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Volume 45, Issue 7
Displaying 1-16 of 16 articles from this issue
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Osamu Nakano, Hisaoki Sasano, Toshiyuki Suzuki, Hirozo Kimura1981 Volume 45 Issue 7 Pages 653-660
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to confirm the existence of the miscibility gap in Ti-V system electrical resistivity measurements and X-ray diffraction analysis were carried out for the alloys containing 5∼50 mass%V.
Temperature dependence of electrical resistivity suggests that monotectoid reaction of β→β1+β2 occures at temperature above 948 K. A pair of diffraction lines observed in the X-ray diffraction pattern for the alloys containing 30, 40 and 50 mass%V after aging at temperatures between 973 and 1073 K for more than 7.2 Ms are considered to be direct evidence to prove the decomposition of β phase.
The present results indicate that a miscibility gap of β→β1+β2 exists in the range above 948 K and at more than 20 mass%V. The results also indicate that the transformation of β→β+α occurs around 948 K.View full abstractDownload PDF (782K) -
Yoshiki Seno, Isao Iwanaga, Yoshitsugu Tomokiyo, Tetsuo Eguchi1981 Volume 45 Issue 7 Pages 661-667
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to analyze the process of precipitation in Cu-Co alloys which are well known to show superparamagnetic behaviours, applicability of magnetic measurement for the alloys has been disscused. Important points to be noted are: (1) When the aging temperature is below about 873 K the discontinuous precipitation on grain boundaries and dislocation lines has an effect on the magnetization curve, and this effect should be taken into account in the analysis. It is negligible, however, when the aging temperature is above about 873 K. (2) The magnetization curve is not sensitive to the details of the particle size distribution, and only the mean particle size must be taken into account in the analysis. (3) When the mean particle radius is larger than 4.0∼4.5 nm, the magntic behaviour of the specimen deviates from the superparamagnetism, and the Langevin function cannot be used for the analysis.
The process of precipitation has been investigated for Cu-Co alloys aged at 873 K by magnetic measurement. Electron microscopic observation has been carried out supplementally for the specimen in which precipitated particles were large in size. The rate of increase of the mean particle radius obtained from the magnetic measurement has been shown to be in good agreement with that obtained from the electron microscopic observation. It has been found that this rate is proportional to the cube root of the aging time and that it is almost independent on the composition of the alloy. The latter is not in agreement with the result of Livingston.View full abstractDownload PDF (578K) -
Hitoshi Iwasaki, Osamu Nittono, Yasumasa Koyama1981 Volume 45 Issue 7 Pages 667-675
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe fct(β,c⁄a<1)\ ightleftarrowsfct(α′,c⁄a>1) phase transformation in indium-rich tin solid solutions has been studied by means of X-ray and electron diffraction, with supplement of metallographic observations. The β\ ightleftarrowsα′ phase transformation is of the diffusionless (martensitic) kind, and takes place with a mechanism involving cooperative atomic movements. The atomic movements of the phase transformation can be explained by considering a coupling of two predominant TA1 phonon modes with low frequencies, as in the cases of the In-Tl, In-Cd and In-Pb alloys. After the reverse transformation (α′→β) upon heating, the orientations of the reverted β phase crystal do not always agree with the original ones of the initial β phase (matrix) crystal, i.e. the β\ ightleftarrowsα′ phase transformation is not always crystallographically reversible. It was also found that the indium-tin alloys are slightly decomposed during heating for the reverse transformation; the decomposition process depends strongly on the grain size. The behavior of forward and reverse transformations is quite similar to that of the burst type in Fe-Ni alloys, although for the latter a decomposition process does not interfere with the transformation. It is concluded that the partial shape recovery is mainly associated with an imperfect crystallographical reversibility and also that a gradual decrease in shape memory effect, which was observed after keeping at room temperature for a long period of time, is related with the intermediate stage of α′→(α+β) decomposition. The imperfect crystallographical reversibility may result from the large atomic displacements of the phase transformation.View full abstractDownload PDF (1308K) -
Koichi Yamaguchi, Seiichi Nishikawa1981 Volume 45 Issue 7 Pages 675-682
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe decomposition of super saturated solid solution of aluminum alloys is generally considered to occur very rapidly even at room temperature, and so the techniques of quenching and handling a specimen bring important effects on experimental results. In the present study, a cryostat for small angle X-ray scattering has been improved in order to set a quenched specimen into the apparatus within a few seconds under 200 K. The aging processes at the vicinity of 273 K in Al-2.4 at%Ag and Al-9.4 at%Zn alloys are investigated. At an early stage of aging an increase in the integrated intensity of diffuse scattering is observed. The relation of Porod’s approximation can not be applied to this stage, and a linear relation between logarithms of intensity and aging time is obtained by Rundman’s method. The above results show that a spinodal decomposition occurs at this stage. The spinodal temperatures of the two alloys are 413 K and 333 K, respectively. A transient stage is observed before the normal spinodal decomposition by Cahn’s theory, at which the intensity of diffuse scattering increases over the whole range of scattering angle. The transient phenomenon is considered as the results of complex interactions among the concentration fluctuations before and after aging and the rapid decay of quenched-in vacancies. The initial stage of aging of these alloys is concluded to be subdivided into the three stages; the first is a transient stage, the second is a spinodal stage, and the third is a stage of reaction saturation.View full abstractDownload PDF (643K) -
Makoto Kikuchi, Si-Kyung Choi, Yasutsugu Ogura, Ryohei Tanaka1981 Volume 45 Issue 7 Pages 683-690
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo study cellular precipitations with carbide or nitride as the precipitate, high chromium-high nickel austenitic steels with 0.4 per cent nitrogen were chosen as a model system. Two austenitic steels with the composition of 25%Cr-28%Ni-0.40%N and 25%Cr-20%Ni-0.41%N were aged at 1073 K and growth characteristics of cellular precipitation of Cr2N were investigated.
All the following growth characteristics are quite different from the well known growth characteristics of cellular precipitations in binary substitutional systems. (A) Average migration rate of the free interface between untransformed matrix and cell decreases with reaction time. Cell growth stops even when the large portion of the specimen still remains untransformed with substantial supersaturation. This leads to the result that only a part of the specimen decomposes into cell. The rest remains untransformed even after a prolonged aging. (B) The observed volume fraction of Cr2N precipitates inside the cell is much larger than the calculated one based on the matrix-precipitate equilibrium in the original solid solution. Average nitrogen concentration inside the cell becomes higher than that of the original solid solution. In contrast to this, nitrogen concentration in the untransformed matrix outside the cell decreases with reaction time. (C) The volume fraction of Cr2N precipitates inside the cell decreases with reaction time.
These unusual characteristics can be ascribed to the long range diffusion of nitrogen. It is suggested that the redistribution of solutes accompanying the cellular precipitation of Cr2N takes place through grain boundary diffusion of chromium and long range volume diffusion of nitrogen. The present behaviors are expected to be generally observed in any cellular precipitation of carbide or nitride.View full abstractDownload PDF (966K) -
Kazuyuki Mizuhara1981 Volume 45 Issue 7 Pages 691-697
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA new experimental technique and set-up for measuring the optically stimulated exo-electron emission (OSEE) is developed. In order to obtain the test surface of uniform quality and to realize the stable OSEE measurement, orthogonal cutting was conducted in a vacuum chamber and a monochromatic light was focused on the finished metal surface during the cutting. By changing the location of the focused light, it is possible to measure OSEE at arbitrary time after the surface creation.
The adsorption process of gas molecules to the surface can be studied by comparing the electron energy distribution with the emission intensity distribution which are obtained for various atmospheres with changing the wave length of stimulating light. It is found that adsorption of water and methanol molecules (of which dipolemoment 6.17×10−30 C·m and 5.64×10−30 C·m respectively) enhances OSEE and reduces the work function about 0.5 eV, while the adsorption of carbon-tetrachloride and benzene (of which dipolemoment are zero) does not show any effect.
According to the emission characteristics obtained, it appears that the machined surface may consist of portions of different work function and the well known change of contact potential with time elapsed after the surface creation may be attributed to the change of area ratio of the portions.
On adsorbed copper surface an emission center which is similar to what observed in oxides and alkali halides was found.View full abstractDownload PDF (574K) -
Yasuo Uchiyama, Hideto Koga, Hiroaki Inokuchi1981 Volume 45 Issue 7 Pages 697-703
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of immersion temperature on the reaction between Fe-Si alloys and liquid zinc was studied to obtain information about the effect of Si on the Fe-Zn reaction. Seven Fe-Si alloys with different Si concentrations (0.10∼2.84 mass%) were immersed in pure molten zinc for 600 s in the temperature range of 713∼873 K. The results obtained are as follows:
(1) The δ1 layer is formed next to the Γ layer. The type of alloy layer formed next to the δ1 layer depends on the Si concentration and immersion temperature.
(2) The reaction between iron and zinc proceeds rapidly for the Fe-0.10%Si alloy at 713 K and for the Fe-1.15%Si alloy at 793 K.
(3) An addition of 0.10%Si affects the formation and growth of the ζ layer, and an addition of about 1.15%Si affects the growth of the (δ1+η) layer.
(4) The reaction between iron and zinc at temperatures above 813 K does not depend on the Si concentration in the Fe-Si alloys.View full abstractDownload PDF (662K) -
Tohru Yamasaki, Hisashi Izumi, Hisakichi Sunada, Yukio Kondo1981 Volume 45 Issue 7 Pages 704-710
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe microstructure of electroless deposited Ni-P alloys in the composition ranging from 5.3 to 7.9 mass%P has been studied by a large angle X-ray scattering method. The changes of microstructure and mechanical properties by cyclic stressing at various stress levels were examined by a X-ray scattering technique and also by a static bend test.
The results obtained are as follows;
(1) The microstructure of electroless Ni-P alloys containing less than about 7 mass%P is a supersaturated solid solution of fcc Ni in which an excess of P dissolves. On the other hand, the electroless Ni-P alloys containing more than about 7 mass%P are completely amorphous structure. This structure is quite similar to that of the amorphous alloys obtained by other methods such as rapid quenching and electrodeposition.
(2) The amorphous Ni-P alloys prepared by the present method have some excellent properties such as good ductility and high corrosion resistance. But, these excellent properties deteriorate by cyclic stressing, particularly by tensile stressing, because of a changes in amorphous structure due to structural relaxation and local crystallization.View full abstractDownload PDF (885K) -
Minoru Nobuki, Atsushi Oguchi1981 Volume 45 Issue 7 Pages 711-717
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCompression and sheath forging tests have been performed at high temperatures up to 1500 K for as-cast Alnico 5 and Sendust alloys which are brittle even at temperatures higher than Tm⁄2 (Tm: melting point). And the effects of various working factors and separation to dual phase on deformability, flow stress and microstructure of deformed materials have been examined.
A large compressive strain more than 1.5 was obtained for Alnico 5 in the temperature range from 1350 to 1600 K and for Sendust in the range from 1050 to 1500 K at a strain rate of 0.0011 s−1.
Materials deformed in the ductile range showed homogeneous fine structure. In the case of the Alnico alloy, the ductile temperature range was extended to lower side by the separation to dual phase.
The deformability in the ductile range depended strongly on the strain rate, and at strain rates higher than 100 s−1 grain boundary brittle fracture appeared in all specimens.
By the forging using a miled steel sheathed billet at a temperature of 1470 K and a strain rate of 1 s−1, a forging ratio more than 7 was obtained for both materials without cracks.View full abstractDownload PDF (1479K) -
Osamu Momose, Sosuke Uchida1981 Volume 45 Issue 7 Pages 718-722
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe nitrosulfurized layer and wear property of gas nitrosulfurized alloy steels were discussed. A test pieces of SNC 631, SCr 430 and S45C steels were treated in an atmosphere of the 50%NH3, 0.02%H2S and propan converted carrier gas mixture in the temperature of 843 K for 10.8 ks. It was confirmed by X-ray diffraction that the main surface products were Fe1−xS, FeS, Fe3N and Fe4N at each specimens. The compound layer was observed on the cross sectional microstructure of treated specimens. The hardness of compound layer was become hard in the order of S45C, SNC 631 and SCr 430. The wear test was carried out under the condition of 490 kPa using pin-ring system wear tester without lubrication. It was found that the gas nitrosulfurizing of steels were improved wear resistance of steels because the compound layer which was formed on the treated specimens was reduced the adhesion of the sliding plane and those effect was remarkable on the alloy steels.View full abstractDownload PDF (459K) -
Fujio Urushihara, Shigeo Sato1981 Volume 45 Issue 7 Pages 723-731
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe metastable precrpitates and the miscibility gap of Fe-W-Co ternary alloys were investigated during isothermal aging at 773∼1073 K by means of Vickers hardness test, X-ray diffraction, DTA and electron microscopy. Specimens in the composition of 5 to 30 mass%W and 0 to 50 mass%Co were used in this experiment. The results obtained are as follows.
(1) During isothermal aging at 773 K and 873 K, the metastable bcc η phase was found in the composition of 35%Co or less and the metastable hcp Co3W phase was found in the composition of 40%Co and above.
(2) During aging at 973∼1073 K, the λ phase (Fe2W) was found as the equilibrium precipitate in many alloys, but in high W and high Co alloys μ phase (Fe7W6) was found.
(3) The thermodynamic interaction parameters for the bcc phase of the binary system was estimated by investigating the phase equilibria in the Fe-W binary phase diagram and the effect of addition of W on the order-disorder transition temperature of FeCo superlattice. The chemical binodal and spinodal lines was calculated by the simple regular solution approximation.View full abstractDownload PDF (757K) -
Yukiteru Asayama1981 Volume 45 Issue 7 Pages 731-739
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPrecipitation processes were investigated with precipitation hardening stainless steels, 15-5 PH, PH13-8Mo and 17-7PH, by means of the measurement of electrical resistivity.
Metastable precipitation, P1, was found at about 690 K in all the steels in the measurement of electrical resistivity change during isochronal aging. P1 was detected more evidently during re-aging at low temperature (670∼750 K) after high temperature aging at 833 K and 873 K. The value of apparent activation energy for P1 was obtained as 200 kJ/mol.
From the precipitation behavior of the steel 15-5PH, the metastable precipitation, P1, was assumed to be due to the formation of Ni-rich zone.
Embrittlement characterized by the decrease in notch tensile strength occurred when the steels were aged at temperatures ranging roughly from 670 K to 750 K. The embrittlement was also caused by the re-aging at low temperatures after the high temperature aging. The decrease in hardness due to over-aging raised again the notch tensile strength.
From these experimental results it was suggested that the embrittlement is closely related to the precipitation of Ni-rich zone, and that the increase in hardness is necessary for the occurrence of the embrittlement.View full abstractDownload PDF (953K) -
Nobuyuki Koguchi, Katashi Masumoto1981 Volume 45 Issue 7 Pages 740-745
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt is necessary to prepare epitaxial thin films of the ternary compound ferromagnetic semiconductors such as HgCr2Se4 or CdCr2Se4 for investigation of the anomalous optical properties of these materials and the new opto-electronic devices using these properties.
Epitaxial thin films of solid-solution HgxCd1−xCr2Se4 with graded-composition profiles were prepared on CdCr2Se4 single crystal substrates by holding the substrate and HgCr2Se4 source separately at a temperature above 823 K in a sealed quartz ampoule.
The isothermal epitaxial growth of HgxCd1−xCr2Se4 solid-solution thin film is caused by vapor-solid type diffusion, in which a high partial vapor pressure component (Hg) is diffused from the vapor phase into a CdCr2Se4 substrate.
The interdiffusion coefficient \Bar{D} of Hg and Cd in the HgxCd1−xCr2Se4 solid-solution were determined from the composition profile as a function of mole fraction x.View full abstractDownload PDF (580K) -
Tetsuo Yano, Osamu Yanagisawa1981 Volume 45 Issue 7 Pages 745-751
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe Al-Al3Ni eutectic composites were tested in tension at temperatures from 293 K to 773 K and at strain rates from 9.3×10−6 s−1 to 9.3×10−2 s−1. The tensile deformation and fracture behaviors were investigated by an optical and scanning electron microscopy. The shape of stress-strain curves, microstructure of longitudinal sections near fracture surface and fractography were roughly divided into two groups; one is observable at low temperature-high strain rate, the other is at high temperature-low strain rate. Thus, it seems that the ultimate tensile strength is decided by the nucleation of sharp cracks in the former case, while it is by the formation of shear deformation bands in the latter one.View full abstractDownload PDF (1010K) -
Itsuo Ohnaka, Tatsuichi Fukusako, Tetsutaro Ohmichi1981 Volume 45 Issue 7 Pages 751-758
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA new method is proposed, which can directly produce continuous filament with round cross-section from molten metal. In this method molten metal jet is ejected into the water layer formed on the inner surface of a rotating drum. Production examples of lead and Pd-alloy filaments are presented. In addition, the relation between the continuity, surface appearance and cross-section of lead filament and spinning conditions, such as drum speed, jet speed, incidence angle of jet into the water layer and water thickness, is discussed. This method may be applicable to the production of amorphous metal filaments with round cross-section.View full abstractDownload PDF (1124K) -
Shuji Hanada, Takashi Sato, Sadao Watanabe, Osamu Izumi1981 Volume 45 Issue 7 Pages 759-760
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (411K)
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