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Volume 52, Issue 8
Displaying 1-13 of 13 articles from this issue
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Kazuhito Kamei1988 Volume 52 Issue 8 Pages 743-748
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWith special attention to the fine structure of Ni film and the structure of Ni/α-Fe interface, the hetero-epitaxial growth of Ni electrodeposits on polycrystalline α-Fe has been studied mainly by transmission electron microscopy. Results obtained are: (1) Ni grows hetero-epitaxially even under such a high current density as 500 A/m2 on a cleaned substrate surface. (2) The crystallographic orientation relationship between Ni deposits and the substrate α-Fe is almost the same as that of the Kurdjumov-Sachs relationship i.e. (110)α\varparallel(111)Ni, [1\bar11]α\varparallel[1\bar10]Ni. (3) the Ni hetero-epitaxial film consists of columnar crystals which grow in the ⟨110⟩ direction and contains dislocations and stacking faults with high density. (4) These defects are introduced in order to decrease the elastic strain caused by the misfit between Ni and α-Fe at the interface, and the number of defects decreases with increasing film thickness.View full abstractDownload PDF (2521K) -
Hideyuki Ikeda, Hidehiko Matsuda1988 Volume 52 Issue 8 Pages 749-754
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPhase stability in a substitutional binary alloy with a high concentration of vacancies were studied by a Monte Carlo method in consideration of the role of vacancies. It is assumed that excess vacancies introduced by irradiation play a role in the radiation induced spinodal decomposition. The values of pairwise interaction energy parameters used here were determined by a quasi-equilibrium approximation in such a way that they elevated the spinodal temperature with increase of vacancy concentration in a pseudo-ternary alloy with the vacancies regarded as the third element.
As a result, the elevation of spinodal temperature were obtained when the ordering energy parameters between vacancy and other atoms were negative.View full abstractDownload PDF (917K) -
Takeshi Haga, T\={o}ru Noguchi1988 Volume 52 Issue 8 Pages 755-761
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe bending fatigue test was performed on Ni-Cr steel specimens tempered in the temper britteness temperature region. First, the S-N curve, fatigue limit, and crack growth rate were compared with those of the normally tempered material. Secondly, the fracture surfaces were investigated by means of electron microscopy and X-ray microanalysis.
The results were as follows:
(1) No significant decrease was observed in the fatigue limit, except for the specimen tempered at 773 K which was about 25% lower in the value than the normally tempered one.
(2) Quasi-cleavage fracture as well as the fatigue striation-like markings in the specimens tempered at 623 and 773 K was observed by SEM and TEM fractography. No quasicleavage fractures were observed either in the as-quenched specimen or the normally tempered specimen.
(3) EPMA line analysis showed some concentration of Cr on the fatigue fracture surfaces of the temper brittleness specimens.
(4) The difference in the effect of the temper brittleness on the crack propagation was observed in the 104 fatigue strength region, while no clear difference was obtained in the fatigue limit region.View full abstractDownload PDF (2651K) -
Shoji Goto, Toshio Mimura, Hideo Yoshinaga1988 Volume 52 Issue 8 Pages 762-770
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to clarify the effect of the colony boundary on the high-temperature strength of unidirectionally solidified lamellar-eutectic composite, seven kinds of eutectic Al-CuAl2 polycrystals with different colony sizes and single crystals without colony boundaries were prepared by unidirectional solidification. Polycrystals consisting of randomly oriented colonies were also prepared by casting. Their yield strengths were compared with each other by means of a compression test at strain rates from 2×10−5 s−1 to 5×10−3 s−1 and at temperatures from 523 K to 673 K.
It is found that the yield strength parallel to the growth direction of colonies is higher than that of single crystals, while the strength perpendicular to the growth direction is lower than that of single crystals. The strength for the random case is not much different from that for the perpendicular case. These facts are explained by the constraining effect of colony boundaries on the anisotropic deformation of colonies for the parallel case and by preferential shear deformation in boundary regions for the perpendicular case. The dependence of the yield strength on colony size, strain rate and temperature is also described.View full abstractDownload PDF (1482K) -
Seiichi Iwata, Naoki Yamamoto1988 Volume 52 Issue 8 Pages 771-779
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis study was carried out to find out the reasons for the discrepancies between the observed and expected carrier concentration dependences of kinetic energy of Si2p electrons from hydrofluoric acid treated Si as measured by ESCA. Experimentally, by changing the X-ray intensity and oxide thickness on Si, it was found that the above discrepancies are largely due to the effect of X-irradiation used for ESCA measurements. Theoretically, the electric potential distribution (band bending) near the Si surface due to X-irradiation was calculated by assuming a quasi-equilibrium state and using several simplifying assumptions. The changes in Si2p kinetic energies for various carrier concentrations caused by this band bending were then obtained in order to compare them with the experimental results. The calculated concentration dependence had all the features of the experimentally obtained results, and it was shown that the above discrepancies were due to two causes, namely, the increase in intrinsic carrier concentration near the surface (up to ∼10−6 m from the surface) due to X-irradiation and the electron emission from the region very near the surface (\lesssim10−8 m from the surface). These results show the importance of electric potential changes due to X-irradiation in the interpretation of obtained results, not only for insulators, but also for semiconductors. On the other hand, it is possible to obtain information on band bending and carrier concentration in the region very near the surface if measurements are carefully carried out.View full abstractDownload PDF (1436K) -
Takashi Watanabe, Hiromitsu Naito1988 Volume 52 Issue 8 Pages 780-785
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCorrosion characteristics of the open surface of a Ti-Pd(0.14) alloy have been studied in NaCl-HCl solutions of various concentrations. It has been confirmed that the Ti-Pd alloy shows markedly lower corrosion rates and improved corrosion resistance in comparison with pure titanium in these environments. The electrochemical behavior of the Ti-Pd alloy in these solutions suggests that palladium accumulates on the surface of the Ti-Pd alloy during the initial period of corrosion, the accumulation of palladium on the alloy surface being confirmed by GDS analysis. The corrosion protection is explained by the fact that a palladium enrichment on the surface accelerates the cathodic reaction due to lowering the hydrogen overvoltage, and consequently, shifts the corrosion potential of the alloy into the passive region of titanium. Therefore, the corrosion potential of the alloy is more noble than the critical potential for passivity of titanium.View full abstractDownload PDF (746K) -
Kiyoshi Nogi, Kazumi Ogino1988 Volume 52 Issue 8 Pages 786-791
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe wettability of reaction bonded SiC and hot pressed SiC by liquid pure metals such as Pb, Sn, Ge, Cu and Fe was investigated using the sessile drop method in Ar atmosphere.
Main results were as follows:
(1) Contact angles of liquid pure metals on SiC depended on the solubilities of Si and C in the liquid pure metals.
(2) The contact angles of liquid pure metals on the reaction bonded SiC which contained metallic Si differed from those on hot pressed SiC. It can be concluded that the higher the solubility of Si in liquid metals, the larger the difference in the contact angles on the reaction bonded SiC and on hot pressed SiC.
(3) Contact angle of liquid pure Ge on reaction bonded SiC showed a consderable temperature dependence and reached 0 deg. at a higher temperature. On the other hand, the higher contact angle on hot pressed SiC was still retained even at that temperature.View full abstractDownload PDF (1104K) -
Tetsuya Akiyama, Toshio Terasaki1988 Volume 52 Issue 8 Pages 792-796
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effects of grain size and temperature of solution heat treatment on the sensitization of austenitic stainless steel were investigated by normalizing the grain size effect, the measurement of the incubation period in the sensitization and the comparison of the behavior of the sensitization following the heat treatment at 1113 K for 700 s (or 2000 s) for two different grain size materials.
To measure the incubation periods, the electrochemical potentiokinetic reactivation (EPR) test and the 10% oxalic acid etch test were used.
The behavior of the sensitization following the heat treatment at 1113 K for 700 s (or 2000 s) was measured by the EPR test.
The higher temperature of the solution heat treatment, the longer was incubation period. When the reactivation ratio was normalized, the behavior of the sensitization following the heat treatment at 1113 K for 700 s was the same, even if the grain size and the temperature of the solution heat treatment were different.View full abstractDownload PDF (1349K) -
Shinji Itoh, Koichi Sato, Junji Takahashi, Haruno Okochi1988 Volume 52 Issue 8 Pages 797-802
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe fundamental parameter (FP) method for the analysis of seven analytes (Al, V, Cr, Fe, Zr, Mo and Sn) in titanium alloys was investigated. The program used for calculation was the XRF-11. One homogeneous multi-elements home-made standard was made by the plasma electron-beam melting method using several press compactions which were prepared from various metal powders and sponge titanium. The chemical composition of the standard was determined by the JIS and TIS analytical methods. The spectral line overlaps were examined. The net count rate of the unalloyed titanium at the VKα peak angle was measured and that at the TiKα peak angle and the ratio (mV,Ti) between them was found to be 0.0064. The net count rate of the Ti-V binary alloys containing no chromium at the CrKα peak angle was measured and that at the VKα peak angle. The ratio (mCr,V) between them was 0.0101. For the determination of chromium the count rate for VKα must first be corrected for interference from TiKβ and then CrKα count rate corrected for interference from VKβ. The relative standard deviations of repetitive six measurments for the analytical values of the seven analytes were in the range of 0.30-1.43%. The determined values for NBS SRMs and IMI CRMs titanium alloys by the FP method agreed well with those certified values.View full abstractDownload PDF (823K) -
Yuji Muramatsu, Kunio Funami, Kohmei Halada, Kenichi Hoshimoto1988 Volume 52 Issue 8 Pages 803-809
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMo-ZrO2 sintered materials were fabricated by the powder metallurgical process, and they were further densified by hot isostatic pressing (HIP) in order to improve their mechanical properties and reliability. The microstructure of HIP’ed materials was examined by an optical and transmission electron microscopes. Their mechanial properties were also examined with those of sintered materials.
The results were as follows:
(1) The addition of ZrO2 powder in molybdenum restrained the abnormal grain growth of molybdenum, and resulted in fine structure. Although residual pores were diminished, the structure was hardly influenced by the HIP-treatment used in this experiment.
(2) With the t→m transformation of ZrO2, strain and dislocation took place in the vicinity of the interface of molybdenum and ZrO2 particle. Nevertheless, microcrack could not be detected.
(3) Mechanical properties were effectively improved by HIP-treatment. Their improvement was dependent on ZrO2 content, and the bending strength and deflection increased markedly in the contents of 5.0-15.0 vol%, while the fracture toughness was much improved in less than 10.0 vol%.
(4) The reason why the HIP’ed materials have high ductility and toughness together with high strength is explained by the diminution of residual pores due to HIP and to toughness caused by the t→m transformation of ZrO2.View full abstractDownload PDF (2557K) -
Hitoshi Matsumoto, Ken-ichi Kondo, Akira Sawaoka1988 Volume 52 Issue 8 Pages 810-815
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSNiTi alloy powder with a relative density of 70% to the theoretical density was shock-consolidated by impacting at flyer velocities up to 1.7 kms−1 using a powder gun. The behavior of dynamic consolidation was investigated by hardness testing, microstructure observation of the recovered samples and calculation of the shock state. The powder samples shock-treated were densified with deformation and surface melting of particles. The volume of the melts increased with increasing impact velocity, and voids and cracks were generated in them. The powder sample is compressed up to 99% of full density at the optimum impact velocity of 1.3 kms−1. Effects of mechanical deformation, heating and rapid cooling during the shock treatment evidently appeared in the hardness and microstructure of the compacts.View full abstractDownload PDF (1827K) -
Kenki Hashimoto, Haruo Doi, Kazuo Kasahara, Tokuzou Tsujimoto, Tomoo S ...1988 Volume 52 Issue 8 Pages 816-825
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMicrostructures and crystal structures of Ti-34, -36 and -38 mass%Al alloys containing Mn, Nb, V or Zr up to 10 at% as a third element has been examined using a optical microscope, an electron probe microanalyzer and an X-ray diffractometer. The alloying effects have been discussed from the viewpoint of ductility improvements of the alloys.
Ternary phase diagrams around the TiAl phase have been determined. The structure is refined by the addition of each third element to the alloys. The Ti3Al phase is decreased and the annealing twins are increased by the addition of Mn or V. The microstructure is considered to be favourable for improving the ductility of the alloys.
The lattice parameter of the TiAl (γ) phase increases with increasing Zr or Nb content and decreases with increasing Mn or V content, as can be expected from the atomic size factors of the third elements. On the other hand, the axial ratio c⁄a of the γ phase decreases with increasing Mn, Nb or Zr content and remains at a fixed value for the addition of V. This alloying effect on the axial ratio can be explained from the condition in which the increase in strain energy with the lattice parameter is minimized. It is recognized that in the γ phase Zr and Nb are substitute for the Ti site, Mn for the Al site and V for both sites. Also, it can be estimated that the antiphase boundary energy of γ is decreased by the addition of Mn, V or Nb, and that the stacking fault energy of γ is decreased by the addition of Mn or V.
It is concluded that the third elements which improve the ductility of TiAl-based alloys are those which are smaller in atomic size than Ti and Al and replace the Al site to reduce the Al content in the γ phase.View full abstractDownload PDF (2736K) -
Akira Chiba, Kazuyuki Hokamoto, Minoru Nishida1988 Volume 52 Issue 8 Pages 826-833
Published: 1988
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe growth of the reaction layers at the wire-matrix interface in the annealing temperature range from 473 to 873 K and its influence on the strength of the composite using the uncoated wire and Ni-coated wire were examined.
When using an uncoated wire, the reaction layer was not formed at the wire-matrix interface below about 573 K, and began to form above 673 K. The reaction layer was composed of FeAl3 and Fe2Al5. When using Ni-coated wire composite, the reaction layer was not formed up to 573 K, like an uncoated wire. At temperature above 673 K, NiAl3 was formed at Ni-coated layer, while FeAl3 and Fe2Al5 were formed at the wire side. The effect of the annealing temperature on the tensile strength of the composite was investigated by annealing at various temperatures for 180 ks. The tensile strength of the uncoated wire composite by annealing decreased about 10 MPa compared with the as-welded one and showed a constant value at 473-673 K. Above 773 K, it decreased drastically. On the Ni-coated wire composite, the same tendency was observed and especially its strength showed a maximum value at 673 K. The high strength at 673 K was discussed on the basis of Cooper and Kelly’s analysis using the result of the transverse test on the single wire composite. In the uncoated fiber composite, the high strength at 673 K annealing was to come from the increasing bonding strength by the interdiffusion at the wire-matrix interface. The Ni-coated wire composite was strengthened not only by the interdiffusion but also by the formation of intermetallic compounds.View full abstractDownload PDF (2083K)
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