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Volume 51, Issue 9
Displaying 1-15 of 15 articles from this issue
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Isao Tanaka, Jin-ichi Takamura, Kozo Furukawa, Hirokazu Taniguchi, Hir ...1987 Volume 51 Issue 9 Pages 781-790
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSOn isochronal annealing of quenched-in resistivity in dilute Au-Sb alloys, very complicated annealing curves have been observed. This anomalous annealing behaviour is fully understood in terms of the consecutive motion of vacancy-solute (VS) pairs, owing to the strong binding between a vacancy and a solute atom, which leads to the successive formation and dissociation of multiple vacancy-solute complexes ViSj (i, j≥1) during isochronal annealing. Main results obtained are summarized as follows: (1) The substantial part of the isochronal annealing curve in the dilute Au-Sb alloy, as in the case of Au-Sn alloy previously reported, can be described in terms of the motion of VS pairs, except for stage X ranging from 453 to 573 K in which an anomalously large resistivity drop occurred. (2) The binding energy of VS pairs was determined to be 0.43±0.05 eV, on the basis of the analysis of the effective migration energy in stage δ3′ at which the dissociation of VS pairs is dominating. (3) From the analysis of the annealing kinetics in stage δ1, the migration energy of VS pairs was obtained as 0.59±0.02 eV, which is much smaller than the value of mono- or di-vacancies. (4) The frequency factor of the VS pair migration was found to be three orders of magnitude lower than that for mono-vacancy, which is due to the huge reduction in the frequency factor of the ω1 jump in terms of the five frequency jump model. (5) From the computer-simulation based on the reaction rate theory, during quenching and on subsequent annealing, the values of the binding energy, the resistivity contribution and the frequency factor of migration for various vacancy-solute complexes ViSj (i, j≥1) were determined.View full abstractDownload PDF (1621K) -
Takasi Takezawa, Katsuhiro Takebayashi1987 Volume 51 Issue 9 Pages 791-796
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of additional elements of Fe-80 at%Pd alloys on the formation of L12 type superlattice has been investigated by X-ray diffraction, transmission electron microscopy, and thermoelectric power and electrical resistivity measurements. FePd3 superlattice (L12 type) is found to form in the Fe-80 at%Pd alloy (A1 type) containing Mn, Al, In and Ga up to about 8 at%. Electron diffraction patterns of Fe-80 at%Pd alloys containing 4∼6.5 at%Al show superlattice reflections in addition to the fundamental reflections, and the dark field images by transmission electron microscopy exhibit the formation of ordered domain structures. The ordered domain size increases with increasing concentration of Al element. The order-disorder transition temperature, TC, is found on the curves of the thermoelectric power and electrical resistivity versus temperature of Fe-80 at%Pd alloys added Al element. The thermoelectric power and the electrical resistivity of these alloys increase with the form of FePd3 superlattice on ordering. Form these experimental results, the formation of FePd3 superlattice in the Fe-80 at%Pd alloys can be qualitatively explained by the Brillouin Zone effect.View full abstractDownload PDF (1244K) -
Hideki Hagi, Yasunori Hayashi1987 Volume 51 Issue 9 Pages 797-803
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFormation of hydride in the surface layer of nickel and Ni-(10, 30, 50 at%)Fe alloys cathodically charged with hydrogen has been investigated by means of X-ray analysis and transmission electron microscopy. It has been found that the nickel hydride, which is of the face-centered cubic structure with a lattice constant about 6% larger than that of nickel, is formed by dissolution of hydrogen into a nickel lattice, and plastic deformation is caused by the formation of the hydride. In Ni-(10, 30, 50 at%)Fe alloys, several kinds of hydride with fcc structure were formed in the surface layer. The hydrides in Ni-(0, 10, 30, 50 at%)Fe specimens were not stable in air at room temperature, and the lattice constants decreased as they decomposed gradually. Based on the concentration of hydrogen in the specimens calculated from the change in the lattice constant, the phase diagram of (Ni, Fe)-H system was obtained.View full abstractDownload PDF (2505K) -
Masuo Yamada, Teruto Kanadani, Akira Sakakibara, Mutsuo Ohta1987 Volume 51 Issue 9 Pages 804-809
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffect of pre-aging at 243 K or 273K on subsequent aging at 263 K (two-step aging) in Al-4 mass%Zn alloy was studied by measurements of electrical resistance and small-angle X-ray scattering (SAXS) intensity.
When pre-aging time (tApre) was relatively short (<600 s), the final value of the electrical resistivity (ρE) on the aging at 263 K was not affected by the pre-aging. As tApre became longer (>600 s), complicated behavior of ρE was observed according to the change of tApre at 243 K or 273 K.
In the case of pre-aging at 273 K the SAXS integrated intensity (q0) of thick specimens after the aging at 263 K decreased gradually from the value of not pre-aged specimens (q0263) with increasing tApre. On the thick specimen pre-aged at 243 K, except when tApre was very long, q0 was, within experimental error, not affected by the pre-aging, regardless of the complicated change of ρE.
Concerning thin specimen pre-aged at 243 K, in which annihilation of the vacancies at the surfaces could not be neglected, q0 after aging for long time at 263 K increased to q0263 of the thick specimens, exceeding q0 of the specimen aged at 263 K without pre-aging, as tApre was increased. For very long tApre q0 only reverted partially to a value larger than q0263.
The SAXS results have been discussed in terms of reduction in concentration of quenched-in vacancies during the pre-aging and of volume fraction of GP zone.
In spite that q0 that was attained on the pre-aging for not so long time at 243 K was fairly smaller than q0263, q0 reduced at the initial stages of subsequent aging at 263 K. It was considered that this reduction would suggest the dissolution of the small GP zones formed at 243 K, even though the solid solution was supersaturated.View full abstractDownload PDF (2083K) -
Mutsuo Ohta, Akira Sakakibara, Teruto Kanadani, Masuo Yamada1987 Volume 51 Issue 9 Pages 810-814
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHardnesses at various locations in the grain have been studied on an age-hardened Al-10 mass%Zn alloy during the softening brought about by the reversion treatment. Softening occurred at an earlier stage in the region near the specimen surface and in the region near the grain boundary than in the interior of the grain. It is considered that the action of the specimen surface as a source of vacancies increases the vacancy concentration in the region near the surface relative to the interior. Grain boundaries may be regarded as easy paths for vacancy migration, but it is uncertain whether they are sources of vacancies. With progressing reversion, the hardness in the interior of the grain also became smaller than that obtained before the reversion although it was higher than the hardness near the surface and near the grain boundary. Softening in the interior is considered to be caused by the residual vacancies remaining after aging and by the vacancies supplied by the interior sources such as dislocations. Earlier softening near the surface was observed also in an Al-3 mass%Cu alloy.View full abstractDownload PDF (739K) -
Masamichi Miki, Yoshikiyo Ogino, Yasushi Hiramatsu1987 Volume 51 Issue 9 Pages 815-823
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of B and Cr additions on the grain refinement, mechanical properties and martensitic tranformation temperature of a Cu-14 mass%Al-3 mass%Ni shape memory alloy were investigated by optical and scanning electron microscopy, tensile-testing, X-ray analysis and differential scanning calorimetory.
The addition of B or Cr was effective in grain refinement of cast alloy ingots. Equi-axed grains were observed only in the ingots added both B and Cr. The addition of B or Cr was also effective in grain refinement of a recrystalized β phase. The minimum β grain size obtained was 80 μm for the alloy containing 0.05%B and 0.1%Cr. Such precipitates as CrB2, CrB, Cr2B, and Cr rich phase were detected from the β alloys containing 0.05%B and 0.1%Cr, 0.05%B and 0.3%Cr, 0.05%B and 0.5%Cr, and 0.05%B and 0.8-1.0%Cr, respectively. It is probably that these fine precipitates play an important role in the suppression of β grains growth, resulting in the grain refining.
By the addition of B or Cr, the ductility of the Cu-14%Al-3%Ni alloy at 196-1073 K was improved. That is, grain boundary cracking was remarkably suppressed and fracture mode changed from brittle fracture to ductile one. The Ms temperature was decreased by the addition of B or Cr. But the excess addition of Cr (>0.1%) makes an increasing in Ms temperature.View full abstractDownload PDF (3264K) -
Masamichi Miki, Yoshikiyo Ogino1987 Volume 51 Issue 9 Pages 824-829
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of Cr and B additions on the ductility of a Cu-14 mass%Al-3 mass%Ni shape memory alloys at 973 K in a (β+γ2) two-phase region were investigated by tensile-testing and optical microscopy.
Tensile-specimens were prepared from the alloy sheets hot-rolled at 973 K. The grain size and volume fraction of β and γ2 phases in the specimens were controlled by the hotrolling and additions of Cr and B. The additions of these elements promoted the grain refinement of β and γ2 phases and the equalizing of the volume fraction of these phases. The minimum γ2 grain size, 6 μm, and the maximum γ2 volume fraction, 0.45, were obtained in the case of 0.05%B and 0.1%Cr additions.
As the result, on tensile-testing at 973 K, the specimens containing Cr and B were deformed superplastically without necking, while the non-added specimen was fractured by necking. The maximum elongation values obtained were 73% for the non-added alloy, 132% for the 0.5%Cr alloy, and 173% for the 0.05%B and 0.1%Cr alloy. The maximum values of the strain rate sensitivity index (m) were 0.2 for the non-added alloy, 0.35 for the 0.5%Cr alloy, and 0.4 for the 0.05%B and 0.1%Cr alloys.View full abstractDownload PDF (1803K) -
Masami Fujiwara, Tomoo Hirokawa1987 Volume 51 Issue 9 Pages 830-838
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe strength of obstacles impeding the motion of dislocations has been studied using an etch hillock technique. Plate tin single crystals (99.999 mass% purity) were stretched in the [110] direction by a creep-testing apparatus. When applied shear stresses on the [100](010) slip system were more than 55 kPa, all the primary dislocations moved and most of them were stopped by main obstacles. Some of the stopped dislocations passed through the obstacles by a thermally activated process, while others kept on stopping until etching was finished. The passage rate γ of dislocations through the obstacles was obtained by discriminating the shapes of hillock traces on 35 crystals under stress from 40 to 225 kPa. The values of γ did not increase monotonically but with three steps at 55∼80 kPa, 115∼140 kPa and 175∼210 kPa as stress was elevated. This finding shows that the distribution of the strength of main obstacles was not uniform but has three peaks. Such a phenomenon cannot be explained by the long-range elastic interaction with other dislocations but by the intersection with forest dislocations. The resistance to the motion of dislocations was computed on all kinds of forest dislocations which it was possible to intersect. The critical stresses for passing through forest dislocations were found to separate into three groups according to their slip system. As a result, the stress dependence of γ in this experiment was clearly understood by considering the resistance due to the intersection with forest dislocations.View full abstractDownload PDF (2024K) -
Yuji Ikeda, Masahiro Tosa, Takashi Kimura, Kazuhiro Yoshihara, Kazuyos ...1987 Volume 51 Issue 9 Pages 839-847
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt was previously reported that the adherence of alumina to type 321 stainless steel is strengthened by TiC precipitation at the alumina/steel interface. The purpose of this work is to improve the oxidation resistance of alumina-coated steels by taking advantage of this strengthening effect. The surface precipitation behavior was measured on 5 kinds of Fe-C-Ti alloys by means of AES, and the high temperature oxidation test was carried out on these alloys coated with alumina.
These alloys are classified into three types: The first is the alloys with an atomic ratio of Ti/C>1 (Fe-0.02C-0.7Ti, Fe-0.14C-0.7Ti). These two alloys show the precipitation of TiC, no precipitation of graphite and a slight segregation of S at the surfaces. When they are coated with alumina the oxidation resistance is very high and the enrichment of Ti is found at the alumina/alloy interface. The second is the alloy with an atomic ratio of Ti/C∼1 (Fe-0.19C-0.7Ti). This alloy has little precipitation of TiC, no precipitation of graphite and a little segregation of S at the surface. When it is coated with alumina the oxidation resistance is inferior to the alloys of the first type and the interfacial enrichment of Ti is not found. The third is the alloys with an atomic ratio of Ti/C<1 (Fe-0.47C-0.7Ti, Fe-0.26C-0.1Ti). They do not show any TiC precipitation, but a substantial amount of graphite precipitation or S segregation at the surfaces. When they are coated with alumina the oxidation resistance is the lowest and graphite, instead of Ti, precipitates at the alumina/alloy interface. This graphite precipitation causes undulations of the alumina layer. It is concluded that the role of Ti in the alloys with an atomic ratio of Ti/C>1 is to act as an adhesive at the alumina/alloy interface, to suppress the interfacial segregation of S which can cause the weakening of alumina-alloy bond and to prevent the interfacial precipitation of graphite which can break the alumina coating layer.View full abstractDownload PDF (2252K) -
Electromotive Force of the Hydrogen Concentration Cell based on SrCe0.95Yb0.05O3−δ Solid ElectrolyteNorihiko Fukatsu, Kouichi Yamashita, Teruo Ohashi, Hiroyasu Iwahara1987 Volume 51 Issue 9 Pages 848-857
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo clarify the conduction mechanism of a new type proton conductive solid electrolyte SrCe0.95Yb0.05O3−δ, emf’s of a gas concentration cell based on this material were measured for various electrode potentials in the temperature range 973-1373 K. It was found that the emf is settled at a unique value only when both the oxygen and the hydrogen potentials of the electrodes were specified. The model of the conduction mechanism to restrict the charge carriers to only interstitial proton and positive hall could not account for all the observed potential dependances of emf values. From the results on the cells operated as an oxygen concentration cell, it is strongly suggested that oxygen vacancy acts as one of the charge carriers of this electrolyte.View full abstractDownload PDF (925K) -
Seigi Aoyama, Mituaki Onuki, Yasuhiko Miyake, Ryoichi Urao1987 Volume 51 Issue 9 Pages 858-863
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe softening characteristics of cold-drawn pure copper wires were studied in relation to hot-working processes and impurities of hot worked Cu wire rods. The characteristics of several kinds of hot-rolled wire rods were examined by means of structural observations, tensile tests and electrical resistivity measurements. The softening characteristics of cold-drawn copper wires were obtained from spring elongation tests and electrical resistivity measurements of 90% cold-drawn wires.
It was found that the grain size and Cu2O particle size of the continuous casting and rolling rod (SCR: Southwire Continuous Rod) were the smallest and its Cu2O particle distribution was uniform. On the other hand, the grain size of Oxygen Free Copper (OFC) wire rod was the largest and its electrical conductivity was the highest. SCR cold-drawn copper had the lowest softening temperature. Specimens of copper wires could be arranged according to the order of softening tendencies by annealing:
\ oindentSCR>TPC 1(normal Tough Pitch Copper)>OFC>TPC 3(Tough Pitch Copper with 16 ppm Pb and 11 ppm Sn).
\ oindentA large amount of annealing twins was observed in the SCR wires.
From these experimental results, the softening characteristics of the cold-drawn copper wires are considered to be related to metallurgical structure which depends on the hot-working processes and purities.View full abstractDownload PDF (1862K) -
Than Trong Long, Tatsuyoshi Aisaka, Michihiro Ose, Mikio Morita1987 Volume 51 Issue 9 Pages 864-870
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe tensile properties and wear resistance of SiC whisker reinforced aluminium alloy 4032 composites were investigated.
The elastic modulus of T 6 heat treated SiC/4032 composites can be expressed as
(This article is not displayable. Please see full text pdf.)
The wear loss of SiC/4032 composites decreases rapidly with an increase in the volume fraction of SiC whisker up to 14%, beyond which it remains unchanged.
The addition of BN gives rise to the degradation of the mechanical properties and also gives rise to the degradation of the coefficient of friction which improves the wear resistance of the composites.
The wear resistance of SiC/4032 composites depends remarkably on the size and distribution of Si particles of aluminium alloy 4032 matrix.View full abstractDownload PDF (1702K) -
Muneyuki Amano, Michio Shibata, Yasuo Sasaki1987 Volume 51 Issue 9 Pages 871-878
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effects of powder size, keeping environment and keeping time on the first hydriding process of FeTi1.15O0.014, FeTi1.14O0.023 and FeTi1.15O0.024 were investigated by means of a volumetric method and differential scanning calorimetry. The change in amount of hydrogen storage of the alloys during hydriding-dehydriding cycles was also investigated by obtaining pressure-composition isotherms and by means of X-ray analysis. It was found that the alloy powder greater than a few ten meshes showed a good activity against hydrogen even after keeping in distilled water for 22 months. With increasing hydriding-dehydriding cycles at 313 K the formation of γ hydride became difficult and the broadening of X-ray diffraction lines associated with the FeTi phase was observed. The hydrogen absorption rate of the oxide phase at 313 K was much slower than that of the FeTi phase, and the hydrogen desorption from the hydrogenated oxide phase was not observed at room temperature. It is concluded that a mechanism of hydrogen penetration through the phase boundaries plays an important role for the first time hydriding of the alloys. The difficulty of the γ hydride formation with increasing hydriding-dehydriding cycles can be explained in terms of hardening due to the high density of dislocations generated during the cycles.View full abstractDownload PDF (1108K) -
Yuko lnatomi, Kazuo Terashima, Hideki Matsuoka, Ryoichi Yamamoto, Masa ...1987 Volume 51 Issue 9 Pages 879-880
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (276K) -
Moritaka Hida, Eiichi Sukedai1987 Volume 51 Issue 9 Pages 881-882
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (318K)
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