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Volume 45, Issue 5
Displaying 1-15 of 15 articles from this issue
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Kazuhiko Kuribayashi, Teruo Kishi, Ryo Horiuchi1981 Volume 45 Issue 5 Pages 449-456
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of deformation twinning on AE in zinc single and polycrystals was evaluated quantitatively. AE observed at the stage II deformation of zinc single crystal consists of a mixture between continuous type emission and burst type emission. The former corresponds to the basal slip, and the latter to the deformation twinning. The fraction of deformation twinning to the total amount of the plastic deformation was estimated to be 0.3 on the basis of the analysis of the distribution of AE amplitudes. The AE behavior during the tensile test of zinc polycrystals could be well explained by the kinetics with respect to the multiplication and the annihilation of dislocations. Particulary the strain rate dependence of AE activity in zinc polycrystal could be well explained by the present kinematical analysis.View full abstractDownload PDF (628K) -
Hisashi Kuwano, Yasuhiro Morooka1981 Volume 45 Issue 5 Pages 457-463
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo obtain the fundamental knowledge about the lattice vibration and the magnetic property of the Cr-rich phase precipitated in various Fe-Cr alloys aged at 748 K, the internal field, the isomer shift and the second-order Doppler shift of 57Fe in the phase have been measured by means of Mössbauer spectroscopy. Results are summarized as follows:
\ oindent(1) The isomer shift of 57Fe in the Cr-rich phase is −0.124±0.001 mm/s at room temperature. Substitution of the value into the empirical equation between the isomer shift IS and the chromium concentration x: IS=−0.00145x, found earlier by the present auhtors, gives a value of 86±1 at%Cr for the chromium concentration of the phase. (2) The temperature dependence of the second-order Doppler shift gives a Debye temperature of 445±15 K for the 57Fe solute in Cr-rich phases, which is approximately 50 K higher than in an Fe-86.7 at%Cr alloy quenched from 1273 K. (3) The Cr-rich phase has a Néel temperature of 200 K which is abnormally higher than that of the Fe-86.7 at%Cr alloy. It is believed that the magnetic structure of the former changes in the order of paramagnetic→spin density wave→purely antiferromagnetic state with lowering temperature, in a similar way to that of the latter.View full abstractDownload PDF (570K) -
Katsutoshi Ono, Yukitomi Ueda, Joichiro Moriyama1981 Volume 45 Issue 5 Pages 463-470
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIsothermal degassing of the Nb-C-O solid solutions under vacuum and low CO-pressures has been studied by measuring the carbon and oxygen contents as a function of degassing time at 2073∼2473 K. Carbon is removed by degassing as CO and oxygen is eliminated as CO and volatile suboxides such as NbO and NbO2.
The observed degassing curves were compared with the theoretical laws which had been deduced from the kinetic analysis of certain elementary steps of the degassing process. In the case of low carbon contents, the diffusion via interstitials was supposed to be rate-determining for the complete process. For relatively higher oxygen contents, the rate-determining step for elimination of oxygen was supposed to be a combination of oxygen in the adsorbed state and carbon or niobium atoms to form molecules and leave the surface.
At low CO-pressures, the degassing was well expressed by straight lines indicating that the most part of the adsorption sites on the surface are occupied by the gaseous molecules.View full abstractDownload PDF (528K) -
Yoshinori Nishida, Hiromi Matsubara, Itaru Shirayanagi1981 Volume 45 Issue 5 Pages 471-474
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe pressure dependence of the temperature rise of molten Al and Zn by rapid adiabatic compression was measured. The temperature rise of molten Al agreed comparatively well with that calculated by classical thermodynamics using its physical properties at normal pressure. But the temperature rise of molten Zn was much larger than that calculated in the same way. The values of (∂V⁄∂T)p of these metals at high pressure were determined by experimental results obtained. The value of (∂V⁄∂T)p of Al gradually decreases with increasing pressure, while that of Zn increases with pressure in the pressure range 0∼200 MPa.View full abstractDownload PDF (310K) -
Koichi Arai, Satoshi Sunada, Toshiyuki Nakamura, Toshio Izaki1981 Volume 45 Issue 5 Pages 474-480
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe oxidative leaching reaction of nickel sulfides in nitric acid solutions were examined from both thermodynamic and kinetic points of view, by carrying out the determination of leaching rates, the measurement of rest potentials and so on.
The main results obtained are as follows:
(1) The oxidative leaching rates of nickel sulfides in nitric acid solutions were influenced greatly by the stoichiometry of nickel sulfides. Reaction with stoichiometric nickel sulfide proceeds faster than that with nickel-deficient ones. This tendency is explained thermodynamically by the decrease in driving force of leaching reaction.
(2) The rest potential of non-stoichiometric sulfide was influenced by the concentration of nickel ion, hydrogen ion and the composition of sulfide ores. However, the concentration of nickel ions does not affect the rest potential of stoichiometric nickel sulfide.
(3) The oxidative leaching reaction of nickel sulfides is a simultaneous reaction of elemental sulfur formation and sulfate ion formation.
(4) The overall reaction of the oxidative leaching of nickel sulfides in nitric acid solutions is controlled by a chemical reaction step and the rate equation is given by the following equation.
(This article is not displayable. Please see full text pdf.)View full abstractDownload PDF (542K) -
Keikichi Nakamura, Takehiro Dan1981 Volume 45 Issue 5 Pages 480-487
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWhen metal absorbed hydrogen, the lattice spacing increases in proportion to the amount of hydrogen absorbed. However, if the metal surface is clean and the bulk diffusion is the rate-determining step, generation of stress, similar to thermal stress, arises due to the existence of hydrogen concentration gradient. If the equivalent stress exceeds the yield stress for uniaxial tension of the solvent metal (Mises criterion), the dilatation of which is no longer a linear function of the solute concentration. In the present study, elastoplastic strain of Pd coated Nb and Ta cylinders during hydrogen absorption was analysed by means of successive approximations by Manson. The results were applied to the determination of hydrogen absorption rate by use of a dilatometer.
The following conclusions were obtained.
(1) The magnitude of triaxial stresses generated in the cylindrical specimen is the function of L which expresses the degree of contribution of the surface process. If the reaction is surface-controlled (L<<1), the generated stress is so small as to produce any problems relevant to hydrogen absorption.
(2) If Pd is coated on Nb and Ta cylinders, the reaction becomes diffusion-controlled (L>>1) and the generated equivalent stress, the extent of which depends on hydrogen pressure and temperature, exceeds the yield stress.
(3) Because of the elastoplastic strain generated in Pd coated Nb and Ta cylinders, the observed dilatation is smaller than that calculated by assuming pure elastic strain. The calculated elastoplastic strain for Pd coated Nb cylinder shows that the deviation from pure elastic strain amounts to 50% under the conditions L=13.5, ce=0.22 and T=723 K.
(4) The observed dilatation curves due to hydrogen absorption for Pd coated Nb and Ta cylinders were treated taking into account of the correction method cited in (3) and the rate constants were obtained. The results agree well with the established hydrogen diffusion coefficient from Gorsky effect (Schaumann et al.) and confirm the absorption model used in the present investigation.View full abstractDownload PDF (646K) -
Masako Nakahashi, Shinichi Nakamura, Shuichi Komatsu, Hiroshi Yoshida1981 Volume 45 Issue 5 Pages 488-496
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA detailed examination was made on the carbide in tempered 12Cr-Mo-V-W steel in use for steam turbine blades.
Quantitative analysis was carried out on individual carbides extracted from the steel by a scanning electron microscope with an X-ray energy spectrometer. Particular precaution was taken to induce radiation from the matrix using a carbon extraction replica and a specially desighned sample holder.
It was observed that the chromium content concentrated in both needle like M3C carbide and fine M7C3 carbide as the tempering temperature increased. On the other hand, M23C6 carbide composition is almost constant during high temperature tempering.
The M3C-M7C3 transfomation appeared to occur by separate nucleation.View full abstractDownload PDF (1582K) -
Yasutaka Okada, Kunihiko Yoshikawa, Teruo Yukitoshi1981 Volume 45 Issue 5 Pages 496-502
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSensitization of Ni-based Alloy 600 was discussed by means of magnetic susceptibility measurements. In Alloy 600, the magnetic susceptibility responds quite sensitively to the chromium content. Magnetic susceptibility of Alloy 600 increases with the sensitization as the result of the formation of chromium carbide precipitates. Alloy 600 with various carbon contents was sensitized at temperatures from 773 to 1073 K after solution annealing and the magnetic susceptibility measurements were carried out over the temperature range from 123 to 773 K.
The results are as follows: (1) Throughout the sensitization and recovery stage, the magnetic susceptibility was consistent with the result of 40%HNO3 test. (2) Sensitized Alloy 600 showed an increase of the Curie point up to a temperature of 523 K compared with that in the solution annealed condition. (3) From the increase of the Curie point at higher temperature, the chromium content in the chromium depleted region was determined. The minimum chromium content was estimated at less than 3% in the most sensitized condition and the chromium content increased in the recovery stage.View full abstractDownload PDF (488K) -
Hideo Ike, Hirobumi Okabe, Takashi Ohta1981 Volume 45 Issue 5 Pages 503-509
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHigh temperature oxidation has been made on four steels of type 430, i.e. Fe-16.6Cr (430-A), Fe-16.2Cr-0.4Ti (430-B), Fe-16.2Cr-0.3Zr (430-C) and Fe-17.6Cr-0.5Al (430-D) in wet oxygen containing up to 10 vol%H2O as well as in dry one between 1173 and 1473 K for 86.4 ks (24 h). 430-A has shown protections at 1173 K, 430-B at 1273 K, and 430-C and 430-D at 1373 K, irrespective of the environmental humidity. Above these temperatures, the mass gain curve of each steel shows breakaway, and the initiation and growth of the breakaway is accelerated by water vapour. The scale structures are duplicated and basically similar to each other, i.e. the outer layer being of type MnCr2O4 and the inner layer is of type (Fe, Cr)2O3. When steels contain Ti, Zr and Al, respectively, the internal oxidation of each element occurs. Zr and Al have shown strong contributions to adhesion of the scales. On the contrary, no contribution from the internal oxidation particles of Ti to the adhesion of the scales formed on 430-B has been observed.View full abstractDownload PDF (1194K) -
Hideo Ike, Hirobumi Okabe, Eiji Tsuji1981 Volume 45 Issue 5 Pages 510-516
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHigh temperature oxidation has been made on four chromium steels, i.e. Fe-13.7Cr-0.2Al (405), Fe-11.9Cr-0.7Ti (409-A), Fe-11.8Cr-0.4Ti (409-B) and Fe-12.2Cr (410), in wet oxygen containing up to 10 vol%H2O as well as in dry one between 1173 and 1473 K for 86.4 ks (24 h). All steels show protections at 1173 K irrespective of moisture in the atmosphere except for 405 which has shown a slight degree of breakaway in 10 vol%H2O/O2 mixture. All but 409-B are affected by water vapour at 1273 K in such a way that the oxidation rates are substantially increased and the induction periods before the begining of breakaway are accelerated. The same situation is observed at 1373 K for 409-B which contains a higher content of Si than the other steels tested. The scale structures are double-layered and basically similar to each other, i.e. the outer layer being of type MnCr2O4 and the inner layer is of type (Fe,Cr)2O3. When the steels contain Ti, the internal oxidation of the element occurs. However, no contribution to the adhesion of the scales due to the dispersed internal particles has been observed.View full abstractDownload PDF (1107K) -
Fumihiko Ishida1981 Volume 45 Issue 5 Pages 517-524
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of the addition of third elements on the critical current density, Jc, of the Nb-60 at%Ti alloy have been investigated. As the third elements, Si, Ge, Ni, O, N, C, Cu, Co, Fe, Cr, Pd, Pt, Zr, Al, Mo, V, W, Au, Ag, Sn, Zn, Pb, Bi, Ta and Hf were added up to a few at%. The specimens were reduced 98.44% in area by cold-drawing and then aged at 673 K or 773 K. The results are summarized as follows:
(1) The addition of Si, Ge, Ni, O or N to the Nb-Ti alloy increases the Jc of the aged specimens by a factor of ten.
(2) The addition of Si, Ge, Ni, O or N produces a finer and more uniform distribution of α-precipitates which act as pinning points of flux lines, thus resulting in the increase in Jc.
(3) The hardness of the Nb-Ti alloy is increased by addition of the third elements. It is difficult to cold-draw the alloys containing more than 2 at%O or N and more than 3 at%Si, Ge or Ni.View full abstractDownload PDF (1326K) -
Fumihiko Ishida1981 Volume 45 Issue 5 Pages 525-533
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of aging on the critical current density, Jc, and the structure have been investigated for Nb-Ti-Si alloys containing less than 2 at%Si. The results are summarized as follows:
(1) The maximum value of Jc on the isothermal aging curve increases and shifts to a shorter time with increasing Si content or amount of cold-reduction prior to aging. By means of aging at 773∼823 K for 3.6∼18 ks after cold-working by 98∼99% reduction in area, the Jc of alloys with more than 0.5 at%Si content reaches a value as high as 1×109 A/m2 at 5.0T.
(2) The solubility of Si in the Nb-Ti solid solution containing about 60 at%Ti is 0.5 at% at 1373 K, and the precipitation of α-phase is suppressed by the addition of Si. On aging at 823 K for a time as long as 6.48 Ms, the Widmanstatten-like transitional phase precipitates with habit planes parallel to {100}β.
(3) In specimens aged after cold-working, α-precipitates are spherical and become finer with increasing Si content or amount of cold-reduction prior to aging, thus causing the increase in Jc.
(4) The tensile strength of the Nb-Ti-Si alloys increases with increasing Si content and it is difficult to cold-draw the alloys with more than 3 at%Si.
(5) The most optimum composition for a superconducting magnet material in the alloy consists of 30 to 50 at%Nb, 50 to 70 at%Ti and 0.5 to 2 at%Si.
(6) The best Jc property is obtained for Nb-63.4 at%Ti-1.0 at%Si alloy cold-worked by 99.99% reduction in area and subsequently aged at 773 K for 3.6 ks. The Jc values of this specimen at 4.2 K are 1.4×109 A/m2 at 5.0T, 8.6×108 A/m2 at 7.0T and 4.6×108 A/m2 at 9.0T, respectively. The upper critical field of this specimen is 12.0T at 4.2 K, its critical temperature being 8.6 K.View full abstractDownload PDF (1742K) -
Naotsugu Inakazu, Hisashi Yamamoto1981 Volume 45 Issue 5 Pages 533-541
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to find the relation between deformation band formation and the substructure of copper single crystals during drawing, the axial orientation changes were investigated by means of the pole figure determination and transmission electron microscopy.
The forming process of the deformation band developed in the central region of the specimens depended on the initial orientation, and the axes rotated toward ⟨100⟩ and/or ⟨111⟩ orientations. At low reductions, the substructure consisted of cells, about 0.5 μm in diameter, up to 50% of area reduction, and these cells were elongated in the drawing direction. The development of the microband was related to the initial orientation of specimen, that is, in the case of the specimen accompanied with the ⟨111⟩ orientation, these microbands consisted of a sharp boundary, while in the case of the specimen rotated toward ⟨100⟩ orientation, these boundaries were lacking in clearness.
Consequently, it was confirmed that the transition region among the deformation bands consisted of a bundle of microbands having a misorientation of about 2°, and therefore the transition region was formed with low-angle boundaries.View full abstractDownload PDF (1018K) -
Seiichi Iwata, Hiroshi Yamamoto, Akira Kikuchi, Kensuke Nakata1981 Volume 45 Issue 5 Pages 542-543
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (128K) -
Seiichi Iwata, Akitoshi Ishizaka1981 Volume 45 Issue 5 Pages 544-545
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (135K)
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