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Volume 47, Issue 11
Displaying 1-17 of 17 articles from this issue
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Akitoshi Yamamoto, Nobutaka Narita, Jin-ichi Takamura, Hiroki Sakamoto ...1983 Volume 47 Issue 11 Pages 903-911
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe validity of our nucleation model of deformation twinning previously proposed for fcc metals has been quantitatively examined to determine the stacking fault energy γSF from the twinning stress τT, with particular attention to the orientation dependence of τT of pure copper crystals deformed in tension at 4.2 K. Main results obtained are summarized as follows:
(1) τT in Cu crystals is decreased as the specimen axis approaches [111] from [100] when twinning occurs in stage III, while in stage II little affected by the orientation. This orientation dependence, consistent with that previously observed in pure Ag and Cu alloy crystals, can be quantitatively explained by our model.
(2) The value of γSF of pure Cu at 4.2 K has been evaluated as 43.5±2 mJ/m2 from the twinning stress τT by using the equation derived from our model.
(3) Upon nucleation of twins, the critical internal stress acting on the twinning dislocations, which arises from a dislocation pile-up in our model, is about 1.3 times as large as the applied stress in Cu crystals tested at 4.2 K. This ratio of internal stress to applied stress is the same as that previously reported in Ni-based alloys.
(4) By using this stress ratio, the equation derived from our model is simplified with good approximation as γSF=ξ(R)τTbS, where ξ(R) is a parameter depending only on the specimen orientation and bS the Burgers vector of a Shockley partial dislocation.
(5) This simplified formula can be applied to the case in which twinning occurs not later than early stage III where the relief of internal stress is ignored. Under this condition, the value of γSF in fcc metals and alloys is directly determined from τT in specimens oriented near [211] by a formula, γSF=2τTbS.View full abstractDownload PDF (1640K) -
Mineo Kogachi, Sanae Ishibata1983 Volume 47 Issue 11 Pages 912-918
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe change in axial ratio c/a of the CuAu L10-type ordered alloy with the addition of the third element X was examined. All the ternary alloys prepared were constructed by substituting X for corresponding amount of Au in the CuAu, where X was Ni and Ag. Further, Cu-Au binary system was picked up. The results obtained by X-ray diffraction method showed that, the axial ratio increased with composition y, fairly rapidly for the CuAu1−yNiy and gradually for the CuAu1−yAgy. In the Cu-Au system, it increased with deviation of composition from stoichiometry.
The experimental results, together with those published before for the CuAu1−yPdy, were analized taking into account of two energy terms; the repulsive interaction acting between ion cores and the electrostatic energy of ions occupying lattice sites. They were expressed as a function of the axial ratio by applying the Bragg-Williams method. The numerical results of c/a under the assumption of maximum degree of order S explained qualitatively the observation in the Cu-Au and CuAu1−yPdy but failed for the CuAu1−yNiy and CuAu1−yAgy. For the latter two systems, however, using the values of S obtained from X-ray intensity measurements, the recalculated results reproduced well the observed facts.View full abstractDownload PDF (942K) -
Yasumasa Koyama, Toshiyasu Ukena, Kazuo Morikawa, Osamu Nittono1983 Volume 47 Issue 11 Pages 919-926
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSChanges in both crystal structure and surface relief during the phase transformation in Indium-(13−X) at%Pb-X at%Sn pseudobinary alloys have been studied by means of metallurgical techniques. Lattice parameters at each temperature during the phase transformation show that the alloys undergo two kinds of phase transformation: fct(c⁄a<1)↔fco phase transformation in the alloys containing (0-9) at%Sn and fct(c⁄a<1)↔fct(c⁄a>1) one in the alloys containing (11-13) at%Sn. The characteristic feature of phase transformation becomes more recognizable first-order gradually with increasing tin content. The appearance of a banded surface relief in a low-temperature phase concludes that these phase transformations are martensitic ones taking place by the cooperative movement of atoms. The change in surface relief is reversible in the alloys containing (0-7) at%Sn, but not in others. Corresponding to this, the amount of shape recovery in the former alloys is nearly constant, and the latter alloys show a decrease in shape recovery with increasing tin content. The characteristic features of shape recovery associated with phase transformation on heating is discussed in terms of the crystallographic reversibility in each phase transformation. Furthermore, the fct(c⁄a<1)↔fco phase transformation is analyzed phenomenologically on the basis of the Landau theory, and some physical quantities such as the change in entropy and the elastic constant C′ are calculated. The temperature dependence of the stress-strain relation is also discussed in terms of ferro- and super-elasticity. The analyzed results suggest that the characteristic behavior of the fct(c⁄a<1)↔fco phase transformation depends upon the average atomic size as well as the valence electron concentration.View full abstractDownload PDF (1164K) -
Hideki Tonda, Shunji Fujiwara, Tatsuo Kawasaki1983 Volume 47 Issue 11 Pages 927-932
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe tensile deformation behavior by {11\bar22}⟨\bar1\bar123⟩ slip of zinc thin sheet crystals was investigated at the temperature range from 168 to 423 K. It became clear by the observations of slip lines and etch pits that the deformation mode in yielding at temperatures lower than room temperature was inhomogeneous, while that at temperatures higher than r.t. was homogeneous. The mean free path of edge dislocations decreased with increasing temperature. A yield stress-temperature curve showed a negative slope at the low temperatures and a positive slope at the high temperatures. The former dependence was explained by the Peierls mechanism, and the latter dependence by the thermally activated conversion from glissile edge dislocation to sessile one. The work hardening ratio increased rapidly with increasing temperature. It was found that m=1.43 and n=0.57 at 207 K and m=0.48 and n=0.19 at r.t. in the relationships of ρ∝σm and ρ∝εn, where ρ is the dislocation density, σ the flow stress and ε the strain. The unload hardening in the work hardening stage at 207 K increased with increasing unloading time. It was concluded that the work hardening at 207 K was controlled by prismatic loops.View full abstractDownload PDF (1261K) -
Yoshihito Shigeno, Hiroyuki Mitsufuji, Masanori Tokuda, Masayasu Ohtan ...1983 Volume 47 Issue 11 Pages 933-941
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDecarburization of iron with a high carbon content is one of the main reactions in the coal gasification process using molten iron bath, where O2 or H2O is used as an oxidizing agent. In this process, sulphur accumulation through direct dissolution of coal into the melt may influence the decarburization rate.
In the present study, high carbon iron was decarburized by blowing H2-H2O and CO-CO2 gas mixtures on the metal surface in the temperature range between 1673 and 1873 K. Influence of sulphur on the rate of decarburization was also studied.
The results were summarized as follows.
(1) The following non-dimensional correlation was found in the regime of mass transfer control in the gas phase.
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(2) When sulphur was added, a negative deviation from the above relationship was observed. This might be due to the mixed control of mass transfer in the gas phase and the chemical reaction on the iron surface.
Much more deviation for CO-CO2 than for H2-H2O was observed. It was attributed to the fact that the apparent rate constant for dissociative chemisorption, kC, of H2O was much greater than that of CO2. The ratio between the rate constants was estimated to be more than ten at about 0.4 mass%S.
(3) The rate constant for dissociative chemisorption, kC0, of H2O was found to be 30-80 times as large as that for CO2 on the basis of the sulphur blockage mechanism by chemisorbed sulphur. It was concluded that this difference in the kC0-values may cause the stronger influence on the rate of decarburization with CO-CO2 by the chemisorbed sulphur.View full abstractDownload PDF (1107K) -
Kazuhiro Yoshihara, Kazuyoshi Nii1983 Volume 47 Issue 11 Pages 941-949
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe surface composition of 18-8 stainless steel doped with boron and nitrogen at high temperatures was observed in vacuum with AES and XPS.
The precipitation of boron nitride was found on the surface of the stainless steel. At the first stage of heating, a thin layer of boron nitride flowed out from grain boundaries and spread on the surface, replacing phosphorus and sulfur which segregated all over the surface. As the heating time was prolonged, parts of the thin layer of boron nitride increased in thickness. The thickness increased in proportion to the square root of heating time and became about 0.06 μm after heated at 1100 K for 432 ks. The precipitated boron nitride was not replaced by the most surface active element, sulfur, and remained stable on the surface. On the surface of the stainless steel, however, there existed areas not covered with boron nitride after prolonged heating. On these uncovered areas, sulfur segregated.
The precipitated boron nitride layer was inert to the adsorption of gases. Therefore, this stainless steel is a superior candidate material for vacuum vessels.View full abstractDownload PDF (1780K) -
Takayoshi Yoshimori, Jiro Murayama, Shoichiro Usuki, Akihiko Yamauchi1983 Volume 47 Issue 11 Pages 950-955
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWater on aluminium surface was liberated by stepwise heating of a sample in an IR radiation furnace, and determined by the coulometric titration method after conversion into ammonia. Adsorbed water on the oxide layer formed on aluminium surface was first removed at 373 K, and combined water in the layer was liberated between 673 and 873 K. No water liberation could be found at 473 and 573 K, but some hydrogen was generated at 573 K by the reaction between the water and aluminium. The amount of each kind of water increased appreciably by the storage of the samples in an hygrostat after their surface treatments. However, the amounts of water liberated between 673 and 873 K were nearly constant, when the samples were analysed immediately after their surface treatments. Therefore, the correction of combined water for the determination of hydrogen in the metal was partly possible, when the sample was heated by two steps. After removal of adsorbed water at 373 K, the sample was heated at 873 K for the determination of both hydrogen and water, and the amounts of 873 K water measured separately was deducted from the previous result. However the error due to the reaction between water and the metal found at 573 K cannot be corrected irrespective of the method of hydrogen determination, though it may be reduced by taking a large amount of the sample.View full abstractDownload PDF (771K) -
Hiroshi Okusu, Shinji Takeshita, Kazuichi Mizoguchi, Yukio Suginohara1983 Volume 47 Issue 11 Pages 956-963
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe improved trimethylsilylation method reported previously was used to measure variation in the distribution of silicate anions in lead silicates on heating glassy samples with various molar ratios (PbO/SiO2=4, 3, 2, 1.5 and 1) at various temperatures. By combining the above results with IR and X-ray powder data it was possible to determine the type and the amount of silicate anions in the various known lead silicate compounds which were produced during crystallization.
Results of these experiments are summarized as follows:
(1) During crystallization of 4PbO·SiO2 glass the formation of the γ- and α-4PbO·SiO2 compound was observed, and the former consisted mostly of Si2O76− and SiO44−, and the latter comprised mainly SiO44−.
(2) Heat-treatment of 3PbO·SiO2 glass produced two known modifications, phase P and Pb3SiO5, designated by Smart et al., and the former was mainly composed of Si2O76−, SiO44− and polysilicate anion, the latter containing mostly Si2O76−.
(3) During crystallization of 2PbO·SiO2 glass the production of various modification forms (T-, M1-, H-Pb2SiO4) was recognized. In T-Pb2SiO4 Si2O76− prevailed, M1-Pb2SiO4 contained predominantly Si4O128− ring and H-Pb2SiO4 was composed of polysilicate anion.
(4) Heat-treatment of 3PbO·2SiO2 glass produced phase X0, whose structure was found to be different from that of barysilite obtained from undercooled melts.
(5) Heat-treatment of PbO·SiO2 yielded L(low)-PbO·SiO2 and Alamosite, which were considered to be composed of highly polymerized silicate anion, because the trimethylsilylated derivatives could hardly be detectable gas-chromatographically.View full abstractDownload PDF (1129K) -
Yoshitake Nishi, Hikaru Aoyagi, Etsujiro Yajima1983 Volume 47 Issue 11 Pages 964-969
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSChanges in mechanical properties are investigated for rapidly solidified Cu-Ti binary alloys during aging by means of tensile tests, micro-Vicker’s hardness measurements and X-ray analysis. Aging induces high rigidity and ductility for rapidly solidified Cu90Ti10 crystalline alloys. Rapid solidification accelerates the spinodal decomposition and solves excess solute atoms (Ti) in the matrix. The excess solute atoms increase the flow stress. Cold-work before aging induces large maximum hardness and accelerates the spinodal decomposition. The form of this transformation is independent of rapid solidification, excess solute atoms and cold-work. Furthermore, it is proposed that the hardness and aging time to maximum hardness are estimated by the use of various hardness factors and multiplying factors, respectively.View full abstractDownload PDF (1241K) -
Satoshi Takahashi, Nobuyuki Koguchi, Katashi Masumoto1983 Volume 47 Issue 11 Pages 970-977
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPolycrystalline thin films of the ferromagnetic semiconductor HgCr2Se4 have been prepared for the first time on insulating MgAl2O4 single crystal substrates by molecular beam deposition and subsequent annealing with HgSe.
Measurements of absorption spectra for the thin films of HgCr2Se4 were made at 295, 95 and 25 K in the photon energy from 0.5 to 3.0 eV. It becomes evident that there exists an absorption band with a maximum at about 0.93 eV at 295 K. This absorption band shows a red-shift phenomenon, with decreasing temperature, corresponding to the transition from the valence band to the narrow conduction band which is caused by s-d interaction and s-d hybridization. Furthermore, we found that there exist other transitions with energy gaps of 1.20, 1.47 and 1.90 eV at 295 K.
As a result of this investigation we point out the possibility of making tunable lasers from this material.View full abstractDownload PDF (1045K) -
Masamichi Miki, Yoshikiyo Ogino1983 Volume 47 Issue 11 Pages 977-982
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe characteristics of the cellular precipitation in Ni-8 mass%Sn and Ni-15 mass%Sn alloys on aging at 823 K after quenching from 1273 K was investigated by means of quantitive metallographic methods and X-ray analysis. Results obtaindd are as follows:
(1) The cellular precipitation in these alloys proceeded in three stages. Before the first cell with fine lamellae engulfed entirely all the matrix, the second cell with coarse lamellae began to grow into the first cell. After the second cell engulfed almost all the first cell, the third cell with coarser lamellae began to grow into the second cell.
(2) The lattice parameter of the α phase in the cell decreased gradually untill the finish of the second cellular precipitation. The precipitates in the cell was an equilibrium phase (Ni3Sn) with DO19 type structure.
(3) The growth rate of the second cell is 1/20-1/30 times as large as that of the first cell. The interlamellar spacing of the second cell is 2-3 times as large as that of the first cell.
(4) The area fraction of the cell, X, can be represented by Johnson-Mehl’s equation; X=1−exp(−btn), and 1.0-1.2 and 0.6-0.7 were obtained as the values of n for the first and second cell, respectively.
(5) A precipitate free zone was observed near by the grain boundary before the growth of the first cell.View full abstractDownload PDF (1106K) -
Masamichi Miki, Yoshikiyo Ogino1983 Volume 47 Issue 11 Pages 983-990
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe influence of the addition of B and P on the cellular and intragranular precipitation in Ni-8-15 mass%Sn and Cu-10-80 mass%Ni-8 mass%Sn alloys was investigated by means of quantitative metallographic methods. Results obtained are as follows:
(1) The intragranular precipitation in these alloys was inclined to be retarded by the addition of B and P.
(2) The cellular precipitation in these alloys was significantly suppressed by the addition of B and P. The suppressing effect of B and P depended upon the Ni concentration in the Cu-Ni-Sn alloys and was especially large in the 40-60%Ni alloys.
(3) The suppressing effect of P was larger than that of B. Those of B and P increased with increasing amount of addition.
(4) It is considered that B and P segregated at the grain boundary and suppressed the nucleation and growth of the cell.
(5) The suppressing effect of B and P depended upon the growth rate of the cell in the B and P free specimen, and was remarkable in the case of the small growth rate of cell.View full abstractDownload PDF (2422K) -
Yoshihito Matsumura, Yen C. Huang1983 Volume 47 Issue 11 Pages 991-997
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSProperties of silicon nitride films formed by the HCD (Hollow Cathode Discharge) ion plating process were studied. Defect density of films as a function of film thickness was also measured. Silicon was evaporated in nitrogen gas atmosphere with the HCD plasma electron beam and deposited on p-type (100) oriented silicon substrates. It was found that with increasing nitrogen partial pressure the electrical resistivity, the relative dielectric constant and the hardness of films increased, and that the infrared absorption peak wavelength and the refractive index of films decreased.
The HCD ion plating process made it possible to form silicon nitride films at a low substrate temperature (473 K) and a high deposition rate (10 nm/s), and the properties of films deposited were comparable to those formed by the CVD or plasma CVD processes.View full abstractDownload PDF (938K) -
Setsuo Takaki, Eiji Nakano, Youichi Tokunaga1983 Volume 47 Issue 11 Pages 998-1003
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA 20%Cr-11%Co steel has a ferritic structure after water quenching from 1523 K (α steel), while it has a mixed structure of 70% martensite and 30% ferrite after water quenching from 1223 K ((α′+α) steel). In the present study, the effects of the initial structure and cold working on the formation of Cr-rich phase during aging, which leads to the 475°C embrittlement, and also on the mechanical properties of the specimens aged at 748 K (475°C) were investigated by means of calorimetric analysis and tensile testing.
Main results obtained were as follows.
(1) The formation of Cr-rich phase in α-steel is accelerated by cold working prior to 748 K aging.
(2) The formation behaviors of Cr-rich phase by 748 K aging are almost identical in the cold worked α steel and the (α′+α) steel.
(3) The emblittling in the (α′+α) steel is remarkably retarded because of the finely dispersed martensite, in spite of the acceleration of Cr rich phase formation. For example, the elongation is about 10% even after 1000 ks aging.View full abstractDownload PDF (1240K) -
Yasunori Miyata, Toshio Suzuki, Yoshiyuki Yasutomi1983 Volume 47 Issue 11 Pages 1004-1009
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSInterfacial stability conditions of Al-Cu alloys were investigated under gravity force and centrifugal forces of 2G and 5G. Specimens were unidirectionally solidified and quenched during solidification. Stability conditions under the acceleration of 1G, 2G and 5G were determined. The result in 1G experiments agrees with those in other works. On the contrary, planer interfaces under additional acceleration are more unstable than that in 1G experiments under the same conditions. The equilibrium partition coefficient, k, and the diffusion coefficient of copper in the melt D, were determined by XMA analysis.
Determined values for 1G, 2G and 5G experiments are 0.163, 0.162 and 0.162, and 4.76×10−9, 4.53×10−9 and 4.58×10−9 m/s, respectively. Decrease of diffusion coefficient is presumably due to gravity segregation and pressure enlarged by additional acceleration. The extension of unstable regions in 2G and 5G experiments is attributed to this decrease of the diffusion coefficient and some micro convection which may be enlarged by additional acceleration.View full abstractDownload PDF (1190K) -
Itsuo Ohnaka, Isamu Yamauchi, Mitsuhiro Morimoto, Tatsuichi Fukusako1983 Volume 47 Issue 11 Pages 1010-1015
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA new atomization process for metal powders is proposed, in which molten metal jet is atomized by impact of a rotating toothed-disk and atomized droplets are cooled by gas jet or liquid. Atomization trials were made by using an Fe40Ni40B20 alloy and cooling in water layer formed in a rotating drum installed around the disk. The mean particle size of the powder decreased with increasing rotational speed of the disk and molten metal ejection pressure and with decreasing ejection nozzle diameter. Under the same rotational speed and nozzle diameter, the mean particle size was smaller than that by the rotating-water-atomization process. The powder shape was almost spherical. About 20 percent of the powder was amorphous (the cooling rate ranging between 105 and 106 K/s), and the rest was estimated to be partially solidified in the air between the disk and the water surface (the cooling rate ranging between 102 and 104 K/s). The cooling rate may be increased by improvements of the process. This process may be useful for producing fine and rapidly solidified metallic powders.View full abstractDownload PDF (2132K) -
Isamu Yamauchi, Satoru Kawamoto, Itsuo Ohnaka, Tatsuichi Fukusako1983 Volume 47 Issue 11 Pages 1016-1021
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe rotating-water-atomization process was applied to get rapidly solidified Al-4.5%Cu powder. The shape of the obtained particles were not spherical but tear-drop-like. At the lower water-surface velocity, powders contained a small amount of acicular particles. The mean particle size \barDp (μm) decreased with increasing water-surface velocity Vw (m/s) and with decreasing cross sectional area of ejection nozzle, Sn (mm2), and it was not affected by the ejection pressure.
The following relations were obtained:
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The dendrite arm spacing varied from 0.6 to 2.8 μm. The mean cooling rate in the solidification temperature range was estimated at values between 103 and 5×104 K/s using the relation between the dendrite arm spacing and the cooling rate by R. Mehrabian. It could also be estimeted about 10 times higher by applying the relation by H. Matyja et al.View full abstractDownload PDF (2030K)
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