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Volume 42, Issue 8
Displaying 1-12 of 12 articles from this issue
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Yoshisada Ueda, Seizi Kunimitsu1978 Volume 42 Issue 8 Pages 751-756
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPb-Al2O3 composites, containing 2, 4, 6 and 8 vol%Al2O3 1 μm in particle size, were made by a mechanical alloying process and the hot hardness was measured in the temperature range from 293 to 513 K by a hot micro-Vickers hardness tester.
The hot hardness of Pb-Al2O3 composites is higher than that of pure Pb at all temperatures investigated. With increasing Al2O3 volume fraction and temperature, the hot hardness is proportional to the reciprocal of the interparticle distance and of the exponential of the absolute temperature, respectively.
The creep behavior of Pb and Pb-Al2O3 composites in compression may be also estimated by the loading time dependence of hardness with constant load, and the creep rate (\dotε) can be expressed as follows.
(This article is not displayable. Please see full text pdf.)
\ oindentwhere σ is a mean stress on the contact area of the indenter, and K1 and K2 constants of material.View full abstractDownload PDF (564K) -
Hiroshi Nagai, Teruyuki Murai, Hiroyasu Mitani1978 Volume 42 Issue 8 Pages 756-763
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe isothermal oxidation behavior of Fe-20 Cr alloys with additions of 0, 0.2, 0.5, 0.7, 1.0 and 1.3 wt%La was studied in air at 1273 K by weight gain measurements, scanning electron microscopy, X-ray diffraction and electron probe microanalysis.
The alloys with additions of 0.2%La or less exhibited severe oxidation with the formation of thick stratified scales of α-Fe2O3 and spinel oxide. On the other hand, the alloys with additions of 0.5%La or more exhibited good oxidation resistance. The formation of the protective La2O3 or LaCrO3 layer at the scale base, the convoluted alloy/oxide interface and the enhanced diffusion of any particular element were not observed in this study, although these had been proposed to be main mechanisms by which the improvement of oxidation resistance was enhanced by the rare earth additions. Since additions of 0.5%La or more completely suppressed the formation of the iron oxides and the Cr2O3 scale was maintained stably during the oxidation period, the oxidation behavior of Fe-20 Cr binary alloy and the affect of La addition were discussed thermochemically.View full abstractDownload PDF (1421K) -
Shinya Komatsu, Takayoshi Hata, Takashi Sugimoto, Katsuya Akamatsu, Ki ...1978 Volume 42 Issue 8 Pages 763-769
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe change in electrical resistivity of age-hardening aluminium alloys deformed at 78 K was carefully measured by the method of tracing the size factor change after deformation using file-finished specimens. A resistivity minimum with tensile strain was observed in Al-2.64 at%Zn-1.40 at%Mg and Al-4.5 at%Zn alloys aged at room temperature, while such a decrease was not seen in Al-1.7 at%Cu alloy. The initial rate of resistivity change by aging after low temperature deformation was increased with increasing amount of tensile strain. The resistivity minimum was explained by the resistivity decrease due to the reduction in size of the spherical G.P.zone cut by dislocations and the resistivity increase due to the multiplication of lattice defects by deformation.
The ratio of the zone number cut by dislocations was roughly estimated to be more than 30% when the Al-4.5 at%Zn alloy was deformed upto 10%.View full abstractDownload PDF (938K) -
Yoshiyuki Saita, Mitsunori Tsutsui1978 Volume 42 Issue 8 Pages 769-775
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to determine different types of carbides existing in annealed high speed steels, metallographic specimens were oxidized potentiostatically at various anodic potentials in a 1M sodium hydroxide solution and examined by electron microprobe analysis. The anodic oxidation behavior of carbides was discussed on the basis of the anodic polarization curves measured in the same solution. In addition, the volume fraction of M6C was estimated as a function of quenching temperature by measuring the electric charge during anodic oxidation and by comparing the results obtained by point counting. The following conclusions are drawn from the results:
(1) The carbide particles stained brown to blue at 0 V vs SCE are identified to be M6C.
(2) In the anodic polarization curves three current peaks are observed. These peaks are attributable to the dissolution of tungsten, molybdenum and vanadium in the matrix, M6C and M23C6, respectively.
(3) The volume fraction of M6C determined from the amount of electric charge is nearly equal to the value obtained by point counting.View full abstractDownload PDF (746K) -
Takahiro Kou, Kazuichi Mizoguchi, Yukio Suginohara1978 Volume 42 Issue 8 Pages 775-781
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe results of viscosity measuerments for Na2O-SiO2-Al2O3 and PbO-SiO2-Al2O3 systems and the previous data for CaO-SiO2-Al2O3 and MnO-SiO2-Al2O3 systems have been used to evalute the effect of Al2O3 on the viscosity of the ternary aluminosilicate MO-SiO2-Al2O3 system in the range of molar ratio Al2O3/MO<1. The results obtained are summarized as follows:
(1) In the Na2O-SiO2-Al2O3 system, the viscosity greatly increased with the substitution of Al2O3 for SiO2 and the value of SiO2-equivalence of Al2O3 calculated from the resutls was about 1.65. In this system, it was considered that Al-ion forms oxygen tetrahedron likewise Si-ion and acts as the aluminosilicate anion.
(2) In the PbO-SiO2-Al2O3 System, the viscosity slightly increased and the rate of increase decreased with decreasing basicity of melts.
(3) In the CaO-SiO2-Al2O3 and MnO-SiO2-Al2O3 systems, the viscosity decreased in the range of molar ratio MO/SiO2<1 with increasing concentration of Al2O3 and the rate of decrease became larger with decreasing basicity of melts. Therefore accurate assessment of the results of these systems could not be made simply by the values of SiO2-equivalence of Al2O3.
(4) Satisfactory results were obtained by arranging the viscosity data by each alminosilicate using a parameter (nSi+xnAl)⁄nO, the value which corresponds to nSi⁄nO in the binary silicates, where nSi, nAl and nO are the ion fraction and x is a constant. The calcurated values of x were 0.90(Na2O), 0.74(PbO), 0.69(CaO) and 0.64(MnO), and the relation between their values and ion-oxygen attraction of each oxide was linear.View full abstractDownload PDF (545K) -
Yoshikiyo Ogino, Mitsuaki Shibata, Yoshitsugu Amano1978 Volume 42 Issue 8 Pages 782-786
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of boron on the embrittlement of cathodically hydrogen-charged nickel was studied by comparing tensile properties and the cracking behavior on room temperature aging. By adding small amounts of boron in nickel, the loss of ductility due to the hydrogen significantly decreased, the intergranular cracking being suppressed. Such an effect of boron on hydrogen embrittlement of nickel may be due to equilibrium segregation of boron in grain boundaries.View full abstractDownload PDF (818K) -
Akihisa Inoue, Tsuyoshi Masumoto1978 Volume 42 Issue 8 Pages 787-795
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe carbide reactions of M3C→M7C3→M23C6 were examined by electron microscopy using two kinds of high carbon-high chromium steels quenched rapidly from the melts. In tempered 16.5%Cr-3.65%C steel, M7C3 carbide was observed to nucleate on the cementite/ferrite interface and grow at the expense of cementite. This indicates that the transformation from cementite to M7C3 occurs by the in situ mechanism. The in situ transformation from M7C3 to M23C6 was also observed in tempered 45.4%Cr-2.15%C steels. Lattice relationships among M3C, M7C3 and M23C6 were determined as follows:
\ oindent(0\bar11)M3C\varparallel(0001)M7C3, (012)M3C\varparallel(1\bar100)M7C3, (\bar100)M3C\varparallel(11\bar20)M7C3, and (0001)M7C3\varparallel(\bar12\bar1)M23C6, (1\bar100)M7C3\varparallel(111)M23C6, (11\bar20)M7C3\varparallel(10\bar1)M23C6.View full abstractDownload PDF (988K) -
Yasunori Torisaka, Junji Kihara1978 Volume 42 Issue 8 Pages 796-800
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe strain tempering for a heating time of 0.2 s was performed on the cold-drawn wires of pure nickel, OFHC copper and 65∼35 brass, all with FCC crystal structure.
The effect of the heat treatment on the improvement of resistance to stress relaxation for nickel wire was nearly equal to a low carbon martensite rod and PC steel wire. On the other hand, the effects for OFHC wire and 65–35 brass wire were negligibly small at least on the improvement of the resistance to stress relaxation at ambient temperature.
These results are discussed in comparison with the published data on low carbon martensite rods, PC steel wires and decarburized iron wire, and the depressing effect of the strain tempering on the stress relaxation is proposed to be due to a three-dimensional rearrangement of cold-worked substructures.View full abstractDownload PDF (361K) -
Hideki Hagi, Yasunori Hayashi, Namio Ohtani1978 Volume 42 Issue 8 Pages 801-807
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe electrochemical permeation method is widely used for the measurement of the diffusion coefficient of hydrogen in the vicinity of room temperature. The method, however, is not applicable to the temperatures below the freezing point of aqueous solution used as the electrolyte. At temperatures lower than 273 K, therefore, only a few measurements have been carried out by means of internal friction and magnetic disaccomodation. In the present work, hydrogen permeation through single and poly-crystalline specimens of fully annealed iron was measured at temperatures between 230 and 300 K by an improved electrochemical method in which alcoholic solutions were used as electrolytes. The obtained hydrogen permeation curves were analyzed taking special consideration for the variation of the hydrogen concentration at the cathode surface during the measurement. The diffusion coefficient of hydrogen thus obtained in single crystalline iron is given by 1.1×10−7exp(−6700(J/mol)⁄RT), but in the polycrystalline specimens it is not expressed by a single Arrhenius equation. The diffusion coefficient at 298 K is 7×10−9 m2/s, and is independent of the existence of grain boundaries, cathodic current density and the thickness of the specimen.View full abstractDownload PDF (561K) -
Shiro Matsuda, Ko-ichi Hamano, Katsuhisa Sugimoto, Yoshinobu Sawada1978 Volume 42 Issue 8 Pages 808-814
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe passive films on 17 Cr-13 Ni steels containing 0∼3 wt%Mo and 20 Cr-25 Ni steels containing 0∼5 wt%Mo in 0.5 mol/l H2SO4 and in 1.0 mol/l-HCl have been measured by ellipsometry under potentiostatic control.
Optical constants for the film-free surfaces of these steels were ellipsometrically determined in dehydrated methanol immediately after the film removal treatment in 0.5% bromine-methanol solution. The values were used for the analysis of ellipsometric data obtained for passive films on the steels. It was found that the optical constants of the passive films formed in 0.5 mol/l-H2SO4 were virtually independent of the Mo content of the steels; N2=2.3−0.3i for 17 Cr-13 Ni steels containing 0∼3 wt%Mo, N2=2.3−0.2i for 20 Cr-25 Ni steels containing 0∼5 wt%Mo. The film thickness and its growth rate with potential were both increased with incresing Mo content.
The optical constant of the passive film on 20 Cr-25 Ni-5 Mo steel in 1.0 mol/l-HCl was 2.0−0.2i. The film thickness and its growth rate with potential were smaller than those for the passive film formed in 0.5 mol/l-H2SO4. The difference in optical properties between the film formed in 0.5 mol/l-H2SO4 and that in 1.0 mol/l-HCl may be attributed to different chemical compositions of the films.View full abstractDownload PDF (580K) -
Muneo Oka, Yoshiyuki Taniguchi1978 Volume 42 Issue 8 Pages 814-820
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe stress-induced products formed by cold-rolling in Ti-11∼20%Mo and Ti-16%V binary alloys have been examined by means of optical microscopy, X-ray diffraction and transmission electron microscopy.
Plate-like products in a Ti-11%Mo alloy with a meta-stable β phase were {332} twins and a small amount of orthorhombic martensites, and those in Ti-13%Mo, 15%Mo and 16%V alloys with a meta-stable β phase were {332} twins. Meanwhile, plate-like products in a Ti-20%Mo alloy with a stable β phase were {112} deformation twins. It is considered that the unusual {332} twinning in bcc crystals is associated with the unstability of atoms in a meta-stable β phase rather than with the presence of the ω phase formed during quenching.View full abstractDownload PDF (851K) -
Kingo Nagaoka, T\={o}ru Noguchi, Makoto S\={o}ma, Kanou Suzuki1978 Volume 42 Issue 8 Pages 821-822
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (153K)
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