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Volume 38, Issue 4
Displaying 1-15 of 15 articles from this issue
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Hisashi Suzuki, Motohiro Kanno, Kazuyoshi Fukunaga1974 Volume 38 Issue 4 Pages 287-293
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt is well known that a small addition of Sn to Al-Cu binary alloy sharply suppresses the aging rate at low temperatures and accelerates the aging rate at high temperatures (about 100 to 200°C). The mechanism of the former phenomenon has been already studied by the present authors, with the result that the suppression would be caused by the decrease of solid-solubility of Cu in α-phase at solution temperatures due to the Sn addition. In the present work the mechanism of the latter was investigated.
Two kinds of alloy systems of 3 and 4 wt% Cu containing 0 to 0.25 wt% Sn were prepared. Aging behaviors and aged structures of specimens at high temperatures were studied in detail by hardness, calorimetric, electric resistivity measurements and transmission electron microscopy, respectively.
The results obtained were as follows:
(1) The aging process of the Sn-containing alloys was found to be accelerated and the peak hardness values increased with increasing amount of Sn dissolved in α-phase. The three-phase alloys at solution temperatures showed naturally the same aging behaviors. However, a slight difference in hardenability was observed between the two alloy systems having the same amount of Sn dissolved in α-phase, which should be further studied.
(2) The results of various measurements can be explained on the basis of the transmission electron micrographs of the aged structures. For example, the θ′ precipitate in the Sn-containing alloys became finer and densely distributed with increasing amount of Sn dissolved.
(3) A small spot (∼30 Åφ) with a dark contrast was found to adhere to a corner of θ′-phase (when θ′-phase was coarsened after prolonged aging), and that the numbers of the spot or the numbers of θ′-phase increased with increasing amount of Sn dissolved. Simple caluculation of the amount of the spot showed that it would be the Sn-rich phase precipitated at the very early stage of aging.
(4) Therefore, the aging acceleration in the Sn-containing alloys was considered to be due to the effect of the Sn rich phase acting as nucleation site of the θ′ precipitate.View full abstractDownload PDF (1104K) -
Isao Itoh, Mitsuru Togashi, Takeo Hikage1974 Volume 38 Issue 4 Pages 294-300
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe dezincification rate of β-brass in vacuum has been measured by the thermobalance method over a temperature range 500 to 800°C. The effects of Ag, Mg, Al, Mn, Si, Ge, Sn and Ni as alloying elements was also studied. The results were discussed in comparison with the case of α-brass reported previously. Results are summarized as follows:
(1) The dezincification rate of β-brass obeyed the parabolic rate law as was expected from the diffusion-controlled mechanism, while in the case of α-brass with 30 wt% Zn the amount of weight-loss was proportional to time.
(2) The dezincified β-brass layer consisted of two parts observed in α-brass with 30 wt% Zn, one of them near the specimen surface was more porous.
(3) Additions of Si, Ge, Sn and Al increased the rate of dezincification, while no effect was observed by additions of Ag, Mg, Mn and Ni. The effect of each alloying element on the dezincification rate of β-brass was smaller than that observed in α-brass.View full abstractDownload PDF (884K) -
Kenji Okazaki, Koji Tanoue, Hans Conrad1974 Volume 38 Issue 4 Pages 300-309
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSingle strain rate cycling tests were performed for commercial Ti-4Al, Ti-5Al-2.5Sn, Ti-6Al-4V and Ti-5Al-2Cr-1Fe alloys over the temperature range of 77 to 700°K. The effects of grain size and strain on the parameter m which was obtained directly from the tests were eliminated by employing the double extrapolation technique to yield ma*. ma* thus obtained for substitutional alloys still includes the effect of substitutional solute atoms on the athermal component as given by (ma*⁄β=σ*+σμ(Cs), so that the thermal component in substitutional alloys cannot be obtained simply by double extrapolations of m as in alpha titanium which contains only interstitial solute atoms. However, a comparison of the data for alpha titanium which contains no substitituional solute atom but the same interstitial solute content as the present Ti-4Al with those for Ti-4Al led to the conclusion that substitutional solute atoms do not influence the temperature dependence of the athermal component in the temperature range studied. σμ(Cs) was then determined at the temperature T0 where the (ma*⁄β)−T curve exhibited the inflection point. The thermal component in substitutional alloy σ*(ma*) which was estimated by subtracting [σμ(Cs)]T0 from (ma*⁄β) was in good accord with that estimated by using the conventional back extrapolation technique, and it is concluded that the double extrapolation technique can be applicable even to substitutional alloys whose temperature dependence of Young’s moduli is not known.View full abstractDownload PDF (687K) -
Ishi Miura, Tsuyoshi Nakano1974 Volume 38 Issue 4 Pages 310-316
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDendrite structures have been studied from the standpoint of solidification theory. In this paper, they were treated from the standpoint of pattern recognition. Multivariate analysis was applied to the dendrite structures; length (L), width (M) and spacing (N) of the stalks and length (l), width (m) and spacing (n) of the arms were measured as variables, and then solidification rate (R), content of added element (C) and temperature gradient (G) at the solid-liquid interface were obtained.
Experiments were done on Ag-Pd alloys (investment casting) or Al-Cu alloys and Ag-Sn alloys (unidirectional solidification) and 10∼100 measurements were made on each specimen.
The analysis of the variance and of the correlation coefficient were done to determine these many variables as statistical problems. The results obtained are as follows: l is significant for C and has no significance to R in unidirectional solidification. M is not significant to C but significant to R in the investment casting. This means that R plays an important role in the pattern. The problems concerning the correlation matrix are as follows: M and m have a strong correlation, and the correlation between m and n suggests a relation to the distribution of solutes. N shows a strong independency. These correlationships are tabulated.View full abstractDownload PDF (698K) -
Junji Shibata, Tadashi Horiuchi, Shigeki Iyoki, Sanji Nishimura1974 Volume 38 Issue 4 Pages 316-322
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt was clarified in this paper that the extraction of Cu(II), Co(II) and Ni(II) ions with di-(2-ethyl hexyl) phosphoric acid is not affected by ammonium ion, while the extraction with Versatic Acid 911 is considerably hindered. Theoretical treatment on the solvent extraction in the presence of ammonium ion was developed to predict the extent of hindrance to the extraction by the formation of metal ammine complexes in the aqueous phase. The experimental results are in fairly good accodance with the theoretical values.View full abstractDownload PDF (600K) -
Junji Shibata, Sanji Nishimura1974 Volume 38 Issue 4 Pages 323-327
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt is well known that the maximum extraction of metal by carboxylic acids is obtained at pH values just below the hydroxide precipitation.
However, pH values of metal extraction in the presence of sulphate and chloride ions differ from the values described above.
In this paper, the distribution of the metal ion was studied at a constant total ionic strength using sulphate or chloride as the supporting electrolyte anion.
The ion association constants for the association between the ligand and the metal ion were computed from those experimental data.View full abstractDownload PDF (397K) -
Kazuaki Fukamichi, Norio Fukuda, Hideo Saito1974 Volume 38 Issue 4 Pages 327-331
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSInvar and Elinvar alloys are important materials for precision instruments. But, practical applications of these alloys are often restricted because of their ferromagnetism. Therefore, researches to develop nonferromagnetic Invar or Elinvar alloys have recently received considerable attention.
Chromium is an antiferromagnetic metal and its physical properties around the Néel temperature are drastically affected by the addition of solute atoms. We have investigated the thermal expansivity Δl⁄l, the electical resistivity Δρ⁄ρ and the temperature dependence of magnetic susceptibility χ for Cr-Co dilute alloys. The thermal expansivity of these alloys in the vicinity of room temperature is very small, showing the Invar characteristics. Some alloys show also the Elinvar characteristics in the same temperature range where the Invar characteristics occur. It is for the first time that both Invar and Elinvar characteristics have been found in chromium dilute binary alloys. The magnetic susceptibility of these alloys is less than 5×10−6 emu/g, indicating that these alloys are practically nonferromagnetic.
In these alloys the Néel temperature varies irregularly with increasing cobalt concentration; it decreases slightly for cobalt concentrations up to 2.0%Co, increases up to 2.5%Co, and decreases with further increase in cobalt concentration. But the Néel temperature determined from the temperature dependence of Δρ⁄ρ and χ does not coincide with an inflection point on the thermal expansivity curve.View full abstractDownload PDF (423K) -
Iwao Katayama, Shigeo Igi, Zensaku Kozuka1974 Volume 38 Issue 4 Pages 332-338
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSE.M.F. of a galvanic cell with the solid electrolyte (ZrO2+CaO) was measured to determine the activities of gallium in the temperature range of 800∼1000°C and the composition range of 5∼58 at%Ga for solid Ni-Ga alloys, and thermodynamic functions were derived from the results. The cells used were as follows:
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Activites of both components showed large negative deviations from Raoult’s law; Activity changes with composition in nickel-rich α-solid solution and in the α′(Ni3Ga)-phase were small, but very large in the β(NiGa)-phase. Relative integral molar free energies of formation showed minimum values at the stoichiometric composition NiGa. Intergral enthalpies and entropies of formation showed relatively large negative values.View full abstractDownload PDF (528K) -
Kojiro Kobayashi, Hideo Shingu, Ryohei Ozaki1974 Volume 38 Issue 4 Pages 338-345
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCrystallographic orientation relationships between primary silicon and aluminum halo crystals in hyper-eutectic Al-Si alloys have been studied by micro-focus X-ray diffraction analysis.
The apparently random orientation relationships have been classified into simple relationships when the twinnings in silicon crystals are taken into consideration. These relationships are;
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\ oindentfor untreated alloys and,
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\ oindentfor sodium treated alloys.
The occurrence of relationships (1) for untreated alloys and (4) for sodium treated alloys are most frequent and it has been calculated that the relationships (2) and (3) are within 13.8° inclination from (1) and the relationships (5) and (6) are within 11.4° inclination from (4).
The crystallographic relationships between silicon and aluminum for untreated and sodium treated alloys, when represented by (1) and (4) respectively, can be matched by a 54.7° rotation around the [001] axis of aluminum crystals.View full abstractDownload PDF (826K) -
Toshio Shimoo, Akira Harada, Hiroshi Kimura, Masao Kawai1974 Volume 38 Issue 4 Pages 345-352
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCaO-Al2O3 binary slag and carbon saturated iron were melted in a graphite crucible and then reacted with nitrogen. In this experimental condition, complicated reactions took place electrochemically among gas, slag, metal and graphite. This study was made to determine the behavior of anions as nitride (N3−), cyanide (CN−) and carbide (C22−) in slag and N and Al in metal.
(1) Within a short reaction time (60 min), the rate of absorption of N3− and CN− in slag can be given by d(N)⁄dt=k′.
(2) The temperature dependence of absorption of nitrogen in slag melted with metal is larger than without metal.
(3) As the content of alumina in slag increases, the rate of absorption of nitrogen in slag is reduced but the rate of transfer of nitrogen from slag to metal increases.
(4) With increasing initial content of Al in metal, the transfer of nitrogen from slag to metal slows down while the absorption of nitrogen in slag is accelerated.
(5) As the reaction proceeds over a long time (10 hr), the components in slag and metal show a complicated behavior which can be divided into three stages in some cases.
(6) These results can be qualitatively explained by the electrochemical theory.View full abstractDownload PDF (650K) -
Yuichi Tanaka, Katsuya Ikawa1974 Volume 38 Issue 4 Pages 352-357
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe influence of concurrent phase transformation on the deformation of ductile cast iron was studied under tensile stresses of 300 to 1300 g/mm2 at high heating and cooling rate (225°C/min). It is shown that the strain rate sensitivity exponent, m, is 0.8 and the transformation strain is greater on heating from pearlite to austenite than on cooling from austenite to pearlite. This tendency is similar to that at low heating and cooling rate (5°C/min). The transformation strain at the high heating and cooling rate results in a smaller transformation strain. It is suggested that the plasticity is due to creep enhanced by excess vacancies generated during the volume change. Large uniform elongations (above 200 per-cent) can be obtained by repeated thermal cycling under constant load. In the early thermal cycling, the voids are formed by the pearlite\ ightleftharpoonsaustenite transformation straining at both sides of spheroidal graphite. In the later stage, the voids are filled up by the matrix structure successively.View full abstractDownload PDF (731K) -
Masaru Okuyama, Shiro Haruyama1974 Volume 38 Issue 4 Pages 358-365
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe film thickness, the immersion potential, and the hydrogen evolution reaction on the passivated Fe-Ni alloys were investigated in a borate buffer solution at pH 8.39. The results are discussed in connection with a previous paper in which the composition and structure of passive films were studied by means of coulometry and colorimetric analysis. The following conclusions are obtained:
(1) The exchange current density and the Tafel slope of the hydrogen evolution reaction on the passivated Fe-Ni alloys decrease with increasing Ni content and show abrupt changes at 30 wt%Ni. This is probably due to Ni3O4 which remains unreduced on the surface during the cathodic process. (2) The immersion potential of the passivated Fe-Ni alloys is likely to be related with the activity of γ-Fe2O3 in the outer layer of passive films. (3) There is a hyperbolic relation between film thickness and Ni content in the alloys. This can be explained by assuming that the passive films consist of a fine mixture of Ni and Fe oxides. (4) The corrosion resistivity of the alloys is related with the excess oxygen concentration in the outer layer of the passive films.View full abstractDownload PDF (737K) -
Tadashi Maki, Sadamasa Shimooka, Shigeru Fujiwara, Imao Tamura1974 Volume 38 Issue 4 Pages 366-371
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe authors have previously found that the morphology of martensite in Fe-Ni-0.25%C alloys changes at about −150°C from a lenticular to a thin plate with decrease in Ms temperature. In this investigation, the relation between the transition temperature from the lenticular to the thin plate and the carbon content has been examined by using several Fe-Ni-C alloys with about 0 to 0.9%C and 25 to 35%Ni. Furthermore, the transformation characteristics of the thin plate martensite have been observed as compared with those of the lenticular martensite. The results obtained are as follows.
(1) The transition temperature at which the morphology of martensite changes from a lenticular to a thin plate rises with increase in carbon content. In carbon-free Fe-Ni alloys, the lenticular martensite is formed even at −196°C. In Fe-Ni-C alloy, for example, containing about 0.8%C, the thin plate martensite is formed at temperatures below about −100°C.
(2) The following characteristics of transformation behavior have been observed in thin plate martensite. (a) With decrease in cooling temperature, martensite plates thicken in addition to subsequent formation of new martensite plates. (b) The burst phenomenon is not observed. (c) Accommodation slip in martensitic transformation is not observed in the surrounding austenite which is adjacent to the martensite. These characteristics are entirely different from usual lenticular martensite.View full abstractDownload PDF (902K) -
Sakae Kimura, Rikuro Otsuka1974 Volume 38 Issue 4 Pages 371-376
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt is well known that the protective film on beryllium bronze consists of beryllium oxide BeO. In the present study this was confirmed by means of TSEE (thermally stimulated exoelectron emission). The surface of beryllium bronze oxidized and irradiated with γ-ray gave glow curves identical with those of beryllium oxide having the characteristic emission peak at 230°C. The pattern of glow curves for specimens treated in the same manner was identical, but the height of the glow peaks varied with specimens. It was also found that the emission for the same specimen decreased as the irradiation and measurement of the emission were repeated. In order to improve the reproducibility of the emission, the specimens were aged in vacuum. They were examined in the same way as described above. The aging effect did not always exert favourable influences upon the reproducibility.View full abstractDownload PDF (454K) -
Toru Miyazaki, Hiroshi Murayama1974 Volume 38 Issue 4 Pages 377
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (258K)
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