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Volume 46, Issue 11
Displaying 1-12 of 12 articles from this issue
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Mineo Kogachi1982 Volume 46 Issue 11 Pages 1037-1041
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSStability of the L10-type ordered phase appearing in the Cu1−cAuc alloy system near the composition of c=1⁄2 is studied by the use of pseudopotential treatment which is a conventional method extended previously by the author to the noble-simple or noble-noble metal alloy systems. The structure-dependent energy U is conveniently composed of three terms; the energy of conduction electrons within an alloy crystal field (Uel), the electrostatic energy of ions occupying lattice sites (Ues) and the repulsive energy of ions due to overlap of d-electrons (Urp).
The ordering energy of L10-type ordered phase is calculated for various c’s, and the energy change in U due to the tetragonal distortion for the CuAu alloy is obtained as a function of the axial ratio x. Numerical results for the ordering energy show negative values in the composition range 0.4≤c≤0.6 and explain successfully the fact that the ordered phase with L10-type exists at a low temperature as a stable phase. An estimation of the transition temperature gives a value of 1060 K for the CuAu alloy which is higher than the observed one (658 K). On the other hand, for the CuAu alloy, energy U calculated as a function of x has a minimum at x\simeq0.60, which is far from the observation (x=0.926), although it shows another minimum at x\simeq0.90.View full abstractDownload PDF (402K) -
Hisashi Furuya, Yoshimi Tanabe1982 Volume 46 Issue 11 Pages 1042-1048
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis report describes the corrosion resistance of electrodeposited amorphous chromium and amorphous binary chromium alloys. The structure of electrodeposited chromium became crystalline or amorphous according to the condition of electrodeposition. Amorphous binary chromium alloys—Cr-W, Cr-Mo, and Cr-Fe—were obtained from the baths for amorphous chromium deposition in which W, Mo, or Fe ions were added. First, the corrosion resistance of amorphous chromium was compared with that of crystalline chromium to investigate the effect of the structure of electro-deposited chromium on the corrosion resistance. Then, the corrosion resistance of amorphous binary chromium alloys were compared with that of amorphous chromium to investigate the influence of alloying elements on the corrosion resistance. The corrosion resistance was examined by the electrochemical method. Anodic polarization curves were measured by the potentiodynamic method with the potential sweep rate of 2.0×10−3 V/s in 1 kmol/m3 HCl and 1 kmol/m3 H2SO4 in air at room temperature. The polarization curves showed that crystalline chromium was passivated only by anodic polarization, whereas amorphous chromium and binary chromium alloys were passivated spontaneously in the solutions. Accordingly, the corrosion resistance of electrodeposited chromium was improved remarkably by the structure change from a crystalline state to an amorphous state. Furthermore, the corrosion resistance of the amorphous binary chromium alloys was superior to that of amorphous chromium.View full abstractDownload PDF (690K) -
Kazumi Ogino, Hitoshi Taimatsu, Fumitada Nakatani1982 Volume 46 Issue 11 Pages 1049-1054
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSurface tensions of liquid Fe-Ni, Fe-Co and Ni-Co binary alloys and contact angles between these alloys and Al2O3 substrates were measured in an atmosphere of purified hydrogen by the sessile drop method. Measured surface tensions of these alloys varied almost linearly with the alloy composition.
The wettability of Al2O3 by liquid alloys increased drastically with an increase in Ni content in Fe-Ni and Ni-Co alloys, and increased proportionally with an increase in Co content in Fe-Co alloys. Uneveness of the interfaces between solidified alloys and Al2O3 substrates was observed with an increase in the wettability, especially in Fe-Ni and Ni-Co alloys. This phenomenon can be explained on the basis of the thermodynamical consideration on the dissociation of Al2O3 in contact with the liquid alloys.View full abstractDownload PDF (505K) -
Kazuichi Mizoguchi, Kazunori Okamoto, Yukio Suginohara1982 Volume 46 Issue 11 Pages 1055-1060
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn a previous paper, the existence of octahedral coordinate Al3+ ion in the range of molar ratio of Al2O3/MO<1 was inferred from the effect of Al2O3 on the viscosities of Na2O, PbO, CaO and MnO silicate melts. In the present study, the viscosities of K2O, Li2O, BaO, ZnO, SrO and MgO systems were measured in order to confirm the previous result, and the viscosity data of each alumino-silicate melt were arranged using a parameter P corresponding to the ratio, nO−⁄nSi, in the binary silicate.
The parameter P is expressed by
(This article is not displayable. Please see full text pdf.)
\ oindentwhere ZM is the electric charge of M ion, and nM, nSi and nAl are the ion fractions, and X is the ratio of the number of tetrahedral coordinate Al3+ ions to that of the total Al3+ ions.
Satisfactory results were obtained by the arrangement described above, and calculated values of X were 0.95(K2O), 0.90(Na2O, BaO), 0.78(SrO), 0.74(PbO), 0.73(Li2O, CaO), 0.60(MnO), 0.51(MgO) and 0.50(ZnO). Plot of X against the polarizing power Z⁄ri2 was linear, and X decreased with the basicity of MO.View full abstractDownload PDF (454K) -
Motonori Eguchi, Abdul Khalique, Hiroyuki Nakamura1982 Volume 46 Issue 11 Pages 1061-1067
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to obtain fandamental information on the application to a new zinc extraction process which does not produce sulfur dioxide, the dissolution kinetics of sized sphalerite in sulfuric acid solution was studied under a non-oxidative condition. The apparent linear dissolution rate which was independent of the particle size of sample was obtained from the experimental dissolution curves. The effects of iron content of sphalerite, liquid composition and other factors on this dissolution rate in sulfuric acid solution were examined. To get information on the accelerator for the sulfuric acid leaching, the effect of the addition of chloride ion was also examined. From the experimental results and the thermodynamical consideration for the Zn-Cl-H2O solution equilibria, a possible reaction mechanism was presented.
The dissolution rate of sphalerite in sulfuric acid solution increased with the increase in iron content of sphalerite, acid concentration or temperature, but was depressed by zinc ion in solution. The dissolution rate was not affected by other factors. It was estimated that the rate controlling process was the surface reaction of ZnS with hydrogen ion and that zinc ion in the solution took part in this process as a surface potential determining ion.
Under the coexistence of chloride and zinc ions in solution, the dissolution rate of sphalerite increased considerably in a region of high chloride/zinc ratio at which anionic zinc chloride complexes became dominant thermodynamically, while in the low ratio at which cationic species were dominant, the rate was slow. The dissolution behavior at a high chloride/zinc ratio revealed in another experiment suggested that the rate controlling process was a reaction of solid surface with hydrogen ion. A reaction process similar to that in a plain sulfuric acid solution was presumed for the chloride containing system with the postulation that the adsorbed species on solid surface were anionic complexes at a high chloride/zinc ratio.View full abstractDownload PDF (575K) -
Zhong da Yin, Yasuji Kataura, Hajime Suto1982 Volume 46 Issue 11 Pages 1068-1073
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to improve the fatigue strength of a 3.5 GPa grade maraging steel (8%Ni-20%Co-14%Mo-Fe), the alloys were melted carefully in CaO-lining crucibles with basic flux (CaO:CaF2:Al2O3=6:3:1) and were deoxidized with Mn, Si, Al, Ti and Ca individually or compositely. These alloys subjected to thermomechanical treatments were fatigue-tested with a one-side tension machine, and inclusions in these alloys were analysed metallographically. Results obtained are as follows: (1) As compared with a conventionally vacuum-melted alloy in an Al2O3 crucible, the alloys melted in basic atmosphere as mentioned above showed superior fatigue strength, and the size, number and mass pct. of inclusions were decreased distinctly. (2) The endurance limit of the alloys deoxidized with Al and Ti compositely was 2.3 GPa. This value may be almost the limiting value expected for 3.5 GPa grade steels. (3) The workability of the alloys deoxidized with Al and Ca compositely was very superior. The tensile strength of this drawn and aged wire 0.2 mm in diameter was 4.3 GPa.View full abstractDownload PDF (566K) -
Motoaki Osawa1982 Volume 46 Issue 11 Pages 1074-1080
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe mechanism of the degradation of corrosion for deformed Type 304 steel exposed to 28 MPa hydrogen at 673 K for 57.6 ks has been investigated by electrochemical measurements. The anodic polarization curve of hydrogen-charged martensitic Type 304 steel in H2SO4 solution shows three anodic peaks at the potentials of −0.4, −0.3 and −0.05 V vs. SCE, whereas that of hydrogen-charged austenitic steel does the peaks at −0.3 and −0.05 V vs. SCE, but not the peak at −0.4 V vs. SCE. Severe corrosion was observed on the hydrogen-charged martensitic steel when it was held at −0.4 V vs. SCE in H2SO4 solution. This severe corrosion was prevented by heating the steel at 923 K, although it was not avoided up to 873 K. It was found that the cathodically hydrogen-charging at ambient temperature induced martensite phases in the austenitic steel, and it did a hydride phase at 373 K. The anodic polarization curve of Type 304 steel containing a hydride phase revealed an anodic peak at −0.5 V vs. SCE, while that of the steel containing hydrogen-induced martensite phase did not produce the peak at −0.4 V vs. SCE. Consequently, the degradation of corrosion of deformed and hydrogen absorbed Type 304 steel can be ascribed to the selective corrosion of hydride in martensite phases by deformation.View full abstractDownload PDF (714K) -
Yukiteru Asayama1982 Volume 46 Issue 11 Pages 1081-1088
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBehaviors of delayed failure in an air environment were investigated in ultra-high strength 18%Ni maraging steels. The slow crack growth velocity caused by delayed failure increases with aging time in an early stage of aging, and after reaching a maximum, it decreases inversely with aging time. The aging time for the slow crack growth velocity to reach a maximum becomes shorter with increasing aging temperature.
The delayed failure does not occur in vacuum environment, and therefore, it is assumed that the delayed failure is controlled by diffusion associated with stress-induced migration of hydrogen produced by decomposition of water adsorbed by the surface of the steel. The slow crack growth velocity of the delayed failure depends on the catalistic action of steels changing by the aging condition which results in the decomposition of water.
The aging time for the slow crack growth velocity to reach a maximum at a respective aging temperature is independent of the composition of the steels and only dependent on the aging temperature, but the slow crack growth velocity depends on the chemical composition of the steels. Co and Ti have a large effect on the slow crack growth velocity, but Mo has little effect.
It is considered that the behavior of the delayed failure is controlled by the formation and decomposition of Ni3Ti(DO3) which probably promotes the decomposition of water.View full abstractDownload PDF (861K) -
Yoshinobu Sato, Takeshi Takeyama1982 Volume 46 Issue 11 Pages 1089-1094
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe suitability of a 6%V permalloy for magnetic head materials used in a digital tape recording equipment of an electronic computer was investigated in comparison with high permeability permalloys commonly used, e.g., 4%Mo-5%Cu permalloy and 4%Mo permalloy.
Measurements of dc magnetic properties, ac magnetic permeabilities at H=0.4 A/m (frequency range 1-300 kHz) and its stress-sensitivity, e.g., the change in effective permeability caused by application of the compressive stress 1 MPa perpendicular to the sheet surfaces, were carried out for these permalloys 0.1, 0.05 and 0.025 mm in sheet thickness, subjected to various heat treatments. Wear tests were carried out by rubbing the test specimens of these permalloys against a γ-Fe2O3 magnetic tape at the running speed of 3 m/s. The saturation magnetostriction, the electrical resistivity and the mechanical hardness were also measured.
Results obtained are summarized as follows:
(1) The V permalloy examined has a better ac magnetic permeability at a high frequency range as well as a better dc magnetic properties than the compared alloys, and in particular its magnetic properties at low annealing temperatures below 1173 K are characteristically superior to those of the familiar high permeability permalloys.
(2) The stress-sensitivity in the magnetic properties of the V permalloy is much smaller than that of the compared alloys at any examined annealing temperatures and exciting frequencies, so that values of permeabilities under the compressive stress remain very high.
(3) Thin oxide films are formed on the contact surface of the V permalloy specimen during rubbing against the γ-Fe2O3 magnetic tape at high speed, and this formation brings about the wear-resistance property superior to that of the compared alloys.
(4) The V permalloy has the same degree of mechanical hardness as other technical soft permalloys, and hence has a good workability.
(5) From these results, the 6%V permalloy is an excellent and favourable alloy as a magnetic head material.View full abstractDownload PDF (535K) -
Itsuo Ohnaka, Tatsuichi Fukusako, Hiroaki Tsutsumi1982 Volume 46 Issue 11 Pages 1095-1102
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA new atomization process for metal powders is presented, in which molten metal is ejected into water layer formed on a rotating drum inner surface by the centrifugal force and atomized by the rotating water. Atomization trials were made using an Fe40Ni40B20 alloy. A mean particle size of the powder obtained decreased with increasing rotational speed of the drum and with decreasing nozzle diameter. The quench rate for particles less than about 100 μm in diameter was estimated to range from 105 to 106 K/s, and spherical amorphous powder was obtained. This process may be useful for producing rapidly quenched metallic powders because of its high quench rate, uniform size and spherical shape of powders produced, high powder yield and no scattering of particles.View full abstractDownload PDF (1001K) -
Ken-ichi Miyazawa, Takao Choh, Michio Inouye1982 Volume 46 Issue 11 Pages 1102-1108
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe microscopic solidification structure of Pb-Sb eutectic alloy ribbons prepared by the twin-roll rapid solidification process has been examined to understand cooling characteristics of the process. The result shows that the average size and the area ratio of globular structure mainly consisting of Sb have the minimum for a certain roll rotation speed and decrease with decreasing initial roll gap. The effect of melt flow rate on the structure has not been detected under the adopted experimental conditions.
Regarding the relationship between the solidification structure and the cooling rate of melt, a preliminary experiment of the rapid quenching from melt has revealed that with increasing cooling rate the structure consisting of Sb phase becomes globular and the average size decreases.
Furthermore, velocity and temperature fields of the process were estimated using a mathematical model to discuss effects of key process parameters on cooling rates of the rapidly solidified metallic ribbons. The estimated results show that under the adopted experimental conditions the mean cooling rate in the melt region between rolls has a maximum for a certain roll rotation speed and increases with decreasing initial roll gap. These theoretical predictions qualitatively agree with results obtained from the observed solidification structure.View full abstractDownload PDF (926K) -
Ichiro Fukumoto, Shogo Tomita, Yuichi Suzuki1982 Volume 46 Issue 11 Pages 1109-1110
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (155K)
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