Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Volume 43 , Issue 5
Showing 1-18 articles out of 18 articles from the selected issue
  • Hakaru Masumoto, Kiyoshi Watanabe, Masao Mitera
    1979 Volume 43 Issue 5 Pages 361-363
    Published: 1979
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Measurements of rigidity modulus, thermal expansion, magnetization at 293∼573 K and hardness at room temperature have been carried out for annealed Mn-Ga alloys.
    The results show that Mn-21.0∼26.8 at%Ga alloys of the ε phase and the β+ε phase cooled slowly from 1173 K have distinct anomalies at the temperatures corresponding to the Néel points in both the rigidity modulus vs temperature curves and the thermal expansion curves. Thus the rigidity modulus curves exhibit a small maximum below the Néel point TN, showing a typical Elinvar characteristic near room temperature. The thermal expansion coefficient becomes smaller below TN.
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  • Hiroaki Kurishita, Sadakichi Kitajima
    1979 Volume 43 Issue 5 Pages 364-371
    Published: 1979
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Using an etch pit technique, which is applicable to distinguish between edge and 30°-screw dislocations, the shear stress τ0 necessary to move grown-in dislocations in highly perfect copper crystals is studied in relation to the condition of the crystal surface. The main results obtained are as follows: (i) Surface removal results in the remarkable reduction of τ0, which is more conspicuous in 30°-screw dislocation than in the edge one. (ii) Both edge and 30°-screw dislocations become very mobile at low stress levels with the reduction of partial pressure of O2 in the annealing atmosphere. (iii) Neither the surface-step formation in the motion of dislocations with screw character nor jogs along those with the edge character are found to have an important effect on τ0.
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  • Hiroaki Kurishita, Sadakichi Kitajima
    1979 Volume 43 Issue 5 Pages 372-380
    Published: 1979
    Released: April 04, 2008
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    Motion of dislocations after their breakaway from as-annealed positions, is studied in highly perfect copper crystals at stress levels less than the shear stress τm needed for dislocation multiplication, using an etch-pit technique. The main results are as follows: (i) Waiting time tw required for the edge dislocation to jump over the obstacle by a thermally activated process, is experimentally shown to range from 3 to 5 s under effective shear stresses of 5.4 to 9.5×104 Pa at room temperature, whose values correspond to the activation energies of about 6∼7×10−20 J. Forest dislocations are not responsible for this process. (ii) In contrast with edge dislocations, the initial and final positions (etch-pits on the {111} surface) of moved 30°-screw dislocations are often out of a straight line parallel to ⟨110⟩. This is due to the disappearance of the large super-jog from the {111} surface by its conservative motion under an applied stress. (iii) The distance moved by the edge dislocation is much larger than that by the 30°-screw one.
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  • Seiichi Iwata, Akitoshi Ishizaka
    1979 Volume 43 Issue 5 Pages 380-388
    Published: 1979
    Released: April 04, 2008
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    This study concerns the measurement of the true chemical shift for Si2p electrons emitted from thermally oxidized Si. Experiments were carried out to measure the chemical shifts for 1∼5 nm-thick thermally oxidized films on Si for various X-ray exposure times, oxide thicknesses, and X-ray intensities. The Si2p chemical shift was observed to range from 3.5 to 4.8 eV for the changes in the experimental conditions just mentioned. It was found from the chemical shift measurements for various X-ray exposure times that: (1) the shift increased with the X-ray exposure time, (2) this result was reproducible for the same specimen, and (3) the same shifts in the same direction were observed for Si2p and O1s electrons. From these results, it was concluded that there was electric charging effect in the chemical shift measurements of these thin insulating films on Si. The attempts were next made to obtain the true chemical shift with the help of theoretical calculations of the charge distribution and the surface potential change caused by X-radiation. It was shown, from the extrapolation of the chemical shift value to zero oxide thickness or to zero X-ray intensity, that the true Si2p chemical shift for thin thermally oxidized Si films was 3.0 eV. This meant that the surface potential changed by 0.5∼1.8 eV due to electric charging of the oxide film during ESCA measurement.
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  • Seiichi Iwata, Akitoshi Ishizaka
    1979 Volume 43 Issue 5 Pages 388-392
    Published: 1979
    Released: April 04, 2008
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    This study deals with the electric charging of thin insulating films by X-radiation during ESCA measurements. The effect of charging on the value of the kinetic energy for electrons emitted from the specimen surface was obtained on the assumption that there is no charging when either the X-ray intensity or thickness of the insulating film is zero. By measuring the kinetic energy for various X-ray intensities and by extrapolating to zero intensity, it was found that the kinetic energy of C1s electrons emitted from an adsorption layer on Cu shifted to a lower value by as much as 2 eV. It was also found from the X-ray intensity or thickness dependence of the kinetic energy that the true chemical shift for Si2p electrons from 1∼5 nm-thick thermal oxide films on Si was 3.0±0.2 eV and that the effect of charging amounted to 0.5∼1.8 eV for these oxide films.
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  • Itsuo Ishigami, Eiji Tsunasawa, Kyuhiko Yamanaka
    1979 Volume 43 Issue 5 Pages 392-399
    Published: 1979
    Released: April 04, 2008
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    Changes in the brightness of stainless steels surfaces with vacuum heating conditions were examined by use of a die-cooling method. In the die-cooling methed, specimens were cooled in vacuum on a water cooled die of the mild steel after being vacuum heated; consequently steel surfaces were restrained from being stained with quenchants on quenching. The brightness was measured using an optical microscope equipped with a silicon photocell. (1) In SUS 304 heated for 30 min under a pressure of 5.33 Pa, the oxide film formed on heating to 900°C disappeared gradually with increasing temperature to 1050°C; consequently the brightness increased from 27% at 950°C to 100% at 1050°C. An increase in temperature above 1050°C resulted in a decrease of the brightness owing to a surface roughening. The disappearance of the oxide film was explained in terms of its reduction by the solute carbon in steels, that is, Cr2O3+3C=2Cr+3CO. (2) In SUS 347, it was difficult for the oxide film to be reduced because of the much lower content of the solute carbon in the steel. (3) In other stainless steels of 0∼30 wt%Ni and 12∼27 wt%Cr, the types of steels were generally classified in the order of the difficulty in the reduction of films; heat resisting cast steels > austenitic stainless steels > martensitic and ferritic stainless steels. Essentially, the oxide films were more easily reduced for the steels, in which the C activity and hence the equilibrium CO pressure is higher.
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  • Takumi Sone, Eiji Tsunasawa, Kyuhiko Yamanaka
    1979 Volume 43 Issue 5 Pages 399-404
    Published: 1979
    Released: April 04, 2008
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    S15C steel was ion-softnitrided with N2-H2-CH4 gas mixtures of various compositions at 823 K for 14.4 ks under a pressure of 6.67×102 Pa. Then, the properties of the produced layer were investigated by means of micro-vickers hardness testing, X-ray diffraction, EPMA analysis and wear testing.
    \ oindentThe following results were obtained.
    (1) In the higher CH4 gas content in the atmosphere, the compound layer was thin (less than 2 μm) and the diffusion layer was shallow or did not exist. That region was approximately given by
    (This article is not displayable. Please see full text pdf.)
    \ oindentat 823 K under a pressure of 6.67×102 Pa.
    (2) The ε-Fe2−3 (CN) phase was formed easily by the addition of CH4 gas. The Fe3C phase was formed and the sooting appeared with increasing CH4 gas content in the atmosphere. In the lower N2 gas atmosphere, however, those occurred at the lower CH4 gas content.
    (3) The wear characteristic of the ion-softnitrided S15C steel little depended on the phase, thickness (about 7∼13 μm), nitrogen and carbon contents of the compound layer, and the ion-softnitrided S15C steel showed far better wear resistance than the normalized S15C steel. The amount of wear of the ion-softnitrided S15C steel was less than that of the ion-nitrided S15C steel at high speed and load.
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  • Yoshihiro Oya, Tomoo Suzuki, Yukio Ichinose
    1979 Volume 43 Issue 5 Pages 404-408
    Published: 1979
    Released: April 04, 2008
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    This paper describes the development of the “Thermoseed”, a thermally self-regulating implant for induction thermocoagulation of the brain lesions. The thermoseed should have a low Curie temperature and a high saturation magnetization that will cease heating at predetermined temperatures, i.e., 343∼373 K.
    In contrast to many nickel base alloys, the saturation magnetization of nickel is increased or kept constant by the additions of manganese and/or palladium in spite of the lowering of the Curie temperature. The Ni-Pd-Mn ternary system presented by Köster and Sallam has been re-examined, and the composition dependence of both the Curie temperature and the saturation magnetization has been determined in the ternary fcc solid solution range. The desired compositions for a thermoseed are selected as the intersection of ridge of the saturation magnetization and the contour of the desired Curie temperature.
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  • Kazuhiro Yoshihara, Masayasu Kurahashi, Kazuyoshi Nii
    1979 Volume 43 Issue 5 Pages 409-414
    Published: 1979
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The segregation behavior of sulfur, oxygen and phosphorus at the (100) surface of the iron single crystal, the bulk sulfur concentration of which had been adjusted to 23∼66 ppm, was investigated by using AES-LEED from the segregation kinetic point of view.
    When the sample was annealed between 973 and 1123 K in vacuum, sulfur, oxygen and phosphorus initially segregated to the surface. As the annealing was prolonged, however, the concentration of sulfur at the surface increased, and at first phosphorus and then oxygen disappeared from the surface. So finally only sulfur existed at the surface.
    This phenomenon can be explained as follows. At the first stage, sulfur, oxygen and phosphorus occupy surface sites simultaneously. The surface activities of these elements, however, are in the order of sulfur, oxygen, phosphorus. Therefore, as the concentration of sulfur at the surface increases, sulfur replaces first phosphorus and then oxygen. Finally, only sulfur occupies the surface sites.
    The concentration of sulfur at the surface increased in proportion to the annealing time and then reached a constant value. The segregation rate became greater as the bulk sulfur concentration increased.
    The activation energy of the segregation rate increased as the bulk sulfur concentration decreased. This is because sulfur is trapped by the impurities such as manganese and magnesium which have strong affinity for sulfur and this effect becomes more remarkable as the bulk sulfur concentration decreases.
    When the concentration of sulfur at the surface reached an equilibrium value, the structure of the surface was c(2×2) and two iron atoms combined with one sulfur atoms at the surface.
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  • Kazuhiro Yoshihara, Kazuyoshi Nii
    1979 Volume 43 Issue 5 Pages 414-419
    Published: 1979
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The iron single crystal, the bulk sulfur concentration of which had been adjusted between 23 ppm and 66 ppm, was heated at 1023 K in vacuum, and the segregation rate of sulfur at the (100) surface was measured with good reproducibility by using AES. The result was compared with the theoretical equation.
    Because the equilibrium concentration of sulfur at the surface was constant, unaffected by the bulk sulfur concentration and annealing temperatures, the number of the surface sites to which sulfur could segregate was assumed to be constant. Assuming further that the segregation rate is proportional to the number of vacant sites at the surface and the bulk concentration of the segregant beneath the surface, the theoretical equation of the segregation rate has been derived. This equation shows that at the early stage of segregation, the concentration at the surface increases in proportion to the annealing time, and that the segregation rate is proportional to the bulk concentration and independent of the diffusion coefficient of the segregant.
    From the experiments, the concentration of sulfur at the surface was observed to increase in proportion to the annealing time and then reached a constant value. The segregation rate became greater as the bulk sulfur concentration increased. This tendency coincides well with that of the theoretical equation.
    The concentration profile of the segregant near the surface influenced the segregation rate at the first stage. Therefore, in order to observe the segregation behavior with good reproducibility, it was necessary prior to measurements to sufficiently anneal the sample at the measuring temperature and sputter the surface by the argon ion until the concentration at the surface became equal to the bulk concentration.
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  • Jun-ichi Masuda
    1979 Volume 43 Issue 5 Pages 419-424
    Published: 1979
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Acoustic emission generated during tensile deformation of Corson alloys which are known as age-hardened copper alloys was studied.
    Continuous type acoustic signals were monitored. The mean voltage took a maximum at the yield point during the tension test. Acoustic energy per unit particle increased as the square of the distance between the centers of two neighboring particles increased. This suggests that the effective dislocation length against one precipitate particle is roughly proportional to the distance between the centers of two neighboring particles. The lower frequency ratio of acoustic energy at two different frequencies increased as the radius of the precipitate particle increased. This suggests that the effective distance of the dislocation movement, which can be regarded as the acoustic source, increases as the radius of the precipitate particle increases, and the diameter of the particle may be corresponding to the effective distance of dislocation movement which can be regarded as accoustic source. From the variation of mean voltages at two different frequencies during the tension test, it was suggested that micro yield occurred at the position of the smaller particle at a lower stress and the position of the larger particle at a higher stress.
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  • Tatsuhiko Ejima, Tsutomu Yamamura, Michio Kawashima
    1979 Volume 43 Issue 5 Pages 425-433
    Published: 1979
    Released: April 04, 2008
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    In order to clarify the relative importance of various factors for solute diffusion of impurity cations, the inter-diffusion coefficients of silver ion in molten alkali chlorides were determined by the use of capillary reservoir methods at the temperatures ranging from the melting points of solvent salts to 200 K above them.
    The results obtained can be summarized as follows:
    (1) The temperature dependence of the inter-diffusion coefficient of Ag+ ion was well represented by an equation of Arrhenius type. Pre-exponential term and the apparent activation energy for diffusion were determined by the use the of the least square method.
    (2) The applicability of Stokes-Einstein equation was examined. Diffusion coefficient of Ag+ ion increased linearly with increasing values of kT⁄ηr, where η is the viscosity of the solvent salt. The radius of the silver ion in molten chlorides was considered to be nearly equal to that of the sodium ion.
    (3) A linear relation was found between the molar volume of solvent salts and the vaule of D⁄(TM)1⁄2 in the temperature range wherein the diffusion coefficients were measured. The diffusive movement of solute cations was considered to be correlated with that of solvent cations.
    (4) The polarization energy of anion as well as the energy of hole formation is an important factor controlling the diffusive movement of the solute cation in molten alkali metal chlorides.
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  • Mitsuhiko Yoshida, Hajime Suto
    1979 Volume 43 Issue 5 Pages 433-439
    Published: 1979
    Released: April 04, 2008
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    In order to discuss problems on the various properties of tool steels, the knowledge on impurity segregation to γ-boundary and carbide/γ-interface is often required, but the information has not been available. In this paper, we deal with the segregation of P,C and Cr to the γ-boundary and to the carbide/γ-interface in high C·Cr steels. 1.0%C-7%Cr (M7C3 series) and 0.5%C-17%Cr (M23C6 series) steels containing various amounts of P were quenched from the temperature of the γ single phase region or of two-phase (γ and grain-boundary carbide) region. These specimens were fractured intergranularly in vacuo, and the fracture surfaces were analysed by AES. The results are as follows:
    (1) Cr,C and P segregated to γ-boundary and the segregation levels of Cr and C were not affected by P content in bulk.
    (2) The segregation of P to M7C3 (or M23C6)/γ-interfaces was as expected but Cr and C “negatively” segregated from these interfaces.
    (3) The segregation level of P in γ-boundary decreased with increasing Cr content in bulk. The segregation level of P in M3C (or Fe3C)/γ-interface was higher than those in M7C3/γ- and M23C6/γ-interfaces.
    These results were discussed mainly from the viewpoints of chemical interaction between solutes and boundary and between solutes.
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  • Yasuhide Tsu, Yutaka Shiraishi, Katsutoshi Takano, Shunroku Watanabe
    1979 Volume 43 Issue 5 Pages 439-446
    Published: 1979
    Released: April 04, 2008
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    The velocity of ultrasonic waves in liquid tin, lead and zinc has been measured in the temperature range from the melting points to the temperatures about 300 K higher than the melting points by using the double transducer pulse method at 2 MHz. The relation between the velocity of ultrasonic waves and the experimental temperature could be represented by a straight line having a negative temperature coefficient over the entire range of experimental temperatures for these liquid metals. The adiabatic and isothermal compressibilities were calculated at their melting points from the obtained results and other thermodynamic data.
    In comparison of the isothermal compressibility calculated by simple models with the experimental one, it was shown that the result by Ascarelli’s model was in good agreement with the experimental value but a hard sphere model did not yield any satisfactory result for these liquid metals.
    From these results, it was concluded that the contribution of free electron gas to the compressibility of these liquid metals cannot be neglected.
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  • Fumihiko Ishida, Toshio Doi
    1979 Volume 43 Issue 5 Pages 446-451
    Published: 1979
    Released: April 04, 2008
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    The effect of aging temperature, cold-reduction prior to aging, O2 content and composition on the variation in the critical current density, Jc, by isothermal aging was investigated in heavily cold-worked Nb-Ti-Zr alloys on the Nb-Ti side. The results are summarized as follows:
    (1) When these alloys are aged isothermally at temperatures from 350 to 500°C, Jc increases initially, reaches a maximum value and then decreases. Increase in Jc of three orders of magnitude is possible as a result of aging.
    (2) The maximum value of Jc on the isothermal aging curve becomes higher at a lower aging temperature, at a less cold-reduction prior to aging or with a higher O2 content.
    (3) The Jc of aged alloy becomes a maximum in composition containing 35 at%Nb, 60 to 65 at%Ti and less than 5 at%Zr.
    (4) The maximum value of Jc was obtained for Nb-60.0 at%Ti-5.0 at%Zr alloy containing 1200 wt ppm O2, aged at 350°C for 330 h after 98.44% cold-reduction. The values of Jc at 4.2 K were 2.4×109 A/m2 at 5.0 T, 1.1×109 A/m2 at 7.0 T and 3.0×108 A/m2 at 9.0 T, respectively. The upper critical field of this specimen was 11.3 T at 4.2 K and its critical temperature was 8.6 K.
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  • Fumihiko Ishida, Keisuke Matsuura, Toshio Doi
    1979 Volume 43 Issue 5 Pages 452-460
    Published: 1979
    Released: April 04, 2008
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    The variation in the microstructure by aging was investigated by means of electron microscopy in heavily cold-worked Nb-Ti-Zr alloys on the Nb-Ti side. The variations in the critical current density, Jc, by aging reported in the former paper were correlated with the microstructure changes observed in the present study, and the pinning mechanism was examined. The results are summarized as follows:
    (1) On aging at 500°C, an equilibrium phase α precipitates directly from a β phase, whereas on aging at 350°C, a transition phase ω is formed prior to the precipitation of the α phase.
    (2) The α phase takes a hexagonal closed-packed structure with lattice parameters a=0.296 and c=0.471 nm and has the orientation relationships (0001)α\varparallel(1\bar10)β and [11\bar20]α\varparallel[111]β. The ω phase takes a hexagonal structure with lattice parameters a=0.463 and c=0.284 nm and has the orientation relationships (\bar2110)ω\varparallel(1\bar10)β and [0001]ω\varparallel[111]β.
    (3) When the heavily cold-drawn wire with fibered structure is aged, precipitation occurs preferentially at the fiber boundaries and these precipitates grow coarser than those within the fibers. So,the structure of aged wire grows coarser with increasing cold-reduction prior to aging.
    (4) In the precipitation of the α phase from the β supersaturated solid solution, the precipitates become finer and numerous at a lower aging temperature or with a higher solute Ti or O2 content in the β phase.
    (5) The effective fluxoid pinners are the α and ω, precipitates in specimens aged after cold-working. The highest Jc is obtained by aging which produces a fine dispersion of precipitates. The Jc reaches a maximum value as the size of precipitate is on the order of 10 nm.
    (6) The peak of the curve in pinning force density versus applied magnetic field increases in height and shifts to lower field with isothermal aging at relatively low temperatures (\lesssim400°C).
    (7) It is found that Kramer’s model seems to account for flux pinning in specimens with a fine distribution of precipitates.
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  • Shigeaki Takajo, Ichiya Endo, Yoshihiro Kajinaga, Shunji Itoh
    1979 Volume 43 Issue 5 Pages 461-467
    Published: 1979
    Released: April 04, 2008
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    The complex permeability was calculated and compared with measured values for packed metal powders, in order to clarify the heating mechanism in the deoxidation process of water-atomized steel powders through induction heating in vacuum.
    The calculation was carried out separately on “unsintered” and “completely sintered” packed powders based on different models. The former model restricted eddy currents within individual particles, where the electromagnetic field distribution in an isolated particle was first solved strictly, and then modified in order to take into account the magnetostatic interaction between particles. The latter model assumed the predomination of inter-particle eddy currents and led to the heat generation mechanism similar to that of uniform materials. A more general form for “incompletely sintered” packed powders was obtained as a unification of the above two extremes introducing a parameter for the completeness of sintering.
    The calculated results were compared with the measurements in the frequency range of 1∼500 kHz on the unsintered and sintered packed powders of copper and iron with spherical particle shapes. The comparison revealed superior coincidence at various stages of sintering.
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  • Mikihiko Ito, Tomoaki Sakurai, Kimiyoshi Goto
    1979 Volume 43 Issue 5 Pages 468-469
    Published: 1979
    Released: April 04, 2008
    JOURNALS FREE ACCESS
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