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Volume 28, Issue 6
Displaying 1-12 of 12 articles from this issue
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Takashi Kimura, Haruki Hisamatsu1964 Volume 28 Issue 6 Pages 293-297
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSElectrical resistivity measurements have been carried out to clarify the early stage of sintering of metal compacts. The effects of compacting pressure and sintering atmosphere on the change in electrical resistivity at a continuously raising temperature were investigated with copper and nickel powder compacts.
With increasing the compacting pressure, the electrical resistivity of powder compacts was lowered, but the tendency of temperature-resistivity curves was little affected. It is concluded that the effect of compacting pressure on the early stage of sintering was not essential.
A conspicuous effect of sintering atmosphere on the change of electrical resistivity in heating was observed. In hydrogen, two steps of marked decrease of electrical resistivity appeared in the temperature-resistivity curves. The reason is considered that one appearing below 100°C is caused by the change in the surface condition of powders, that is, the desorption of trapped gases or adsorption of hydrogen gas and the reduction of oxide by hydrogen, and the other is caused by the adhesion of powders. On the other hand, in vacuo and in argon, only one maximum was observed in the temperature-resistivity curves, according to the adhesion of powders followed by the continuous desorption of trapped gases. In all cases a remarkable decrease of electrical resistivity occurred below the so-called sintering temperature where the compacts show the shrinkage.View full abstractDownload PDF (1230K) -
Naokatsu Tsuda1964 Volume 28 Issue 6 Pages 298-303
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSLead recrystallizes at room temperature. Therefore lead cable sheath, when subjected to various bending strains in the course of its manufacture, often develops very large grains as its grains grow with recrystallization. The large grain size is not desirable for the lead sheath because of its unfavourable effect on the fatigue resistance. Moreover, bending strains some times cause a non-uniform structure of the sheath.
In studying the grain growth of lead test pieces of 6.6×6.6 mm extruded square lead rods (99.98%) of different grain sizes were given 2%, 4%, and 6% bending strains at the bending temperature of 0°C or 30°C, and then heated for one hour at 100°C. Looking into the progress of the grain growth, it was the relationship between grain size before bending and grain growth rate was clarified, and an overall grain growth and a zoned structure in relation with bending strains was examined.
The conclusion obtained from the above was as follows:
(1) In case of the 0°C bending temperature, test pieces which were given 4% bending strain showed a large grain growth rate; the larger the original grain size, the smaller the rate. Under these strains, small-grain-size test pieces developed a zoned structure.
(2) In case of the 30°C bending temperature, the test pieces given 2% bending strain had the largest grain growth rate. Those of small original grain size developed an overall grain growth first and then a zoned structure.View full abstractDownload PDF (1547K) -
Kaizo Monma, Hajime Suto, Hiroshi Oikawa1964 Volume 28 Issue 6 Pages 304-307
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTensile creep properties of nickel-tungsten alloys containing up to about 10 at% of tungsten have been studied. Tests were carried out in argon atmosphere over the temperature range from 750° to 1200°C, and the stress range from 1.4 to 9 kg/mm2. Steady state creep rate (\dotεs) decreases with the increasing tungsten content. Temperature and stress dependences of steady state creep rate were analysed using Dorn’s equation, \dotεs=Cσnexp(−Qs⁄RT). Activation energies (Qs) are independent of applied stresses. They increase with the tungsten content from 66 kcal/mol for pure nickel to the maximum value of 84 kcal/mol for the alloy of 5 at%-tungsten, before they decrease with further increase of the tungsten content. Stress exponents (n) increase extremely with the tungsten content from a value of 5.0 for pure nickel to the maximum value of 7.2 for the alloy of 1.7 at%-tungsten. Whereas, in alloys containing more than this concentration of tungsten they decrease with the increasing content of tungsten to values less than that for pure nickel.View full abstractDownload PDF (868K) -
Kaizo Monma, Hajime Suto, Hiroshi Oikawa1964 Volume 28 Issue 6 Pages 308-312
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSComparison between steady state creep characteristics at high temperatures and lattice-diffusion characteristics of components has been made on nickel-copper, nickel-chromium, and nickel-tungsten alloys using the data reported previously by the present authors. It is found that : (1) The activation energy for the steady state creep (Qs) is close to that for the lattice self-diffusion (QD) of component in the alloys. In nickel-copper alloy, especially, Qs are almost equal to QD of copper atom which diffuses more rapidly than nickel atom in the alloys. Whereas, in nickel-tungsten alloys, it appears that Qs comes to be strongly related to QD of tungsten atom (slower diffusant) as the tungsten content increases. (2) According to the analysis of Weertman, changes in Qs and in stress exponent (n) show that the rate controlling process in the steady state creep is the climbing motion of dislocations in nickel-copper and nickel-chromium systems, as in the case of pure metals. In the nickel-tungsten system, however, the process seems to be altered as the tungsten content increases. (3) When the steady state creep rates (\dotεs) are related to the diffusion coefficients of vacancies (DV) and the applied stresses (σ) by \dotεs=C′σnDV, C′ is found to be independent of temperatures (and of applied stresses too) and to decrease always with increasing solute contents, even in the alloys of similar grain size.View full abstractDownload PDF (975K) -
Y\={u}ki Shirakawa, Daiji Amemiya, Takeshi Abe1964 Volume 28 Issue 6 Pages 313-319
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn Alnico permanent magnet has hitherto been heated at above 1250°C, which is in the range of the solid solution of the alloy, in order to obtain the best characteristics. From various investigations, we have found that the same or even better properties of the alloy can be obtained by the low temperature treatment at 875°C, lower than 1250°C. Conditions of the low temperature treatment are as follow the heating temperature is 875°C, the holding time at 875°C is 1 hr, the cooling velocity from 875°C to 750°C is about 1°C/sec, and the temperature range effective to magnetic cooling is to 800°C. The structure of the alloy affected by the low temperature treatment contains a dendrite which does not appear in the alloy heated at the high temperature and can be revealed by the etching with 30% HNO3.View full abstractDownload PDF (1772K) -
Mitsuru Idohara, Nakaaki Oda1964 Volume 28 Issue 6 Pages 320-324
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSOne would meet some difficulties in the application of spectrochemical method for such samples as those which are complicated in chemical form, very little in quantities or very complex in compositions. For analysis of the sample of analytical difficulties as described above, a spectrographic method in general use was studied, with which the major elements and impurities can be simultaneously determined under a fixed analytical condition and a set of standards. Factors investigated in the experiment were buffer, internal standard, and analytical conditions, and also experiments were carried out to find the effects of various chemical forms of samples on the analytical results. As a result, a method suited for routine industrial applications was established and has been used in the authors’ laboratory since 1959. The outline of the method is as follows; One part of a sample (>ca.1 mg) is mixed with ten parts of an internal standard-buffer (C+Na2CO3+BeO=1+1+0.01), packed into a cup of electrode (3 mm in dia, and 1 mm in depth), arced in a d.c. arc (10 ampere, 60 sec) and analysed by using Be as an internal standard element. By the method, various components at the range of 0.05∼100% in a sample of organic, inorganic or metallic state, can be rapidly determined, regardless of the chemical form of the component and of various matrices. Especially the method could be applied suitably to analysis of ores and nonmetallic inclusions in metals.View full abstractDownload PDF (1304K) -
Seita Sakui, Tsutomu Mori, Tsutomu Kakuma1964 Volume 28 Issue 6 Pages 325-329
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBy performing the dynamic tensile test and the static test at −196°C to 130°C, the temperature and the strain rate dependences of the lower yield stress of aluminum-magnesium alloys (0.93, 1.82 and 3.67%Mg) were studied with special attention to its grain size dependence following the Cottrell-Petch equation, σy=σi+kyd−1⁄2. The experimental results are as follows; the yield stress in the dynamic test was larger than that in the static test and the temperature dependence of the yield stress in the dynamic test was considerable, while in the static test it was negligibly small. The temperature dependence in the dynamic test and the strain rate dependence were due to the facts that for the lowest magnesium alloy, ky, the locking term according to Cottrell, had the temperature and the strain rate dependences and that for the higher magnesium alloys, σi, the frictional stress, had mainly such dependences. The above results were discussed from the viewpoint of the rate theory for unpinning of locked dislocations and dislocation movement in the lattice with precipitates or solute clusters.View full abstractDownload PDF (1667K) -
Kazuo Ota1964 Volume 28 Issue 6 Pages 330-334
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAcetylacetone-chloroform extraction involving the use of ethylenediamine-tetraacetate as a masking agent for foreign metals has been applied to the determination of beryllium in a high manganese zinc alloy, and the rapid spectrophotometric method is established with good accuracy and reproducibility in the range of 0.002 to 1.0% of beryllium.
Some factors affecting the absorbance are investigated. Suitable pH for extraction is 7.2 to 9.4, and its adjustment is simplified by using phenol red indicator.
The stabilized period of absorbance of the extracted acetylacetonate phase varies with the coexisting time of aqueous and organic phases after extraction. Maximum stability is obtained at the coexisting time 5 to 10 minutes, but the absorbance measured in 5 minutes gives a correct result even without the coexisting time.
As the salting-out agent any of NaCl, Na2SO4 or NaNO3 is successfully used.View full abstractDownload PDF (787K) -
Sennosuke Takahashi, Keiichi Iida, Masao Adachi1964 Volume 28 Issue 6 Pages 334-340
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn Nickel-Alumina dispersion strengthened alloys produced by hot extrusion, [100] fiber texture are formed to the extrusion direction.
With the increase of the alumina content in nickel, the fiber texture of the extruded specimens becomes more stable at high temperature annealing.
Creep resistance at a high temperature was controlled by the stable structure due to dispersion strengthening and by the stored energy during the working process of alloys, and the extruded specimens improved by cold work showed more strength. Dependence of the steady state creep rate on stress at 800°C was influenced by the dispersion state of particles and by working, and then the steady-state creep rate for some specimens was proportionate to about 12 power of stress.View full abstractDownload PDF (2725K) -
Masazô Okamoto, Ômi Miyakawa, Tamihiko Aihara, Takurô ...1964 Volume 28 Issue 6 Pages 341-348
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to determine the austenite grain size of steels continuously with the high temperature microscope, the observations on the austenite grain growth of 0.2%C steels (Si-Mn killed, or Al killed) in various atmospheres were carried out. The results obtained were as follows:
(1) When 0.2%C steels were heated in 3×10−5 mmHg vacuum, the austenite grains on the specimen surface were coarsened remarkably to A.S.T.M. No. 2 at 950°C, and its grain size was markedly different from that in the inner zone.
(2) If these steels were heated in extremely pure argon atmosphere in the pressure range of 0.6∼1.0 atm., the austenite grains on the specimen surface persisted in a grain size of A.S.T.M. No. 8 untill about 1150°C, and then they were coarsened. Their value of grain size was nealy equal to that of inner grains of the specimen.
(3) According to the electron microscopic study, it was observed that in high vacuum atmosphere the degree of oxidation on the specimen surface was less than that in argon. From this it was considered that the mechanisms for appearance of austenite grain boundaries in these atmospheres were different. Therefore we changed the atmosphere from high vacuum to argon atmosphere at 950°C and 1000°C, but we could not observe any appearance of new grains at all.
(4) As regards the surface grain growth of 0.2%C steels in various atmospheres, it was observed that the lower the degree of vacuum or the higher the argon pressure, the higher became the grain coarsening temperature.
(5) Remarkable grain growth which occurred at about 950°C in high vacuum within several microns in depth from the specimen surface, took place even when mechanically polished surface was removed by electrolytic polishing.
(6) It is very convenient to determine the austenite grain size continuously with the high temperature microscope. So far as this study is concerned, the value of surface grain size in 0.6∼1.0 atm. argon was nearest to that of inner grain size. In the high temperature microscope observations, however, the atmosphere must be selected cautiously and careful considerations are required to discuss the inner states of the specimen according to the experimental results of the specimen surface only. It may be also said that these cautions are applicable to the determination of the austenite grain size by oxidation method.View full abstractDownload PDF (1860K) -
Kichizo Niwa, Satoshi Kado, Shuji Inagaki1964 Volume 28 Issue 6 Pages 348-353
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe diffusion coefficients of silver in the lead-tin system have been studied at the concentrations of tin NSn=0.223, 0.405, 0.614 and 0.799 and the temperature ranges of 410°∼557°, 453°∼609°, 391°∼609° and 405°∼690°C, respectively. The results can be represented by the equations:
(This article is not displayable. Please see full text pdf.)
\ oindentWith aid of thermodynamic properties of the Pb-Sn systems and supposing
(This article is not displayable. Please see full text pdf.)
\ oindentthe diffusion coefficients of tin in Pb-Sn systems at 500°C have been calculated by the equation
(This article is not displayable. Please see full text pdf.)
\ oindentThe calculated values of diffusion coefficients at various compositions agree well with those experimentally obtained in a previous study.View full abstractDownload PDF (1583K) -
Kichizo Niwa, Satoshi Kado, Hiroshi Nakajima, Kazuhiko Ichikawa1964 Volume 28 Issue 6 Pages 353-359
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe diffusion coefficients of silver in molten lead-bismuth and tin-bismuth alloys have been measured over the temperature ranges from 420° to 623°C and from 439° to 628°C respectively, using the capillary method and Ag110 as the radioactive tracer.
The results can be represented by
(This article is not displayable. Please see full text pdf.)
Using these results, the diffusion coefficients of bismuth in molten lead-bismuth and tin-bismuth alloys can be calculated from the following equations:
(This article is not displayable. Please see full text pdf.)
The obtained results are in agreement with the previous experimental data within the experimental error.View full abstractDownload PDF (1188K)
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