In an attempt to investigate the acid-resistivity of iron alloys containing a trace of carbon, a series of corrosion tests were conducted by the dip method with specimens of binary iron alloys. As an alloying element Ni, Co, Cu, Mn, V, Cr, Mo, W, Si, and Al were selected, and the specimens were prepared by rolling and annealing from the ingot. The corrosion was examined in 10% HNO₃, 10% HCI and 10% H₂SO₄ aqueous solutions at 25°C by measuring the loss in weight, and the extent of the corrosion was expressed as mg/cm²/hour. The results were discussed by referring equilibrium diagrams. The effect of heat treatments for some alloys on the corrosion was also studied.

抄録全体を表示

With a newly devised dilatometer for low temperatures down to the boiling point of liquid hydrogen, the thermal expansion and its characters of nickel-copper alloys were investigated.
The results of measurements for copper were explained very satisfactorily on the basis of Griineisen's theory, but the anomaly found by F. Simon and R, Bergmann was not observed. The results for nickel will be discussed in a later paper.

抄録全体を表示

The constitution of copperantimony alloys containing up to 18% of antimony has been very precisely established by differential dilatometric measurement and microscopic examination.
The alloys were cast in metal moulds 6mm in internal diameter, and the experiments were made with only those specimens which contain oxides microscopically almost nil. In order to preclude change in composition due to loss of antimony by volatilization, annealing of specimens and dilatometric measurements were made in purified nitrogen.
It is shown that in the course of cooling under equilibrium condition β, η and δ phases separate from α solid solution. The peritectoid reaction (488°) of α and β phases to form η phase accompanies a remarkably large volume change, while the eutectoid reaction (400°) of η phase to decompose into α and δ phases, which does not occur at a constant temperature unless heating and cooling are done extremely slowly, manifests a very small change of volume, and the less the quantity of η phase, the more difficult the deccmposition.
The diffusion and precipitation of δ and η phases into and out from α phase proceed remarkably slowly, especially with δ phase.
The solubility of antimony in α phase is shown to decresae gradually from 10.4% at 645° to 7.6% at 488°, to 6.2%, at 400° and to 4.7%, at room temperature.

抄録全体を表示

In the course of separation of a solute metal and an intermetallic compound or a solid solution, from a supersaturated solid solution, a sudden change is observed more or less in its thermal dilatation curve, but the sense and the amount of the change of length or volume is not determined by the crystal parameters of the original solid solution and the phase separated out, nor by their specific volumes. It is very desirable that some general laws would govern the volume change in the process of precipitation and coagulation of new crystals in a solid solution. In an attempt to find this general law, the writer examined carefully the atomic rearrangementt at the instant of separation and the corresponding change in lattice volume in the transformation.
It is asserted that in the separation of new crystals from a solid solution, there are two types of rearrangement of atoms at the moment of separation: The crystal systems of both phases, solute and solvent metals, are either the same or different, Although the mechanism of transformations of space-lattices is applicable to the latter case, we have to assume a certain other mechanism peculiar to “separation” in the former case. The general low may be stated as follows:
If V₁ is the volume change due to separation of new crystals from a solid solution, and V₂ and V₃ are respectively the volume changes due to the change in crystal parameters of the two phases after the separation has taken place, then the sense and the amount of the reslultant volume change is determined by the algebraic sum of V₁, V₂ and V₃.
Some numerical calculations were carried out for several kinds of ageing alloys whose crystal parameters were well known. Finally the writer briefly discussed the following subjects of the separation of supersaturated solid solutions:
a) The irregularity of thermal dilation curves of solid solutions supersaturated with intermetallic compounds or solid solutions.
b) Some supplementary discussions about the mechanism of age-hardening of Cu-Be alloys.
c) The crystal grain refinement of ageing alloys.
d) The volume change of a carbon steel in quenching and tempering.-Some notes on quenching cracks in steel.
e) Re-examination of the general theory of age-hardening.
f) Deformation of castings.-Especially of Electron and Aluminium alloy castings.
g) Causes of the troubles occurring in modern high powered aeroengines parts exposed to high temperature service.-Heat treatments to be recommended.
h) General considerations on the study of new heat-resisting alloys.

抄録全体を表示

The effect of annealing upon the compositions of dendrites of tin bronze was studied by X-ray back reflection method and microscopic analysis. X-ray patterns have shown broad lines and bands, the former corresponding to the boughs and twigs of the dendrites and the latter to the fillings. The composition of the inner boughs, which were determined from the lattice constans, is richer in tin than those of the outer ones but in the fillings above relations are reversed; i.e, for an alloy having 9.1 % Sn the inner boughs corresponds to 5.3_??_7.0% Sn and the outer to 4.6_??_6.1% and the fillings to 7.0_??_13.3% and 6.1_??_11.9% respectively, and the outer parts contain more δ or η. The tin-rich parts of the fillings are consumed by peritectic reactions, and hence, the outer parts have no tin rich solid solutions. When these alloys are annealed, tin-rich parts of the fillings gradually disappear, and at 700° the alloys will have almost a homogeneous structure.
In α-brass, as the temperature difference between the solidus and the liquidus is not very large and the atomic diameter of Zn is not also much larger than that of Cu, the band corresponding to the fillings of the dendrites becomes narrow, and hence the lines and the bands combine into broad lines. The composition of alloys having 17.2% and 26.6% Zn has shown ranges of 13.8_??_23.9% and 21.8_??_31.8 % Zn respectively, and the latter contained β-phase of 32% Zn which is formed by a peritectic reaction.

抄録全体を表示

The volume changes of the Pb-Cd and Sn-Bi systems during solidification were calculated by applying the mixture rule. In this calculation, the specific volumes of component metals at liquidus and solidus points were adopted, the values of which were calculated by the expansion coefficient of component metals.
The calculated results of the above two alloy systems agree well with the experimental results by the author in the First Report therefore, the author gave a satisfactory explanation of the experimental results in the First Report.

抄録全体を表示