this experiment were cast, forged and rolled with a precaution, as shown in Photograph. It is also confirmed in the experiment that the alloys containing more than 15 percent Cr and 7 percent Mo have generally a good resistivity against the acidic solution which contains an oxidizing agent, for instance, ferric chloride, nitric acid or dilute hydrochloric acid with dissolved oxygen. The appearance of specimens of various alloys attacked by hydrochloric acid on various conditions and other reagents are shown in photographs.

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Many steel core-rods containing one of elements, cobalt, molybdenum, copper, nickel, tungsten, vanadium, silicon, titanium, aluminium, carbon, manganese or chromium, were made, on whichh a flux consisting of 70% CaF₂ and 30% Ca(OH)₂ was coated. Using these electrodes single V butt joints of mild steel were made, and soundness of the welded joint was examined by the X-ray and microscopic methods, and apparent specific gravity of the deposited metal was measured by the immersion method. By these experiments the following results were obtained. As the content of deoxidizer, such as vanadium, manganese, silicon, titanium, aluminium or carbon increases in the core-rod of coated electrode, quantity of blow holes in the deposited metal decreases, but the quantity of non-metallic inclusions in it increases except in the case of carbon. In the case of coated electrades containing chromium or a large quantity of manganese in the core rod, many holes opening at the surface of bead appeared.
It is inferred that if a core-rod containing two or more deoxidizing elements properly selected is used the sound deposited metal containing less or no retained deoxidation product will be obtained.

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The single potential of pure Aluminium (99.99%) electrode was measured in aqueous solution of 1 N KCl, and was obtained Eh_??_-1.26V. In the measurement care was taken for the variation of potential in the outset and for the effect of gases, such as N₂, H₂ or O₂. The potentials of commercial aluminiums (99.8, 99.5%) and Al-Fe(5%) alloy were also measured.

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The relation between the grain size and mechanical properties of duralumin was studied. It is concluded that the tensile strength of duralumin decreases as the number of grain per unit area decreases, and the resistance to fatigue is also similarly deduced. The fine grained structure is obtained by either one of the following 3 methods.
(i) In cold extension, its percentage must be less than 2 or greater than 10.
(ii) In hotforging greater the percentage of reduction and lower the temperature of forging, finer the obtained structure.
(iii) Increase the percentage of manganese up to 1.2.

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The ageing of super-duralumin (RF1 Cu 4.01%. Mg 1.77% and RF 2 Cu 4.09% Mg 1.12%) and Al-Cu alloy (Cu 2% and 4%) was investigated by X-ray back reflection focussing method using Cu K_a radiation. The quenched specimen was fixed on an X-ray camera and incident X-ray beam was adjusted so as to illuminate the same part of the specimen always from the same direction. Photographs were taken immediately after, quenching, 15min., 30min., 1 hr., etc. and obtained following results. Some of the spots reflected from (511) planes of super-duralumin change their shapes by internal strain or bending of the crystal grains during ageing and this continues for several hours. At first, the change in the position of the spot is rather at random but finally it displaces to the side of larger-lattice constant. The mean dilatation of the lattice after 20 hrs. was 0.0121% and 0.0274% respectively, for RF1 and RF2, while the lattice constants immediately after quenching were 4.036 and 4.035 A. U. Above result confirms that of Nishinmra⁽¹⁾ who found that the natural ageing of super-duralumin is mainly concerned to the formation of ternary compound S or CuAl₂. Regarding dilatations of the lattice the present author already observed in the case of duralumin⁽²⁾. According to Nishimura's ternary diagram the formation of CuAl₂ will also take place in RF2, and therefore the dilatation of the lattice of this alloy is larger than the other. The change in the shape of the spot and the displacement of its position is not so remarkable in Al-Cu alloy, but in some alloys having 4% Cu, bending of the atomic plane during ageing was very noticeable; the tendency of lattice dilatation was also observed.

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