Dendritic segregation of a 20 ton acid open-hearth nickel-chrome steel ingot was studied. Thin sheets of 1mm thickness weighing 1kg were cut off from the roughly forged ingot, polished and etched with special macro-etching solution. Chemical analyses were made with this solution and contents of the alloying elements in the dendrite skelton were calculated by balance of the weight before and after the etching. Surfaces of the specimen deeply etched, were field off and the chemical analyses were made with the filing. The results obtained are as follows:
C (%) Ni (%) Cr (%) Mn (%) P (%)
Ladle analysis…………0.26 3.40 0.78 0.57 0.028
Analysis of the sheet………0.28 3.38 0.87 0.52 0.030
Dendritic slekton…………0.31 3.16 0.74 0.58 0.025
Inter dendritic filling………0.28 3.49 0.94 0.51 0.047

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An X-ray investigation was carried out for the crystal structure of cobalt heated at temperatures above the transformation point, and it was found that the β phase of face-centred cubic lattice is retained more in the surface layer of about 0.02mm than in the interior, and also that the grain size is smaller in the former than in the latter, as is shown in Fig. 1 (Pl.), Fig. 2 and Table 1. In the case of annealed file powder, which should be markedly affected by the above surface phenomenon, the greater part of the powder was, as expected, of cubic structure.
In order to inquire into the cause of the above surface phenomenon, the same experiment as above was also made with very pure cobalt, but since the result was almost the same as before, the phenomenon does not seem likely to be attributed to the impurity in the specimen. By testing a specimen, which was etched to remove the surface layer affected by the cold work of machining and polishing, the above phenomenon was found to have been very much reduced. Therefore this phenomenon may be explained by the reason that the grain refinement in the surface layer due to a severe cold work before heat treatment slackens the trans-formation of cubic phase into hexagonal.
A specimen, the surface of which was polished after annealing was also examined by X-rays. The result was that the polished surface was entirely of hexagonal phase, while in the interior more or less quantity of the cubic was retained. This difference is evidently attributable to the stress due to polishing.
The surface phenomena as found in the present investigation call crystal analyst' attention to the fact that the surface layer does not necessarily have the same structure as the interior, especially for metals having a low transformation point or for those which easily super-cools. The uncertainty can of course be eliminated to a large extent by dissolving off of the doubtful surface.

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Two series of laboratory experiments were carried out to test the corrosive effect of 1% HgCl₂ and 10% FeCl₃ aqueous solutions on specimens of Fe-Cr alloys containing Cr 4.81_??_33.1%, C 0.02_??_0.04% and Fe-Cr-Mo alloys containing Cr 13.47_??_25.13%, Mo 1.75_??_6.94%, C 0.05_??_0.26% which were prepared by rolling and machining from the ingot.
The corrosion resistance was determined by measuring the weight loss on specimens exposed to the solutions at ordinary temperatures.
Results obtained shows that the corrosion resistance of alloys to the above solutions increases generally with their Cr content, and the effect of the resistance on Mo addition to the Fe-Cr alloys is remarkably favorable in the both corrosive media.

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The alloys of the ternary system copper-nickel-silicon are very useful industrially, such as Silicon Monel, Corson Alloy, etc., but the ternary system has not been studied systematically.
By means of microscopic examination and thermal, X-ray and dilatometric analyses the author has investigated the equilibrium state of the whole system, a part of which is reported in this paper.
Since γ phase of the copper-silicon system is formed on cooling by the peritectoid reaction κ+δ→γ at 730°, it does not maintain equilibrium with liquid, However, when nickel is added to this binary system, the γ phase dissolves nickel and forms a ternary solid solution, which crystallizes primarily on cooling from liquid containing nickel more than 2% by weight.
In general, for the requirement of the primary crystallization of a phase, which does not maintain equili-brium with liquid in a binary system, from ternary liquid on addition of the third constituent, the nonvariant reactions except the following one are not considered to exist:
remelting and eutectoid reaction s₁→L₁+s₂+s₃
or remelting and peritectoid reaction s₁+s₂→L₁+s₃
both on cooling, where s and L indicate solid and liquid respectively.
In the heterogeneous equilibrium of the ternary system containing small amount of nickel with respect to the liquid, the every remelting reaction as above shown does not occur, and the peritecto-eutectoid reaction β+γ_??_κ+δ (795°_??_793°, 1_??_1.3% Ni, 8% Si) can be presumed to exist from the behaviour of the monovariant reactions β_??_κ+δ and κ+δ_??_γ starting from the copper-silicon system,
The preceding experimental results with the theoretical consideration lead to the conclusion that γ phase is primarily crystallized without such remelting reactions from ternary liquid.
The process in which the primary crystallization of γ phase takes place is as follows: - in Fig 13 (quanti-tative diagram) or in Fig. 18 (qualitative diagram)
L+α+γ_??_β……T₁' point (858°, 89.5% Cu, 2.5% Ni, 8.0% Si)
and L+β+γ_??_δ……T₂' point (835°, 89.0% Cu, 2.0% Ni, 9.0% Si)
In these reactions, when L is consumed, β→α+γ for the former and β+γ→δ for the latter on cooling. The monovariant curves β→α+γ and α+β→κ meet at B₂', where the monovariant reaction α+β→κ+γ occurs. If β, κ and γ are in coexistence after the completion of the latter reaction, the reaction of β→κ+γ takes place. The reactions B→κ+γ and β+γ→δ form the following reaction, [β]_B3'+[γ]_C4'→[κ]_J2'+[δ]_D5'……B'₃ point (795°_??_793°, 1_??_1.3% Ni, 8.0% Si) When γ is consumed in the preceding reaction, β→κ+δ may take place, and if β be consumed κ+δ→γ occurs, and these two monovariant reactions fall into the respective nonvariant reaction in the copper-silicon system.

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The alloys containing Cu and Mg in the proportion 4:1 to 2:2 and Zn were prepared and the effects of Zn upon the ageing properties of these alloys in chill-cast or rolled conditions were examined.
The alloys containing Cu and Mg in the proportion 4:1 or 4:1.5 were found to age-harden well at the room temperature, even if Zn is added, but the alloys containing Cu and Mg in the proportion 2:1.5 or 2:2 were observed not to age-harden so much as the former, and they showed somewhat a tendency of incubation. These alloys, however, were markedly hardened by tempering at 150°.
To ascertain these diffences of ageing phenomena between these alloys, differential dilation curves were obtained on the quenched alloys. The irregular change of the dilatation observed in these alloys was explained from the equilibrium diagram of Al-Cu-Mg-Zn, and the expansion and contraction below 100° was considered to be due to the separation of S-compound of Al-Cu-Mg system found by the author, and the contraction continued to about 250° and the subsequent marked expansion were probably due to the separation of MgZn₂.

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When the metals do not make a solid solution all over the range of compositions, the nature of diffusion is very much complex. The following phenomena observed seem, therefore, to be somewhat noticeable.
1) Diffusion phenomena between pure Cu and Zn: The foils composed of many layers of the two metals were made by alternate electroplating. The change of the electric resistance caused by heating these specimens in a vacuum furnace presented a maximum and minimum values at a certain point (Fig. 1, 2 and 3), which was understood as follows; at the beginning of diffusion, there were produced α and β-phases together, and then developed β-phase only, after that β-phase changed gradually to α-phase, and finally becomes chiefly α-phase. The processes were ascertained by the X-ray photographs taken by the back reflection method (Fig. 4).
2) Evaporation of Zn from Zn-Cu alloys: A piece of alloys was heated in vacuum at a certain temperature, and the change of its weight was measured as a function of time. The fact denoted by Dunn that the amount of Zn evaporated varies as the square root of the time, is recognised during a comparatively short time. The X-ray examination of the surface showed that the β-phase loses at first Zn, then α-phase and finally the surface becomes a pure Cu layer as seen in Fig. 6.
3) Diffusion phenomena between Cu and Zn-Cu alloys: A thin Cu plate was pressed against the surface of a block of Zn-Cu alloy, and heated at various temperatures. The each surface of contact was examined with X-ray method; for the Cu surface, there was produced the α-phase which increased step by step (Fig. 8 A), and for the alloy surface there appeared unexpectedly β-phase which vanishes gradually and changed into entirely of α-phase (Fig. 8 B).

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