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Volume 45, Issue 4
Displaying 1-17 of 17 articles from this issue
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Takemori Takayama, Myeong Yong Wey, Taiji Nishizawa1981 Volume 45 Issue 4 Pages 341-346
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSolubility of Al, Ti, Mo and W in fcc Co was determined by X-ray diffraction and micro-probe analysis. It was observed that the solubility of these elements was reduced considerably near and below the Curie temperature. The reduction was conspicuous for the alloying elements which reduced the Curie temperature effectively. These results were similar to those found in bcc Fe alloys. Thermodynamic analysis was performed on the solubility data, taking into account the effect of magnetic transition on the free energy of fcc Co-X solid solution.View full abstractDownload PDF (369K) -
Masayuki Hasaka, Hiromichi Nakashima, Kensuke Oki1981 Volume 45 Issue 4 Pages 347-353
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis paper describes the light-microscopic observations of polystyrene latexes whose particles have spherical bodies with two different diameters: d and 1.4∼1.9d. It is shown that polystyrene latexes are of use to simulate real structures in intermetallic compounds.
An amorphous state appeared for a few hours after stirring or vibrating latexes, and subsequently, the Laves phase nucleated and grew by the Brownian motion of particles when the diameters were d and 1.4∼1.7d. The Laves phase of the MgCu2 or MgZn2 type was observed, containing some lattice defects such as grain boundaries, dislocations, vacancies, or miss-arranged particles.View full abstractDownload PDF (654K) -
Kensuke Oki, Shin-ichi Towata, Masaharu Tamiya, Tetsuo Eguchi1981 Volume 45 Issue 4 Pages 354-359
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe process of atomic reordering of cold-worked Fe-Al alloys containing about 25 to 35 at%Al during isothermal annealing has been investigated using Mössbauer spectroscopy. Mössbauer spectra from the specimens filed and annealed were observed at each stage of annealing and analyzed to obtain the distribution function of the internal magnetic field in the alloys. Furthermore, for the alloy with 24.9 at%Al the information on the nearest neighbor configurations of constituent atoms could also be obtained directly from the Mössbauer spectra by assuming the Gaussian distribution function of hyperfine field acting on iron atoms with various number of iron neighbors, and the detailed process of reordering was clarified.
The alloy with the DO3 type of order, which is either weakly magnetic or nonmagnetic depending on the composition, became strongly magnetic by filing. The alloy as-filed was much complicated in structure and the atomic configuration seemed to be distinctly different from that of the thermally disordered state. The alloy reordered very slowly in the course of annealing by way of perfect disorder and B2 type of order. The ordered alloy with B2 symmetry, which is nonmagnetic, was partially disordered by filing and changed into a weakly magnetic state. The alloy recovered promptly to its initial state by low temperature annealing.View full abstractDownload PDF (449K) -
Katsuhiko Ishiguro, Teiichi Homma1981 Volume 45 Issue 4 Pages 360-367
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAuger spectra were investigated for both oxide and metallic states of some transition elements in order to obtain quantitative information about the composition and structure of thin oxide films formed on metals and alloys.
The peak shape for oxides was compared systematically with that for metals, and the effect of the change in the peak shape on the relative sensitivity factor by oxidation was discussed.
The oxides investigated were prepared by thermal oxidation of pure metals, ranging from Ti to Zn of the first row in the periodic table, and their Auger spectra in LMM transition were observed in a couple of modes as differential [dN⁄dE] and integral [N(E)]. It was shown that the spectra obtained exhibited a wide variety of width in the profile and of the relative intensities of their spectra of the LMM groups which involve valence band transitions depending on the oxidation state. But for the oxide states of Cu and Zn, the width change due to broadening was negligibly small. The relative sensitivity factors, based on pure metal, decreased for the oxide peak which exhibited broadening in the diffrential mode while in the integral mode it tended to increase. Though the shape of the oxygen spectra showed differences in minute detail, the width of the main peak was not changed considerably except for the case of ZnO.
The possibility of estimating the variation of the composition with depth and of determining the oxide/metal interface position from the AES data has been pointed out.View full abstractDownload PDF (507K) -
Tatsuhiko Ejima, Yuzuru Sato, Akio Ando, Teruhiko Asakawa1981 Volume 45 Issue 4 Pages 368-373
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDensity of MgCl2-CsCl binary melt has been measured over the temperature range of liquidus to about 1200 K by means of the manometric method using a transparent furnace and U-type manometer. The results obtained are summarized as follows:
The density increases monotonously with increasing CsCl content. The expansion coefficient of pure MgCl2 is significantly small, but that of the binary melt increases to about 30 mol%CsCl. The molar volume deviates positively from the additivity over the whole range of composition, and its deviation shows a maximum at about 65 mol%CsCl which corresponds nearly to the stoichiometric composition of the compound Cs2MgCl4. In the binary melt, the partial molar volume of MgCl2 increases steeply with increasing CsCl content in the composition range of more than 50 mol%CsCl, while that of CsCl exhibits a maximum at about 30 mol%CsCl. The volumetric behavior of the melt was explained in terms of the model which describes the constitution of ionic species including the MgCl42− complex anion in the melt.
The molar volume and expansion coefficient of each compound included in the melt were estimated by using the model of construction of the melt containing MgCl2 on the assumption of the additivity among the volumes of ionic species.View full abstractDownload PDF (517K) -
Tadakazu Ohnishi, Kenji Higashi, Yoshizo Nakatani1981 Volume 45 Issue 4 Pages 373-378
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn the conventional aging of Al-8%Mg alloy, the hydrogen embrittlement and the decrease of stress corrosion cracking life by hydrogen permeation are markedly produced in the hardening region of aging process. The step aging hardly alters these behaviors, because this treatment brings about an insignificant change in the microstructure. The thermo-mechanical treatment effectively depresses the embrittlement and the decrease of life by hydrogen permeation over the whole range of testing conditions used in this study. This effect seems to be attributable to a depression of precipitation in the grain boundary at the final aging and to an introduction of the dislocation structure by the intermediate deformation. The effect of dislocation structure and the role of dislocation movement in the hydrogen transport to the critical region of cracking are discussed.View full abstractDownload PDF (648K) -
Katsuro Kuroki, K\={o}hei Fukawa, Toshiya Wada1981 Volume 45 Issue 4 Pages 379-383
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSArtificial domain control has been applied to grain oriented silicon steel sheets. Lines are scratched on the surface of the sheets, with a rotary ball of 0.7 mm diameter on one side of the sheet. Directions of scratching 0°(rolling), 10°, 20°, 30°, 45°, 60°, and 90°(cross rolling) from the rolling direction. The interval of the lines is 10 mm. Scratching parallel to the cross rolling direction improves the total loss of the rolling direction and causes the refinement of the 180° domain which is the main domain in the (110)[001] oriented silicon steel. Scratching parallel to the rolling direction improves the total loss of the cross rolling direction, and improves that of the 45° direction slightly. Scratching parallel to 20° to 60° directions improves the total loss of both the rolling and cross rolling directions. The improvement of the total loss due to scratching is considered to be caused by slight local plastic deformation produced by scratching.View full abstractDownload PDF (783K) -
K\={o}hei Fukawa1981 Volume 45 Issue 4 Pages 384-388
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWe have analyzed the residual internal stress caused by ball scratching on the surface of grain oriented Si-steel sheets, using a finite element method under the assumptions of (1) isotropic elastic-plastic materials, (2) plane strain, and (3) no bending.
The results are as follows: (1) the tensile stress perpendicular to the surface exists in the neighbourhood of the top surface and the bottom surface under the scratch, and (2) in the other region, tensile stress parallel to the surface exists in the direction perpendicular to the scratch. These results explain well the domain patterns observed by many investigators.View full abstractDownload PDF (407K) -
K\={o}hei Fukawa1981 Volume 45 Issue 4 Pages 388-394
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWe measured the wattlosses and observed the domain structures of knife-scratched grain oriented silicon steel single crystals, comparing to those of ball-scratching, and discussed the distribution of stresses caused by the scratching, and the reasons why the watt-loss decreases by the scratching and after stress-relief annealing.
The results obtained are as follows: (1) The distribution of residual internal stress caused by the knife-scratching is the same as that of ball-scratching, that is, the tensions perpendicular to the surface exist in the neighlourhood of top surface and bottom surface just beneath the scratch line, but the region of the stresses caused by the knife scratching is narrower than that by the ball scratching. (2) Degree of the deformation caused by the knife-scratching is much larger than that of the ball scratching. On annealing at 1073 K, the specimens with knife-scratching have recrystallized grains along the scratch-line and still have some residual stresses in it. On the other hand, the specimens with ball-scratching recovered to its original state. (3) In the case of knife-scratching, the decrease of wattloss is caused mainly by the internal stress, and the effect of the shape of groove is small. (4) In the case of knife-scratching, wattloss does not recover to the initial value on annealing at 1073 K. This is due to the shape of knife-scratching grooves, recrystallized grains along the grooves and residual internal stress. The effect of the former is much smaller than the sum of the latter two.View full abstractDownload PDF (1776K) -
Terunobu Miyazaki, Tesshu Miyahara, Akio Watanabe, Minoru Takahashi1981 Volume 45 Issue 4 Pages 395-404
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of isothermal annealing (200∼470°C, 30∼420 min) on permeability and core loss in the frequency range between 0.5 and 200 kHz have been studied for rapidly quenched amorphous Fe80P13C7 and Fe75Si15B10 alloys. The results obtained are summarized as follows:
(1) μ′ vs H curves measured show two maxima above 0.5 kHz in the as-prepared samples, and above several kHz in the annealed samples.
(2) Permeabilities measured at H=4 A/m, f=1 kHz in the as-prepared Fe80P13C7 and Fe75Si15B10 samples are (0.4∼1)×4π×10−4 H/m and (0.7∼1.5)×4π×10−4 H/m, respectively.
(3) Core losses measured at Bm=0.1 T, f=1 kHz in the as-prepared Fe80P13C7 and Fe75Si15B10 samples are 3∼6 J/m3 and 4∼6 J/m3, respectively.
(4) The optimum annealing condition to improve initial permeability and to decrease a core loss is annealing at 300∼350°C for Fe80P13C7 alloy and at 400∼470°C for Fe75Si15B10 alloy for several tens of min.
(5) After annealing in the above condition, μ′(4 A/m) increases 3∼4 times and the core loss decreases to approximately one-half those of the as-prepared samples for both alloys.
On the assumption that soft and hard magnetic regions exist in the as-prepared amorphous samples, the two maxima in μ′ vs H curve and also the anomaly in lnW vs lnBm can be explained.
About 85∼90% of the core loss measured is the eddy current loss. If we assume that the number of domain wall increases with increasing the frequency, the frequency dependence of eddy current loss can be explained by the plane wall model proposed by Pry and Bean.View full abstractDownload PDF (1291K) -
Teruo Uno, Yoshio Baba1981 Volume 45 Issue 4 Pages 405-410
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHigh purity Al-Mg-Si base alloys often exhibit low tensile ductility and typical grain boundary fracture occurs when aged to maximum strength levels. The influence of cold work and aging on the ductility and the fracture behaviour of high purity Al-Mg-Si base alloys has been investigated to prevent the grain boundary fracture and to improve the low ductility of the alloys. Marked improvement in the ductility of coarse grained alloys can be attained by proper cold work and aging, and the fracture mode changes from brittle grain boundary fracture to ductile transgrannular fracture. These phenomena are observed only in the coarse grained alloys and not in the fine grained alloy containing Cr. Preaging treatment after quenching is undesirable because of a decrease of the ductility. Marked improvement in the ductility is attributed to the absence of PFZ along grain boundaries, the suppression of coarse grain boundary precipitates and the precipitation of coarse intermediate precipitates in the matrix.View full abstractDownload PDF (880K) -
Shiro Kohara, Norio Muto1981 Volume 45 Issue 4 Pages 411-416
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe compatibility of SiC fibers with aluminum was investigated. The SiC fibers made from an organosilicon polymer was used in the present study. The fiber specimens were aluminum-coated by vacuum evaporation and heat treated at temperatures 673 to 873 K for 90 ks, or 973 to 1373 K for 1.8 ks in an argon atmosphere. Then, the fiber specimens were tensile tested at room temperature.
For the solid state aluminum, the SiC fibers showed no loss in tensile strength after the heat treatments at 673 to 773 K, but showed a slight degradation in tensile strength after the heat treatment at 873 K. For the liquid state aluminum, the SiC fibers showed a noticeable degradation in tensile strength after the heat treatments at temperatures higher than 973 K. However, the degradation in tensile strength was decreased in the solid and the liquid state by alloying Si with aluminum.View full abstractDownload PDF (460K) -
Mitsuo Niinomi, Yukinao Suzuki, Yoshisada Ueda1981 Volume 45 Issue 4 Pages 416-424
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCommercial pure iron, S45C, Fe-Cr, Fe-Si and Fe-C alloys were dipped into molten aluminum (99.8%) mostly at 1073 K and rotated at various speeds for various times. Then the alloy layer formed on each alloy was examined and the dissolution process of these alloys was studied. The thickness of the alloy layers became thinner with increasing rotating speed. With regard to the composition of the alloy layers, Fe2Al5 occupied the major portion in the same manner as under the static condition. The shape of the alloy layers formed on commercial pure iron, Fe-Cr and Fe-Si alloys changed from tounge-like to band-like as the rotating speed increased. For Fe-C alloy, the alloy layer is band-like at every rotating speed.
The dissolution rate of each alloy layer increased as the rotating speed increased. As under the static condition, the dissolution resistance against molten aluminum is the highest in Fe-C alloy and is the lowest in Fe-Si alloy. The dissolution process of commercial pure iron, S45C, Fe-Cr and Fe-Si alloys is controlled by the diffusion of Fe in molten aluminum. Moreover, in commercial pure iron. Fe-Cr and Fe-Si alloys, the dissolution is accelerated by natural convection and flaking of the alloy layer at lower rotating speed, while accelerated by flaking of the alloy layer and mechanical errosion by molten aluminum or by turblent flow near the rugged surface of alloys at higher rotating speed. The dissolution of Fe-C alloy, however, probably be controlled by the chemical reaction or mass transfer in the alloy layer and the diffusion of Fe in molten aluminum.View full abstractDownload PDF (1075K) -
Itsuo Ohnaka, Kouji Nishii, Tatsuichi Fukusako1981 Volume 45 Issue 4 Pages 424-432
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to make clear the formation mechanism of surface segregation of Al-4.5%Cu ingot cast in a steel mold, the solidifying ingot surface was observed directly. Further the effect of cooling and heating the solidifying ingot surface on the segregation was examined with SEM, EPMA and metallographic techniques. The experiment revealed that the solidifying ingot surface can be covered with a liquid layer, the liquid phase cannot move in the dendrite network of higher fraction solid than about 0.85, and weak water spray cooling of the surface can cause a heavy surface segregation. The latter phenomenon, which is important in the DC casting, seems to be caused by destruction of the balance between aluminostatic pressure and surface tension of oxide film supporting the surface liquid layer. This destruction is due to boiling of water on the surface. It is concluded that the formation of surface segregation can be explained by the squeeze out of interdendritic solute-enriched liquid into the surface layer by aluminostatic pressure, the growth of the α phase towards the mold face in the liquid layer, and the movement of the liquid phase on the surface into the interior of the ingot by solidification shrinkage.View full abstractDownload PDF (1575K) -
Etsuo Ohtsuki, Tomohisa Kito, Yoshimichi Masuda1981 Volume 45 Issue 4 Pages 432-437
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to determine the factors controlling the bend strength of sintered WC-Co alloys, the transverse rupture test and fractography have been performed on 9 kinds of alloys. By the choice of the length of the minor axis of the ellipse inscribed in the cross section of a defect, a, as the size of the fracture-initiating defect, two types of relationships were found to hold between nominal stress, σn, acting on the defect and the defect size. When the relevant defect size was larger than a critical size, ac, the nominal stress was inversely proportional to the root of the defect size, and the gradient of σn vs Y⁄\sqrtπa was equal to fracture toughness KIC of the alloys. (Y: Geometrical factor of defect.) On the other hand, when the defect size was smaller than the critical size, the nominal stress became independent of the defect size. Fracture toughness of the alloys was found to be proportional to the cobalt content and it was considerably influenced by the carbon content.View full abstractDownload PDF (470K) -
Kenzo Hanawa, Zenshiro Hara, Kiyoaki Akechi1981 Volume 45 Issue 4 Pages 438-445
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSUsing an electric resistance sintering aparatus, 2∼5%C flake graphite cast iron powder compacts were heated very rapidly to melt the central part of the compacts and then cooled very rapidly in order to leave the pores in a white cast iron matrix. The pore-containing white cast irons were annealed at 873∼1323 K for 1.8 ks under dry hydrogen flow, and cooled in air or in a furnace. Nodular graphite was formed according to the pore distributions which existed before annealing. However, in the pore-free specimens remelted at 1723 K for 0.6 ks, nodular graphite was not formed. The formed nodular graphite was polycrystalline and the c-axis of all crystallites was radially oriented in a way similar to that of coventional nodular graphite crystallized in a melt. These results suggest that nodular graphite can be formed by annealing of the pore-containing white cast iron, made from any kinds of cast iron powder, irrespective of carbon contents. This is explained in terms of the gas bubble theory that graphite is precipitated in the pores.View full abstractDownload PDF (2262K) -
Seiichi Iwata1981 Volume 45 Issue 4 Pages 446-447
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (107K)
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