Ag-CdO-NiO alloys having various Cd contents were prepared by internal oxidation in the temperature range from 700° to 800°C. Welding resistance and erosion characteristics of this contact material have been measured in the range of applied voltage from 40 to 100 volts and circuit current from 12 to 43 ampers. The results obtained are as follows:
(1) Welding resistance of Ag-CdO contact in the circuit of alternating current is improved by the addition of 0.3%Ni, because CdO particles in the alloy are homogeneously dispersed. The amount of the alloying element for the maximum of welding resistance is given at 12%Cd in Ag-CdO-NiO alloys, but the minimum of erosion is given at 8%Cd and the amount of erosion is 1/10 that of silver contact.
(2) In the circuit of direct current, the welding resistance of silver alloys is decreased by the degenerate layer depending of the metal migration from anode to cathode of the electrical contact material, and the silver contact shows the maximum welding resistance.

抄録全体を表示

The effect of carbon, silicon and manganese on the formation of a boride layer and its properties was studied. The used materials were iron alloys containing 0.25∼1% carbon, 0.5∼5% silicon or 0.5∼5% manganese. The experimental results were as follows:
(1) The formation of the boride layer in Fe-C and Fe-Si alloys was impeded as the addition of carbon or silicon was larger, but the addition of manganese had no effect in Fe-Mn alloy.
(2) From the results of X-ray diffraction it was observed that the diffuse-coated layers of all specimens consisted of two layers of FeB and Fe₂B independently of alloying elements.
(3) The carbon and the silicon in Fe-C or Fe-Si alloy was diffused to the center of the specimen with the growth of the boride layer. Consequently, it was found that in hyper eutectoid steel a cementite precipitated and in Fe-Si alloy silicon made a solid solution with iron containing a large quantity of silicon between the boride layer and the matrix.
(4) From the analysis by an electron microprobe X-ray analyzer the existence of manganese was observed in the boride layer of Fe-Mn alloy.

抄録全体を表示

The temperature variation of the electrical resistivity was measured at various concentrations of binary liquid alloys, Zn-Cd, In-Tl, Sn-Pb and Sb-Bi, having the same value in the valency of their solute and solvent metals. The resistivity for these alloys obtained from the above experiments was found to be approximately changed in proportion to the concentration of solute atoms over its whole range for each alloy system.
Distribution of solute and solvent species in these liquids can be assumed to be random because of the mutual interaction being approximately unchanged between like atoms and unlike atoms having the same valency. Under the above assumption a formula for the concentration dependence of resistivity of alloys was deduced, which was composed of two terms. The first term contributes to the main part of the resistivity leading to the linear dependence upon the concentration, and the second term is a cross term depending the square of the difference between scattering potentials of solute and solvent ions, (U_A−U_B)². When the pseudo-potential obtained by Animalu and Heine is used as the scattering potential of each ion, it can be considered that such potentials of ions with the same valency are similar so that the contribution of the second term to the resistivity is small compared with that of the first term. Thus the nearly linear dependence of the resistivity upon the concentration of alloy is obtained.
Small deviations of the concentration depencence from the linearity for respective alloys was discussed from the variation of the pseudo-potential of ions caused by alloying.

抄録全体を表示

Reaction-diffusion in the Ti-Ni system was investigated in the temperature range between 500° and 900°C, using diffusion couples of pure Ti and pure Ni.
Above the eutectoid temperature of the β-Ti solid solution, the greater part of the diffusion zone consisted of β-Ti, while the Ni solid solution scarcely grew in it at the experimental temperatures.
All of the three intermediate phases, TiNi₃, TiNi, Ti₂Ni, existing in the equilibrium phase diagram were observed in the diffusion zone at all the experimental temperatures. The apparent activation energies for the growth of TiNi₃, TiNi, Ti₂Ni phases are 16.1, 27.2 and 11.9 kcal/mol, respectively. It appears that such low activation energies are attributed to the excess vacancies in the intermediate phases of nonstoichiometric compositions.
The composition range of the TiNi phase was determined from the concentration-penetration curves of the diffusion couples, and compared with the results of other workers. The composition range tends to decrease as temperature decreases, and at the Ni-rich side it is in good agreement with that obtained by Hume-Rothery et al. and Parr et al., but at the Ti-rich side it is displaced to the Ti-richer side.

抄録全体を表示

In order to account for the development of {111} texture in a cold rolled mild steel sheet, the relation between crystal orientation and recrystallization behavior has been studied by electron microscope observation and the statistical treatment of the results of selected area diffraction. The results are summarized as follows. (1) In the cold rolled state, the areal fraction of the {111} plane is relatively large compared with that of the {100} plane. (2) In the {111} region, formation of subgrains and recrystallization occur easily, while the {100} region has a tendency to remain as deformed matrix. (3) At the early stage of recrystallization, the number of {111} recrystallized grains is more than that of the recrystallized grains of other orientation. Moreover, these {111} grains seem to recrystallize in situ. (4) The {100} recrystallized grains are smaller in size than the {111} grains, resulting in the increase of the {111} region in the course of grain growth.

抄録全体を表示

Effective distribution coefficients, k, of some solute elements in commercial steels, JIS SCM 3, SUJ 2 and SUS 27, have been determined by a floating zone melting technique. From values of k obtained for various growth rates, equiliblium distribution coefficients, k₀, are calculated by Burton’s equation. But, the values of k obtained at growth rates faster than 4 cm/hr deviate from the equation.
It is found that the values of k₀ of the solute elements in commercial steels (k₀<1) are somewhat larger than in Fe base binary alloys. This is caused by the interaction between solute elements in the steel.
S, P and C yield not only small values of k₀ but also the values of k which strongly depend upon growth rates.

抄録全体を表示

Hydrochloric acid extraction, potentiostatic electrolysis with Na-citrate-KBr electrolyte and potentiostatic electrolysis with HCl-FeCl₃-ethyleneglycol electrolyte were studied for quantitative extraction of vanadium carbide (V₄C₃) from continuously cooled Fe-V-C steel. The highest values and good precision were given by potentiostatic electrolysis with HCl-FeCl₃-ethyleneglycol electrolyte. A recommendable procedure is as follows.
About 0.5 g of the sample is potentiostatically electrolyzed at −280 mV vs SCE in about 400 mL of 7%HCl-3%FeCl₃-ethyleneglycol. The extracted residues are collected through a Cella filter and washed by ethylalcohol. Vanadium in the residues is determined by NBPHA spectrophotometry and calculated as vanadium carbide (V₄C₃).
By this procedure, 0.006∼0.2% vanadium carbide in steel was determined with good reproducibility. The time required for the extraction was about 10 hr and the time for the vanadium determination was about 30 min.

抄録全体を表示

A infrared spectrophotometric method was developed for the rapid identification of trace amounts of boron nitride (BN, down to 0.0001% in steel of boron as BN) in the residues extracted with sulphuric acid from steel samples. From the studies on commercial boron nitride (BN) and the above-mentioned residues which were found to contain boron nitride by element analysis and electron diffraction, boron nitride was newly found to have highly sensitive and characteristic absorption bands at 819 and 1383 cm⁻¹ and to be simply identified by these absorption bands with no interference from compounds usually contained in the residues. A recommendable procedure is as follows.
The residues by the acid extraction from 2∼5 g of the chipped sample is collected through the Millipore filter (100 mμ) and dried at room temperature. The residue is transferred into 300 mg of potassium bromide powder with Johnson’s method and ground well in agate mortar with potassium bromide for about 20 min. Infrared absorption spectrum is measured over the frequency range between 600 and 1600 cm⁻¹, using disk-like pressed powder (diameter: 13 mm, thickness: 1 mm). Boron nitride is identified by the characteristic absorption bands at 819 and 1383 cm⁻¹.
This method may be developed for a quantitative analysis of trace amounts of boron nitride in the residues extracted from steels.

抄録全体を表示

Wear of cast iron in air and vacuum under the unlubicated condition and the frictional hardened layer formed at a high sliding speed were examined. Results obtained were summarized as follows:
(1) In air, oxidative wear, in which the sliding surface and wear debris are oxidized, is observed at lower and higher speeds than about 1.5 m/s at which mechanical wear occurs. Wear at a high sliding speed can be attributed to oxidation and local melting of the sliding surface.
(2) In vacuum, mechanical wear occurs up to about 2 m/s, because of the absense of oxidation. However, wear loss decreases as the sliding speed increases.
(3) The frictional hardened layers, of which maximum micro-hardness is over Hv 1000, are formed on the sliding surface at high sliding speeds.
(4) X-ray analysis has confirmed that the hardened layer is composed of ferrite, austenite, martensite and free cementite. This may contain an extremely fine ledeburite structure deformed severely.
(5) It is certain that some real contact regions of the sliding surface are partially melted at a high sliding speed. Therefore, it is supposed that the formation of the frictional hardened layer is due to the rapid solidification and cooling of the melting regions and also due to severe deformation.

抄録全体を表示

The method for determination of boron and cadmium in zircaloy-2 by the D.C. arc spectrographic technique was developed. The metal sample was converted into the oxide, 100 mg of which in graphite electrode was excited by D.C. arc at 14A. Exposure condition, preburn: 3 sec, exposure time: 22 sec for boron and 10 sec for cadmium, was extremely critical in this method. Two spectra, differing in the exposure condition, were obtained at one discharge of one sample electrode with a special diaphram in front of the entrance slit of the 3.4-meter Ebert mounting spectrograph. Precision of the method was 20∼25% in coefficient of variation, with satsifactory results in routine analysis.

抄録全体を表示

Zur Untersuchung über die Zunahme oder Abnahme des Drahtdurchmessers bei der Hin-und Herbiegeverarbeitung des Stahldrahtes wurden die verschiedenen Stahldrähte unter verschiedenen Biegebedingungen verarbeitet und dann wurden die Durchmesser dieser Stahldrähten gemessen. Folglich wurde Einfluss jedes Faktoren anf der Änderung des Drahtdurchmessers aufklären.
Die Versuchsergebnisse zeigen, dass der Durchmesser des patentierten Stahldrahtes bei Biegeverarbeitung nicht zunimmt und nur bei schweren Biegeverarbeitung wie mit kleinem Biegedurchmesser, grossem Umschlingungswinkel und grosser Biegezahl abnimmt. Dagegen nimmt der durchmesser des gezogenen Stahldrahtes bei leichter Biegeverarbeitung zu und bei starker Biegeverarbeitung ab. Die Zunahme des Drahtdurchmessers bei Biegeverarbeitung des gezogenen Stahldrahtes ist an der grösst beim Verhältnis von Biegedurchmesser zu Drahtdurchmesser von rund 20. Die Abnahme des Drahtdurchmessers wird in sowohl patentiertem als auch gezogenem Draht mit stark werdender Biegeverarbeitung grösser. Ferner wird diese Abnahme mit abnehmendem Kohlenstoffgehalt grösser und bei Gesamt-Querschnittsabnahme von 0 oder etwa 80% gross.

抄録全体を表示

It has already been recognized by many researchers that lead oxides, combustion products of tetraethyl lead, cause high temperature catastrophic corrosion of engine exhaust valves and ignition plugs. But their studies relate for the most part to the reactions in the molten state of PbO.
Our experiments were performed to investigate how heating atmosphere, especially oxygen partial pressure, influences the high temperature corrosion of Ni by PbO in the temperature range 500°∼800°C i.e. below the melting point of PbO.
The results of experiments were summarized as follows:
(1) When Ni was heated with PbO powder under atmospheric pressure, a dense and homogeneous oxide layer was formed in a manner similar to the oxidation in air, and in this case PbO showed a tendency of slightly accelerating the oxidation. But in case oxygen pressure in heating atmosphere was reduced, quite different corrosion phenomena were observed; namely Ni was aggressively corroded by PbO forming voluminous corrosion products.
(2) In our experiments of 2 hr heating, this aggressive corrosion was observed to start at 650°C and to be especially prominent over 750°C.
(3) The X-ray diffraction data confirmed that the main components of the corrosion products were NiO and Pb.

抄録全体を表示

In our previous paper it was reported that Ni was aggressively corroded by PbO at the reduced oxygen pressure in heating atmosphere.
This report describes the process of the aggressive corrosion observed by using an optical microscope, an X-ray spectroscope and an electron probe micro analyser. To determine the accelerating factor of the corrosion rate, Fe, Cr, and other metals were also examined on their corrosion behaviour.
The results obtained are as follows.
(1) Catastrophic corrosion caused by PbO in reduced oxygen atmosphere is a characteristic phenomenon for the metals of Ni and Fe, and is not observed for other metals.
(2) Melting reaction between NiO and PbO is not observed at the test temperature of 800°C.
(3) The probable process of the catastrophic corrosion may probably be assumed as follows.
Due to some catalytic actions Ni accelerates the decomposition of PbO. Thin layer or grains of Pb deposited on the surface of Ni causes the dissolution of Ni into molten Pb as well as grain boundary corrosion of Ni. The Ni dissolved in molten Pb is subject to preferential oxidation on the surface of the melt and forms a larger amount of NiO.

抄録全体を表示

Microstructural changes UN fuel elements including the vibratory compact of arc-fused UN, the sintered pellets containing a high UO₂ impurity and the vibratory compact of the powder prepared by crushing the sintered pellets were investigated under the influence of a steep temperature gradient by center-line heating technique at high temperatures in a vacuum of 1.0×10⁻⁴ mmHg.
Main results obtained were as follows:
(1) In the central regions of UN fuels, where the temperature was above 1800°C, uranium metal was precipitated by the decomposition of UN.
(2) Columnar grain growth, which was usually observed in UO₂ fuel heated under a temperature gradient in vacuum, was not found to occur.
(3) There was no appreciable difference in the microstructural changes between the vibratory compact of arc-fused UN containing a low UO₂ impurity and the vibratory compact of the powder prepared by crushing sintered pellets containing a high UO₂ impurity.
In addition, the microstructure at the interface of UN-UO₂ contact pellets after center-line heating was investigated.

抄録全体を表示

The effect of solute elements on the primary aluminum dendritic structure in columnar crystals have been investigated with various aluminum-base hypo-eutectic binary alloys whose equilibrium distribution coefficients are smaller than unity.
The dendrite element size Z can be expressed as Z=α\sqrtC₀⁄V_s, where C₀ is solute content and V_s is the cooling rate in the solid-liquid coexisting region. The value of α is larger at low solute content and decreases more rapidly with increasing solute content for an alloy system whose equilibrium distribution coefficient is less. The relation that the dendrite element size is larger for an alloy system whose distribution coefficient is less has been reported previously, but the relation is not satisfied at high solute content.
The dendrite arm spacing is inversely proportional to the fourth root of the cooling rate at the solid-liquid coexisting region, and decreases with increasing solute content. The spacing is smaller for the alloy system whose equilibrium distribution coefficient is less.
These phenomena are explained by the concentration of solute at the solid-liquid interface during solidification.

抄録全体を表示

In order to estimate metallic iron and ferrous oxide in reduced iron ores, brominemethyl alcoholic solution has been extensively studied in regard to its stability and dissolution behavior for metallic iron and iron oxide.
The experiments proved that bromine-methyl alcoholic solution is rather unstable and an acidic substance yields slowly on standing. By chemical and X-ray diffraction tests, it was found that metallic iron is completely attacked but iron oxides are not by means of bromine-methyl alcoholic solution containing an acidic substance. Bromine-methyl alcoholic solution is best prepared by adding bromine to methyl alcohol which contains formic acid (10%) and shaking for a while just before use.
Satisfactory results were obtained by applying the proposed method to the analysis of reduced iron ore samples.

抄録全体を表示

The strain gauge factor K at room temperature, the electrical resistivity ρ at 20°C and its mean temperature coefficient C_f, and the mean thermal electromotive force E_mf in the temperature range of 0° to 40°C have been measured with wires of Fe-Cr alloys containing 0∼50% chromium in a cold-worked state of about 98% reduction. It has been found that the largest value of K obtained is 6.2 for the Fe-Cr alloy containing 20% chromium, ρ, C_f and E_mf of which are 44.6 μΩ-cm, 32.7×10⁻⁴ and 11.0 μV/°C, respectively.

抄録全体を表示

A modified isothermal phase diagram of the Nb-Zr-Ti ternary system at 570°C is presented. In this new phase diagram, a new α_Zr+β′+β″ phase region is added and the diagram at 570°C conssists in the following eight phase regions; α_Zr, α_Zr+β′, α_Zr+β″, α_Zr+β′+β″, β′+β″, β, α_Ti+β and α_Ti.

抄録全体を表示

In the present paper, the tensile properties of copper between room temperature and 550°C are described as a function of the strain rate ranging from 2.7×10⁻³ to 1.6×10² l/sec.
Results obtained are summarized as follows:
(1) Although a remarkable drop in ductility was observed around the temperature of 350°C under slow deformation, it disappeared gradually with increasing strain rate. Especially, the decrease in ductility was never found beyond the strain rate of 1.7 l/sec.
(2) The temperature range in which the brittleness occurred did not shift to higher temperatures and the specimen behaved in the most brittle manner at about 350°C for all strain rates. This fact suggests that the brittleness is not attributed to any diffusion process.
(3) At a given strain rate, the tensile strength did not show any abnormal variation corresponding to the brittleness at 350°C, i.e., it decreased almost linearly with temperature.
(4) The tensile strength was expressed well by an increasing linear function against the logarithm of the rate at a given temperature, and there was only one strain rate sensitivity for the strength through the strain rate encountered in the present experiment. The sensitivity increassed with temperature but it was much smaller than that for the tensile strength of steel.
(5) The deformation resistance at room temperature at a small strain, 2.65%, had the same strain rate sensitivity as that for the tensile strength at the same temperature. This result allows the deduction in which the strain hardening exponent of copper does not change with the strain rate.

抄録全体を表示

A simple, rapid, and accurate method is described for the determination of iron, nickel, and copper in samples which contain some refractory matals. Samples are dissolved in a nitric and hydrofluoric acid mixture, and saturated boric acid solution is added to the solution to mask the excess of hydrofluoric acid. Iron, nickel, and copper are determined directly in the final sample solution by X-ray fluorescence analysis. The effect of the element of interest was negligible below 2 normal. The interelement effects of iron, nickel, and copper, however, were considerably large, so that a correction had to be considered for the diverse element. This proposed method is so rapid that it took only about 10 minutes for the analysis of one sample. The relative errors of analytical results were below 3 per cent. This method, moreover, may have a broad applicability in the analysis of refractory metals in alloy steels and other alloys.

抄録全体を表示