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Volume 45, Issue 11
Displaying 1-18 of 18 articles from this issue
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Shinichiro Omori, Yasuhiko Hashimoto, Koichiro Koyama1981 Volume 45 Issue 11 Pages 1107-1111
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to obtain the thermodynamic properties of Mo2B and Mo3Si, emf measurements of the cells with yttria-stabilized zirconia and calcia-stabilized zirconia as the electrolyte, ⟨Mo⟩ Mo, Mo2B, B2O3 |YSZ| air ⟨Pt⟩ and ⟨Mo⟩ Mo, Mo3Si, SiO2 |CSZ| Cr, Cr2O3 ⟨Mo⟩, were carried out. The standard free energy of formation of Mo2B, ΔG°Mo2B calculated from the emf values was expressed as ΔG°Mo2B=−112730+6.213T±1070 J/mol (1050–1400 K). The result was compared with those of other investigators. Values of the standard free energy of formation of Mo3Si, ΔG°Mo3Si, calculated from the emf values, were almost independent of the temperature in the range from about 1300 to 1400 K, and gave a mean value of −87700±1700 J/mol. The standard entropy of formation, ΔS°Mo3Si, could not be determined quantitatively, though it was most probable that it had a value close to zero.View full abstractDownload PDF (436K) -
Takasi Takezawa, Toru Yokoyama1981 Volume 45 Issue 11 Pages 1112-1118
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe lattice constants and the thermal expansions of Fe-Pd alloys have been measured. The volume of the 70 and 80 at%Pd alloys decrease at the order-disoder transition temperature on ordering, and the expansivity of these alloys decrease as the long-range order parameter increases. The volume decrease due to ferromagnetism of the 50∼80 at%Pd alloys occurs at the magnetic transition temperature in the ordered and disordered phases. The volume of these alloys at room temperature is smaller in the ordered phase than in the disordered phase. This is mainly attributed to the contraction due to ferromagnetism in the ordered phase.View full abstractDownload PDF (655K) -
Katsutoshi Ono, Hiroshi Tabuchi, Yukitomi Ueda, Joichiro Moriyama1981 Volume 45 Issue 11 Pages 1119-1125
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThermodynamic properties of the Nb-C-O system at high temperatures are important as fundamental knowledge on the carbothermic reduction of Nb2O5 in vacuum to produce niobium metal. Particularly, the vapor pressure data of the Nb-rich region in the Nb-C-O system are useful to evaluate the possibility of deoxidation by evaporation. In this investigation, the vapor species over the two-phase coexistence of Nb-NbO and NbO-NbO2 and the NbO2 phase were determined by means of the Knudsen cell-mass spectrometry combination method in the temperature range 1973–2173 K.
The Knudsen-effusion method was applied to measure the equilibrium vapor pressures of the gaseous niobium suboxides, NbO (g)+NbO2 (g) of the NbO phase and the equilibrium CO-pressure of the Nb-Nb2C-NbO three-phase field at 1773–2173 K. From these data, the standard free energy changes in the reactions
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\ oindentwere deduced from the measured vapor pressure data.View full abstractDownload PDF (489K) -
Toshio Oishi, Katsutoshi Ono, Joichiro Moriyama1981 Volume 45 Issue 11 Pages 1126-1129
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe standard free energy of formation of CoO (s) and the activity of cobalt in the liquid Cu-Co alloys were determined by means of the solid oxide galvanic cells as
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The standard free energy of formation of CoO (s) was found to be given by
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The activity of cobalt in the liquid Cu-Co alloys showed a large positive deviation from the Raoult’s law. The activity coefficient of cobalt at infinite dilution was also calculated.
Oxygen solubility in the liquid Cu-Co alloys in equilibrium with solid CoO at 1573 K was also obtained by the sampling and analysis and showed a minimum of about 0.025 mass% at 4–5 atom% cobalt.View full abstractDownload PDF (316K) -
Takashi Nakamura, Fumio Noguchi, Yasuaki Ueda1981 Volume 45 Issue 11 Pages 1130-1137
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe thermal decomposition of mercury sulfate (HgSO4, Hg2SO4) in air, Ar and SO2 was investigated by thermogravimetry and diffrential thermal analysis. The products at various stages of the decomposition were characterized by X-ray diffraction analysis, infrared absorption spectroscopy and photoelectron spectroscopy.
HgSO4 apparently vaporizes in one step but decomposes according to the following two reactions in air and Ar:
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\ oindentThe activation energy of equation (2) obtained by the kissinger method using D.T.A. was larger than that of equation (1). It is suggested that the equation (2) is a rate determining step of the decomposition of HgSO4. On the other hand, in an atmosphere containing SO2, HgSO4 decomposes at lower temperature than in air and Ar. The following equation (3) might reason the decomposing reaction of HgSO4 in SO2:
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Hg2SO4 in the first step decomposes to gaseous Hg and HgSO4, which continuously decomposes according to the above mentioned steps in each atmosphere.View full abstractDownload PDF (574K) -
Toshiya Harada, Toyonobu Yoshida, Toshihiko Koseki, Kazuo Akashi1981 Volume 45 Issue 11 Pages 1138-1145
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe co-condensation process of high temperature metallic vapors was examined in order to investigate the possibility of synthesizing ultrafine alloy particles from a vapor state. Experimental investigations were made for Nb-Al and Nb-Si systems by using an rf plasma evaporation method. Two kinds of metallic vapors in a plasma flame were quenched and deposited on a water-cooled copper surface. X-ray diffraction analysis of the prepared particles revealed the formation of some compounds, such as NbAl3 for Nb-Al system, and Nb5Si3 for Nb-Si system. Several theoretical investigations were also made for a better understanding of the process. One is about the quenching rate of the metallic vapors, which was estimated by the calculation of the flow patterns and temperature distributions in a quenching region. The second is about the nucleation temperatures of Nb, Al, and Si according to the Lothe-Pound theory. The third is about the particle growth history of Nb. The results showed that the quenching rate was 104–105 K/s and the nucleation temperatures were about 3000 K, 1500 K, and 2000 K for Nb, Al, and Si, respectively.
On the basis of the results of the experimental and theoretical investigations, the co-condensation process of high temperature metallic vapors was discussed. It was found that even if one component was condensed preferentially, composition-controlled alloy particles could be synthesized, provided that the other component began to condense while the former component particles were in a liquid state.View full abstractDownload PDF (765K) -
Hakaru Masumoto, Showhachi Sawaya, Masakatsu Hinai1981 Volume 45 Issue 11 Pages 1145-1150
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe internal friction Q−1, magnetic hysteresis loop, magnetostriction λ, ΔG effect and mechanical properties have been measured in Ni-Co alloys containing 0–70%Co. The Q−1 and regidity modulus measurements were carried out by the inverted tortion pendulum method. The hysteresis loop and λ were measured using an automatic recording fluxmeter and the optical roller method. Tensile testing was performed using an Instron-type tensile machine.
The Q−1 values of Ni-Co alloys increase with maximum shear strain-amplitude γm and attain their peaks Q−1max. For the alloys with Co less than 20%, the variation in Q−1max with composition is complex and Q−1max shows a maximum at 10%Co. For the alloys with Co more than 22%, Q−1max becomes higher by water-quenching than by furnace-cooling. In the range of 20–60%Co, the hysteresis loop after furnace-cooling is of the Perminvar-type, but the loop after water-quenching is normal. Furthermore, the variations in coercive force Hc with composition and heat-treatment are very similar to those in γc which is the γm value for Q−1max. The Hc value is proportional to the γc value. The strengths of magnetic field H for the maximum of Q−1max are almost consistent with those for the maximum values of ΔWh⁄ΔH and Δλ⁄ΔH which are gradients of the lines joining the origin to each point on the curves of hysteresis loss Wh or λ versus H.View full abstractDownload PDF (466K) -
Akira Chiba, Keitaro Fujita, Akihiko Sakuragi1981 Volume 45 Issue 11 Pages 1151-1160
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCarburizing of ferritic alloys containing substitutional solute such as Ti or V having a high affinity for carbon yields carbide-dispersed layer (CD layer) under a similar mechanism to the internal oxidation.
In this work, the kinetics of carbide-dispersion carburizing (CD carburizing) of Fe-Ti alloys containing up to 3.85 mass%Ti has been investigated at temperatures between 923 and 1023 K. A CD layer grows in proportion to the square root of time and the growth rate was explained by a kinetic equation proposed by Wagner for the internal oxidation. The carbide produced in a CD layer has been identified to be TiC by X-ray analysis, and the morphology of the carbide has been studied by electron microscopy. The particle size of carbide increased lineally with depth from the specimen surface. The hardness of a CD layer increased with increasing Ti content, and reached Hv 770 at about 3 mass%Ti. No further increase in hardness was observed in the alloys with higher Ti content, because the solubility of Ti in α-Fe was limited.View full abstractDownload PDF (1552K) -
Mutsumi Abe, Kenichiro Ouchi, Kazuhiko Asano, Akira Fujiwara1981 Volume 45 Issue 11 Pages 1161-1169
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSInitiation and propagation behavior of grain-boundary cracking in an Al-Zn-Mg alloy in various environments has been investigated in relation to the stress corrosion cracking.
The stress to initiate grain-boundary micro-cracks at the surface of specimen has been estimated from the stress at which the cracks are observed by an optical microscope. At stresses above the 0.2% proof stress, the cracks have been found to initiate mechanically, while below the 0.2% proof stress the cracks are initiated by the thermally activated process.
However, in both cases, the environment does not affect the initiation stress. The activation energies obtained were about 45 kJ/mol for hydrogen charged specimens and about 110 kJ/mol for non-charged specimens.
The influence of strain rates on mechanical properties in various environments has been examined in relation to the propagation process of grain-boundary cracking. The ultimate tensile strength and the elongation have been found to decrease with decreasing strain rate and particularly in corrosive atmospheres. From the analysis of the condition for plastic instability the growth rate of cracks has been found to increase in corrosive environments and at higher temperatures. In the propagation process, the thermally activated process is also involved with an energy of about 37 kJ/mol. The electrochemical polarization has been found to affect the propagation velocity of cracks in such a way that the anodic polarization increases the velocity. However, the activation process itself is not affected by the polarization.
These observations can be interpreted in terms of hydrogen embrittlement.View full abstractDownload PDF (916K) -
Setsuo Takaki, Youichi Tokunaga1981 Volume 45 Issue 11 Pages 1169-1175
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe aging reactions of ferritic and martensitic iron alloys containing 11–30%Cr and 0–10%Co, and 13%Cr maraging steel containing Co and Mo have been investigated by means of calorimetric analysis and hardness testing. The specific heat versus temperature curves of the high Cr ferritic and martensitic alloys are characterized by the appearance of an evolution peak due to the formation of Cr rich zones in the temperature range between 330 and 540°C, and also an absorption peak due to the reversion of them in the higher temperature range between 500 and 590°C. The amount of evolution increases with increasing content of not only Cr but also Co. This result shows that the addition of Co promotes the formation of Cr rich zones resulting in the so-called 475°C embrittlement.
In 13%Cr maraging steel, another evolution peak due to the precipitation of the intermetalic compound containing Mo appears in the higher temperature range between 520 and 660°C. On the low temperature aging in which the intermetalic compound never precipitates, however, the hardness increases more greatly than in the Mo free martensitic alloys. Thus, it is suggested that Mo as well as Cr forms the rich zones in the same temperature range between 330 and 540°C on the specific heat versus temperature curve. On the 500°C isothermal aging, for example, the Mo rich zones seem to be replaced by the intermetalic compound in the later stage of hardening. Lastly, the two evolution peaks and one absorption peak are separated on the specific heat versus temperature curve of as quenched 13%Cr maraging steel.View full abstractDownload PDF (598K) -
Hakaru Masumoto, Kiyoshi Watanabe1981 Volume 45 Issue 11 Pages 1176-1179
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMagnetic properties of Fe-Pd-Ag alloys containing 17∼47 at%Pd and 1∼30 at%Ag have been measured. The coercive force of the alloys increases with increasing silver content to 12%. The 59 at%Fe, 29 at%Pd and 12 at%Ag alloy tempered after water-quenching has a coercive force of 95.5 kA·m−1, a residual magnetic flux density of 1.04T and a maximum energy product of 43.0 kJ·m−3. Another alloy containing 58 at%Fe, 32 at%Pd and 10 at%Ag wire-drawn has a higher coercive force of 115.4 kA·m−1, a residual magnetic flux density of 0.90T and a maximum energy product of 41 kJ·m−3.
It is considered that the high coercivity of the alloy is due mainly to the high magneto-crystalline anisotropy of γ1 phase dispersed in α phase.View full abstractDownload PDF (272K) -
Tsugio Ogura, Akihiro Makino, Tsuyoshi Masumoto1981 Volume 45 Issue 11 Pages 1180-1186
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSExtensive applications of the grain boundary etching method (GEM) were made to a low alloy CrMo steel, an austenitic Fe-40%Ni alloy and an Fe-3%Si alloy by using an etching solution which had been confirmed to be valid for detecting P at grain boundaries of NiCr steels. The polarization characteristics of these steels and alloys in 0.5 kmol/m3 H2SO4 solution were also measured and compared with their GEM applicabilities.
The GEM was successfully applied to the CrMo steel. No grain boundaries in the Fe-Si alloy and only a few in the Fe-Ni alloy suffered selective etching attack, while prominent steps were found along their grain boundaries due to lack of and to difference in the chemical stabilities of grain interiors in the etching solution. The importance of surface stability in an etching solution for GEM applicability was thus suggested. The polarization curve of the CrMo steel was very akin to that of the NiCr steel and indicated that the surfaces of these steels were nobler electrochemically than those of the Fe-Ni and Fe-Si alloys. The addition of Cr to these alloys made their surfaces more stable and their polarization characteristics akin to that of the NiCr steel. As a result, their grain boundaries became sensitive to selective etching attack.
From these experimental results, it was concluded that any steels to which the present GEM is applicable should have surface stabilities similar to that of the NiCr steel, and that the measurement of polarization curve helps us assess the GEM applicability to given steels.View full abstractDownload PDF (1316K) -
Manabu Tanaka, Haruhiko Fujita1981 Volume 45 Issue 11 Pages 1187-1195
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCreep test has been performed at temperatures of 873 K and 973 K on an austenitic 21-4N steel with a large amount of M23C6 carbides as well as on a SUS 304 steel without any precipitates. Discussion was then made on the relation between internal stress in the steady-state creep obtained by the strain dip test with application of the extrapolation method and precipitate particles or the dislocation structure.
It was found that internal stress increased with an increase of applied stress in both steels, internal stress reached a constant value of 280 MPa at 873 K in the 21-4N steel. This value is close to the Orowan stress at 873 K (σo\fallingdotseq2Gb⁄L0=312 MPa, L0: free spacing between particles). By means of transmission electron microscopy to thin films, unlike in the SUS 304 steel, the cell structure was not formed during the steady-state creep in the 21-4N steel, but the dislocation density around precipitates increased with an increase of applied stress. It was considered from calculations in this study that internal stress in both steels is a long-range force acting on mobile dislocations when they surmount particles by the Orowan mechanism or pass through regions of the high-dislocation density around particles or cell boundaries.
The activation energy of creep was 291±8 kJ/mol for the 21-4N steel and 297±19 kJ/mol for the SUS 304 steel, independent of applied stress and temperature. These values were almost equal to that of self-diffusion in gamma iron. An activation area which was of the same order as lb (l: dislocation spacing in a region of the high-dislocation density around particles or at cell boundaries) decreased with an increase of applied stress in both the steels.View full abstractDownload PDF (736K) -
Hao Shi Ming, Takemori Takayama, Taiji Nishizawa1981 Volume 45 Issue 11 Pages 1195-1201
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCarburizing of a 12%Cr steel containing 0.1–0.9%Si was performed at 950°C, and the microstructure, the hardness and the wear resistance of the carburized and hardened layer were examined. Addition of Si was effective to eliminate the formation of massive carbides in the outer region and also of boundary carbides in the intermediate region. It was revealed that fine dispersion of Cr7C3 carbides occurred throughout the carburized layer. The radius and amount of the carbides in the surface region were about 0.25 μm and 30% by volume, respectively. The carburized and hardened layer with such fine dispersion of Cr7C3 was much superior in the hardness as well as the wear resistance to the ordinary high chromium tool steel.View full abstractDownload PDF (1195K) -
Yoshiharu Waku, Tsuyoshi Masumoto1981 Volume 45 Issue 11 Pages 1202-1207
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn the present work the deformation and fracture at the crack tip were examined using Ni78Si10B12 amorphous thin plates about 21.7 mm in width and 0.027 mm in thickness which were prepared by a single roller quenching apparatus.
As the plastic zone became larger with increase of the applied stress, the crack tip opening displacement increased. From the growth behavior of the plastic zone and the relation between the crack tip opening displacement and the applied stress, it was found that the transition from a mixed state of plane stress and plane strain to a plane stress state occurred in the early stage of plastic deformation at the crack tip, and therefore that a greater part of plastic deformation and fracture occurred in the plane stress state.
The relation between the size of plastic zone and the applied stress and the relation between the crack tip opening displacement and the applied stress agree very well with the theoretical curves calculated using the B-C-S theory. The fracture of specimen occurred when the size of plastic zone, the crack tip opening displacement or the stress intensity factor reached a critical value. The experimental relationship between the fracture stress and the crack length was explained by the B-C-S theory.View full abstractDownload PDF (802K) -
Yoshisada Ueda, Seiji Kunimitsu, Naotaka Kondo1981 Volume 45 Issue 11 Pages 1208-1214
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSStrengthening of sintered Fe by means of Cu-infiltration and Al2O3 dispersion was investigated. Fe powder and Fe-Al2O3 powder-mixture were compacted at pressures in the range from 98 to 296 MPa and these sintered compacts with different sizes and distributions of pores were infiltrated with molten Cu. A compression test of the Cu-infiltrated Fe and Fe-Al2O3 was also conducted. The amount of Cu infiltrated into the sintered Fe increased with increasing infiltration-temperature, but was independent of the size and distribution of pores. The mean infiltration depth was proportional to the amount of Cu infiltrated. The lightly compacted Fe was not fully infiltrated and the residual pores were observed in the Cu-infiltrated layer. Addition of Al2O3 (≤0.3 μm) up to 4 vol% had no effect on the amount of Cu infiltrated, but by adding of 6 vol%Al2O3, the amount of the infiltrated Cu decreased slightly. The Al2O3 dispersoids were located on the boundaries of Fe particles in the compact and formed networks. The flow stress in the compression test was, therefore, lowered with increasing Al2O3 volume fraction.
The Cu-infiltrated Fe-2 vol%Al2O3 compact, in which a fairly uniform distribution of Al2O3 dispersoids was observed, surpassed the Cu-infiltrated Fe compact in the flow stress. This is due to the dispersion-strengthening of the Cu phase by Al2O3 dispersoids. However, the flow stresses of the Cu-infiltrated Fe-4 vol% and Fe-6 vol%Al2O3 compacts having non-uniform distribution of Al2O3 were lower than that of the Cu-infiltrated Fe compact.View full abstractDownload PDF (821K) -
Tetsuichi Motegi, Atsumi Ohno1981 Volume 45 Issue 11 Pages 1215-1220
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe formation mechanisms in the macrosegregation of some Sn-Bi and Bi-Sn alloy ingots with equiaxed or angular crystal zones were studied using the unidirectional solidification technique. The solidification phenomena during horizontal unidirectional cooling were observed directly on the molten surface. The solute concentration was determined at various points in each ingot.
In Sn base Bi alloys, the formation and the separation of granular crystals on the cooling end were recognized at the initial stage of solidification. Separate crystals moved toward the hotter zone, and formed an equiaxed zone there. Then columnar dendrites grew from the cooling end and extended to the equiaxed zone. The columnar dendrite zone showed a normal segregation, but the equiaxed zone showed a negative segregation.
In Bi base Sn alloys, angular primary crystals floated up to the molten surface at a great distance from the cooling end, and then these crystals moved to the cooling end by thermal convection and were trapped there. Equiaxed eutectic grains were formed at the last stage of solidification. The solute concentration in these alloys was low near the cooling end and high at the equiaxed eutectic zone. These ingots showed a normal segregation.View full abstractDownload PDF (882K) -
Toshitada Shimozaki, Masami Onishi1981 Volume 45 Issue 11 Pages 1221-1222
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (219K)
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