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Volume 45, Issue 10
Displaying 1-17 of 17 articles from this issue
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Tsuyoshi Yamamoto, Toshiyuki Takashima, Keizo Nishida1981 Volume 45 Issue 10 Pages 985-990
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFor the purpose of studying interdiffusion in the α-solid solution of the Fe-Sn system, experiments were performed using the method of vapor-solid couple at temperatures between 1073 and 1373 K. As a vapor source, fine powder of a 40 mass%(23.9 at%)Sn-Fe alloy was used. The surface concentration of Sn in diffusion-annealed test pieces almost coincided with the solubility limits reported in the Fe-Sn phase diagram at 1173–1373 K, while significant deviations in the solubility limits were found at 1073 K and 1123 K. Fine alumina markers placed on the test pieces prior to diffusion remained on the surface after annealing. Each penetration curve at temperatures between 1073 and 1173 K was similar to the error function curve for a particular \Tilde{D} value.
The value of \Tilde{D} showed a relatively small dependence upon the Sn concentration at each temperature. The activation energies for interdiffusion, \Tilde{Q}, decreased from 228 to 221 kJ/mol with increasing Sn concentration. The impurity diffusion coefficients of Sn in Fe, DSn*, between 1073 and 1173 K were obtained from extrapolation of \Tilde{D} to 0 at%Sn and its activation energy, QSn*, was evaluated to be 229 kJ/mol. The relationship between the entropy term, \Tilde{D}0, and \Tilde{Q} is represented by the following equation:
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Jirô Watanabé, Yuji Imashimizu1981 Volume 45 Issue 10 Pages 990-996
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESS[321] single crystals of copper and 0.05, 0.10, 0.20, 1.0, 2.0 and 5.0 at%Al-Cu alloys were grown with a subboundary-free seed, using the Bridgman method, at a rate of furnace travel 8.3×10−6 m·s−1 in an enclosed purified argon gas, and the distribution and density of dislocations were investigated by the etch pit technique. In copper crystals, dislocations were always arranged into a network of subboundaries and distributed randomly within subgrains with an overall density of dislocations 1.6×10−9–7.0×10−9 m−2. On the other hand, the dislocation structure in copper crystals was observed to vary markedly with a little addition of aluminium. Subboundary-free crystals with a low dislocation density, about one order less than that of copper crystals, were grown, though some defective ones which contained a few kinds of subboundaries were also produced. The probability of growth of the subboundary-free crystals was highest for the 0.05 at%Al and decreased at the higher aluminium content, while the degree of crystal perfection was highest for 0.10 at%Al. In contrast to the network pattern of subboundaries in copper crystals, the subboundaries in crystals of the low aluminium content tended to elongate straight along certain crystallographic directions, and those in crystals of the high aluminium content preferred to follow the growth direction. Moreover, it was found that a rosette pattern of dislocations and the one like this formed in all alloy crystals and elongated dislocation clusters running along the growth direction formed in crystals of the high aluminium content. These effects of aluminium were discussed on the basis of some concepts of dislocation nucleation due to solute atoms in melt-grown crystals.View full abstractDownload PDF (1284K) -
Shigeo Sugawara, Jirô Watanabé1981 Volume 45 Issue 10 Pages 996-1002
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe (111) surfaces of copper crystals rapidly-cooled from 1273 K in a purified Ar atmosphere were etched in three kinds of dislocation etchants, and the etch patterns were studied by means of optical and electron microscopies. From the replica examinations with an optical microscope dark and deep etch pits with beaks were found in addition to the normal dislocation etch pits. Their densities amounted to 107–108 m−2, two orders of magnitude less than those of the normal ones. When the crystal was etched for a long period, the etch pits with beaks gradually changed from sharply-pointed and deep ones to flat-bottomed and shallow ones, and finally disappeared, while small ones newly appeared at some other places. It is noted that such etch pits cannot be observed in copper crystals slowly-cooled from the same temperature in Ar atmosphere. Detailed observations of the replicas with an electron microscope revealed that the beaks extended into the inside of the crystal from the apex of the etch pits along the oblique [110] (otherwise [101] or [011]) direction though details of their shapes varied with changing etching solution. Defect ribbons with a some-what complicated structure were observed in thin films obtained from the rapidly-cooled copper crystal, which might presumably be associated with the etch beaks.View full abstractDownload PDF (1834K) -
Toshiyuki Aida, Sadanori Taguchi, Isamu Yuito, Shigehiko Yamamoto, Aki ...1981 Volume 45 Issue 10 Pages 1003-1012
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSProducts formed on the interface between a thermionic emissive material (Ba0.56Sr0.40Ca0.04)CO3 powder and a Ni-28 mass%W-0.4 mass%Zr metal plate were examined by X-ray diffraction method, the scanning electron microscopy and the EPMA analysis. The reaction was performed under the condition of 1073 K∼1373 K and 1.8 ks∼36 ks. The results are as follows.
(1) At the early stage of the reaction, Ba3WO6 was formed remarkably on the metal surface. The formation of Ba3WO6 was greatly enhanced by the oxidation of the metal due to CO2 gas produced at the time of BaCO3 decomposition. The Ba3WO6 has the same needle like shape as a starting material of the carbonate. The Ba3WO6 seems to be formed by the following solid-vapor reaction.
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(2) As the reaction proceeded, Ba3WO6 began to decrease and BaZrO3 gradually increased. The BaZrO3 was formed along the grain boundary inside the metal. The rate of the formation was found to be controlled by a diffusion process. The BaZrO3 seems to be formed by the following reaction.
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\ oindentwhere the W component is alloyed with the metal and remains as small particles on the metal surface.View full abstractDownload PDF (903K) -
Toshiyuki Aida, Sadanori Taguchi, Yukio Honda, Shigehiko Yamamoto, Hir ...1981 Volume 45 Issue 10 Pages 1013-1021
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSChemical reaction products formed on the interface between a thermionic emissive material (Ba0.56Sr0.40Ca0.04)CO3 and a base metal Ni-28 mass%W-0.4 mass%Zr were examined.
The results are as follows.
(1) In the case of a Ni-28W base metal, Ba3WO6 forms remarkably, at the early stage of the reaction, on the metal and increases with the succeeding reduction reaction of BaO by W. The initial Ba3WO6 production is greatly enhanced by the oxidation of the base metal due to CO2 gas preduced during heating procedure. This Ba3WO6 is produced by two ways, that are the reaction between BaWO4 and BaO, and the one between BaO and WO3. Coating of the metal with a Pt film is an effective method to suppress extra Ba3WO6 produced by the base metal oxidation.
(2) In the case of Ni-28W-0.4Zr, the amount of Ba3WO6 formed at the early stage decreases gradually and BaZrO3 begins to grow. As the reaction proceeds, BaZrO3 forms along grain boundaries inside the metal. Therefore, the production rate is affected by the grain size, and lowered in the case of the base metal with large grain size.
(3) Some thermodynamic consideration was made on the production of BaWO4, Ba3WO6 and BaZrO3. Preference of the reduction reaction of BaO by Zr or by W is determined by the free Ba production rate. The reaction with the highest Ba vaporization rate was found to predominate over many other possible reactions.View full abstractDownload PDF (825K) -
Katsutoshi Ono, Toshio Oishi, Joichiro Moriyama1981 Volume 45 Issue 10 Pages 1022-1029
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEMF measurements on galvanic cells involving solid-sulphide electrolytes may yield valuable sulphur potential data of metal-sulphur systems. CaS-2 mass%ZrS2 solid solution was expected to satisfy the conditions as solid electrolyte.
The EMF measurements on the cells [(I)] Mo (s)+Mo2S3 (s)/Sulphide electrolyte/Cu (l)+Cu-S (l) [(II)] W (s)+WS2 (s)/Sulphide electrolyte/Cu (l)+Cu-S (l) [(III)] Mo (s)+Mo2S3 (s)/Sulphide electrolyte/Fe (s)+Fe-S (l) [(IV)] W (s)+WS2 (s)/Sulphide electrolyte/Fe (s)+Fe-S (l) [(V)] Mo (s)+Mo2S3 (s)/Sulphide electrolyte/Ni (s)+Ni-S (l) [(VI)] W (s)+WS2 (s)/Sulphide electrolyte/Ni (s)+Ni-S (l) [(VII)] Mo (s)+Mo2S3 (s)/Sulphide electrolyte/Co (s)+Co-S (l) [(VIII)] W (s)+WS2 (s)/Sulphide electrolyte/Co (s)+Co-S (l) [(IX)] Mo (s)+Mo2S3 (s)/Sulphide electrolyte/Cr (s)+CrS (s) [(X)] W (s)+WS2 (s)/Sulphide electrolyte/Cr (s)+CrS (s) have been performed in the temperature range between 1250 and 1573 K. The obtained sulphur partial pressures of the metal-sulphide systems were compared with those from the H2-H2S gas equilibrium investigations.View full abstractDownload PDF (520K) -
Yasuo Uchiyama, Hideto Koga, Imao Tamura1981 Volume 45 Issue 10 Pages 1030-1035
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo study the effect of Fe3C on the reaction between solid iron and liquid zinc, carburized iron with abnormal structure was immersed into pure molten zinc for 600 s at 733 K and 773 K. Structures of an alloy layer and an alloy layer/iron base interface were observed, and X-ray intensity profiles of Fe and Zn were measured. Results obtained are as follows:
(1) The type of the alloy layer formed on carburized iron is the same as that formed on pure iron under the same condition. Fe3C projections are found at the alloy layer/iron base interface and Fe3ZnC particles are found in the alloy layer.
(2) At 733 K, the alloy layer structure near the Fe3C projection does not differ from that in the region where the Fe3C projection is absent. At 773 K, on the other hand, these two structures are different from each other, and a thick (δ1+η) layer with a fan-shaped outburst structure is formed near the Fe3C projection.
(3) The reaction between iron and zinc proceeds almost uniformly at 733 K, but at 773 K it proceeds faster at the pearlite zone than at the ferrite zone, and it also proceeds faster at the alloy layer/iron base interface at both temperatures.
(4) Fe3C projection at the interface reacts with zinc at the top, and breaks into particles in the alloy layer as the alloy layer grows.View full abstractDownload PDF (1367K) -
Yoshio Ohta, Akira Miyanaga, Ken-ji Morinaga, Tsutomu Yanagase1981 Volume 45 Issue 10 Pages 1036-1043
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSVarious factors that have a great effect on measurements of the electrical conductivity of ionic solutions and melts have been discussed theoretically and experimentally. From the discussion, the conventional method used for measurements of the electrical conductivity has been improved, so that it may be possible to measure the electrical conductivity of ionic solutions and melts absolutely, that is, without any cell constant.View full abstractDownload PDF (547K) -
Kenzo Kon, Shigeo Tsujikawa, Yoshihiro Hisamatsu1981 Volume 45 Issue 10 Pages 1043-1048
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe characteristics of stress corrosion cracking (SCC) of type 310 S steel single crystal were investigated in H2SO4-NaCl solution with reference to faceting dissolution and a crystallographic plane of the fracture surface in the two potential zones: I (near the corrosion potential) and II (active-passive transition region). Kinds of facets change in the order of {100}→{100}+{111}→{111} in 2.5 kmol/m3-H2SO4+0.2 kmol/m3-NaCl and 2.5 kmol/m3-H2SO4+0.5 kmol/m3-NaCl solutions, and change in the order of {100}→{110}→{111} in 2.5 kmol/m3-H2SO4+0.8 kmol/m3-NaCl solution with an increase in potential from the corrosion potential to the active-passive transition potential. There are many cracks on the {100} specimen surface at the potential of {100} faceting dissolution, and are many cracks on the {110} specimen surface at the potential of {110} faceting dissolution compared with other crystallographic planes. Cracking occurs as the result of a competition process between the dissolution rate on the surface (Ih) and the crack growth rate (\Dot{C}), and the upper critical potential corresponds to a potential to give a relation, Ih\simeq\Dot{C}. At the potentials of zone I in every solution, a crystallographic plane {hkl} of the fracture surface corresponds to the slowest dissolution plane {hkl} under every given condition. On the other hand, at the potentials of zone II {111} faceting dissolution occurs over all specimen surfaces. These results imply an important relationship between SCC and {hkl} faceting dissolution.View full abstractDownload PDF (1014K) -
Yoshiichi Sakamoto, Narutoshi Tabaru1981 Volume 45 Issue 10 Pages 1048-1055
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe temperature dependences of the diffusion coefficient and solubility of hydrogen in annealed and cold rolled Pd under different cathodic current densities have been measured over the temperature range from 279 to 335 K by means of the electrochemical permeation method.
The experimental permeation transients obtained by the galvanostatic charging method for both Pd specimens were fitted better to the theoretical transient derived under a constant hydrogen concentration directly beneath the cathodic surface than to the theoretical curve obtained under a constant hydrogen flux charged at the cathodic surface, regardless of the cathodic current densities and temperatures.
The activation energy for hydrogen diffusion in both Pd specimens did not depend upon the hydrogen concentration beneath the cathodic surface. The energy value for annealed Pd was ΔHD=21.48±1.41 kJ·mol−1. The activation energy for the cold rolled Pd was slightly larger than that for the annealed one. However, the diffusion coefficient of hydrogen in the as cold rolled Pd was lower than that in the annealed one and increased with the hydrogen concentration. The hydrogen concentration dependence of diffusivity in the cold rolled Pd is not explained by the thermodynamic factor based on the chemical potential gradient of hydrogen for the driving force of diffusion. On the other hand, the heat of solution of hydrogen in the annealed Pd was ΔHC=−17.03±1.21 kJ·mol−1, and the pre-exponential factor increased with the cathodic current density. The cold rolling brings about not only an increase in the solubility of hydrogen but also reduces slightly the heat of solution in a more exothermic sense.
The hydrogen permeation current efficiency showed the maximum at ic=5.0∼10 A·m−2 for both Pd specimens and increased with increasing temperature under the same ic values.View full abstractDownload PDF (643K) -
Motoaki Osawa1981 Volume 45 Issue 10 Pages 1056-1062
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffect of hydrogenation on the stress corrosion cracking (SCC) was studied in boiling 45%MgCl2 solution. Hydrogenation was carried out in 28 MPa hydrogen at 673 K for 57.6 ks (16 h). Little change in SCC susceptibility with hydrogenation was observed in solution treated Type 304 steel, but pre-stress in the range of 200–400 MPa produced an increase in SCC susceptibility with hydrogenation. Similar tendency was observed by charging with hydrogen through immersion in 5%HF-30%HNO3 solution or 0.5 kmol/m3 H2SO4 solution, as well as in boiling 45%MgCl2 solution containing 25 g/m3 NaAsO2. A corrosion rate of hydrogenated steel was greater than that of hydrogen-free one in boiling 45%MgCl2 solution, and selective corrosion of martensite was observed in a cold worked specimen containing hydrogen. It is considered from these results that the increase in SCC susceptibility of Type 304 steel with hydrogenation might be produced by selective corrosion of martensite.View full abstractDownload PDF (1020K) -
Shinzo Yano, Shotaro Morozumi, Shigeyasu Koda1981 Volume 45 Issue 10 Pages 1063-1070
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMolybdenum alloys containing up to 2.5 mass%Zr were nitrided in a purified nitrogen (0.1 MPa) at 1473–1823 K. The hardness of the nitrided layer increased, with increasing zirconium content and decreasing treatment temperature, to the maximum value of 1400 VPN.
In specimens nitrided below 1573 K, coherent disc-shaped precipitates ∼10 nm in diameter and ∼0.5 nm in thickness were revealed by electron microscopy to form on {100}Mo planes, giving rise to continuous streaking in ⟨100⟩Mo directions in the electron diffraction patterns. After nitriding above 1673 K, semi-coherent ZrN plates were observed to precipitate with the following orientation relationship: {100}ZrN\varparallel{100}Mo and ⟨100⟩ZrN\varparallel⟨100⟩Mo.
Neither preferential precipitation nor denuded zone existed along grain boundaries, but the ZrN particle size was appreciably larger near boundaries than in places far from these. Rod-shaped ZrN particles were observed near the surface (∼0.1 mm in depth) of alloys nitrided above 1673 K, and they were formed by the migration of grain boundaries sweeping up a high density of small precipitates in the grains.
At the nitrided layer front of alloys treated below 1623 K, a transition region occurred in which the hardness and the particle number density decreased gradually with depth. The formation of such a region is explained in terms of the low diffusivity of solute atoms. In this region a high density of the dislocations was also observed, which were induced to release volume expansion due to nitriding.
The nitriding kinetics obeyed a parabolic rate law in all cases. The layer thickness of alloys nitrided above 1673 K coincided with that predicted by Wagner’s theory, but below 1623 K the thickness with a transition region was larger than that predicted by the theory.View full abstractDownload PDF (1063K) -
Shotaro Morozumi, Tsuneo Odagi1981 Volume 45 Issue 10 Pages 1071-1077
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSStress-relieved and recrystallized specimens of Mo and TZM are tensile tested at strain rates of 4×10−5 to 4×10−1/s at room temperature with and without cathodic hydrogen charging prior to and/or during tensile testing. In the recrystallized specimens tested at the lowest strain rate, a little decrease in the lower yield strength and the ultimate tensile strength, and significant decrease in the reduction in area and the fracture stress are found by the charging during tensile testing. At strain rates up to 4×10−2/s, these properties are still affected by the charging, though they recover with increasing strain rate, and the effects of hydrogen charging disappear at the strain rate of 4×10−1/s. Microscopic observation shows that cleavage fracture has occurred in the recrystallized specimens tested with the charging during tensile testing, even though the specimens are fairly ductile. Little effect of cathodic charging on the tensile properties of the stress-relieved specimens is found. The effect of cathodic current density on the tensile properties is also investigated.View full abstractDownload PDF (809K) -
Hiroshi Takaku1981 Volume 45 Issue 10 Pages 1077-1086
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSurface-treatment effects on IGSCC susceptibility of sensitized 304 stainless steel in 561 K pure water were investigated concerning machining, grinding and shot peening. Main results obtained are as follows:
(1) In a subsurface layer severly worked by machining or grinding, residual tensile stress of 300–400 MPa and strain-induced martensite of 4–6% in the volume fraction were observed. The work hardening zone produced by these treatments was about 50 μm in thickness.
(2) Large compression of 500–750 MPa was retained after the shot peening in the subsurface. A large work-hardened zone 250∼350 μm thick and martensite of approximately 20% in the volume fraction were induced by this surface-treatment. In the case of high injection energy peened by 1.0 mm diameter shot, very large surface roughness of about 70 μm and microcracks were observed on the as-worked surface.
(3) The susceptibility of IGSCC of sensitized 304 stainless steel in 561 K pure water was increased by machining and grinding when tension above 300 MPa was produced on the worked surface.
(4) When the surface roughness was below about 20 μm and residual compression was above approximately 500 MPa, the shot peening treatment suppressed initiation of IGSCC in the SCC test up to the applied stress of 2.00 σy. However, even if residual compression was larger, occurrence of IGSCC was accelerated by the shot peening under the conditions of higher applied stress and more rough surface than the above values.View full abstractDownload PDF (1159K) -
Jun-ichi Masuda1981 Volume 45 Issue 10 Pages 1086-1093
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAcoustic emission during the yield process of a dispersion hardened alloy was estimated on the basis of dislocation movement through a random array of obstacles, using a computer.
The estimated acoustic emission event counts took a maximum at the yield point during the yield process. This result coincided with experimental results reported before. The yield stress was roughly a half of the stress which was calculated by Foreman and Makin, over the full range of the obstacle strength. With increasing obstacle strength, the estimated acoustic event count during the yield process increased, and then decreased.
The yield stress was proportional to the reciprocal of an average distance between the obstacles. The acoustic peak event count near the yield was proportional to the yield stress. This estimated result coincided with experimental results for dispersion hardened alloys reported before. When the obstacles with two differing strengths coexisted, the acoustic event count during the yield process took a naximum at a stress lower than the yield stress.
The acoustic event count, estimated in this study, was compared with the event count obtained by the experiment.View full abstractDownload PDF (650K) -
Tsugio Ogura, Akihiro Makino, Tsuyoshi Masumoto1981 Volume 45 Issue 10 Pages 1093-1101
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to examine usefulness of the grain boundary etching method (GEM) as a technique analyzing grain boundary impurity concentration, a saturated aqueous solution of picric acid containing a wetting agent was applied to 3.5%Ni-1.7%Cr-0.3%C steels doped with a small amount of P, S, Sb, Si or Sn.
Among all the samples examined, only one containing P suffered selective etching attack against grain boundaries. A promotive effect of C for the progress of etching was also confirmed. By applying both AES and GEM to the P-doped NiCr steel, it was found that the degree of etching attack against grain boundaries correlates well with the P concentration at grain boundaries. From these experimental evidences it was concluded that the selective etching attack of the present etching solution against grain boundaries in the NiCr steels is due to the existence of P at grain boundaries, and that GEM is useful as a technique analyzing grain boundary P concentration.
Application of the GEM using the same etchant was successfully made to a C-free NiCr steel which was hard to be broken intergranularly and was, therefore, impossible to be analyzed by AES. The heat of grain boundary segregation of P in the γ-range of the 0.3%C-NiCr steel and that of the C-free NiCr steel were obtained as 47 kJ/mol and 43 kJ/mol, respectively.View full abstractDownload PDF (973K) -
Setsuo Takaki, Yasutoshi Sujita, Youichi Tokunaga1981 Volume 45 Issue 10 Pages 1101-1106
Published: 1981
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe aging reactions in 18–20%Ni maraging steels containing Co, Mo and Ti have been investigated by means of calorimetric analysis and hardness measurement. With excess addition of Ti above about 1%, the formation of Mo rich zones, which is characteristic of Ti-free maraging steels, seems to be perfectly suppressed, and the precipitation of phases containing Ti is considered to occur.
In an Fe-18%Ni-10%Co-5%Mo-2.1%Ti alloy, for example, the specific heat versus temperature curve is characterized by the appearance of three evolution peaks at 470, 540 and 600°C, corresponding to the precipitation of a low temperature phase containing Ti, Ni3Ti(DO24) and Ni3Mo. On the isothermal aging at about 500°C, this alloy hardens by precipitation of the low temperature Ti-phase in the early stage and by precipitation of Ni3Mo in the later stage.View full abstractDownload PDF (513K)
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