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Volume 57, Issue 4
Displaying 1-18 of 18 articles from this issue
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Hirofumi Wada, Masayuki Shiga1993 Volume 57 Issue 4 Pages 363-367
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMechanically ground YFe2 was studied by means of X-ray diffraction and the Mössbauer effect. It is shown that YFe2 decomposes into bcc Fe and amorphous Y-Fe by mechanical grinding. Mössbauer spectra of mechanically ground YFe2 can be analyzed by the superposition of three kinds of spectra: a sextet of bcc Fe, two sextets of mother YFe2 and a doublet of amorphous Y-Fe. Grinding period dependence of the fraction of Fe atoms in each state is determined. After 72 h milling, 50 and 40% of Fe atoms are incorpolated into the amorphous phase and bcc Fe, respectively. Assuming that Y is not solved in bcc Fe, the mean concentration of the amorphous phase is estimated to be Y0.45Fe0.55, being nearly independent of the grinding period up to 72 h. Magnetization of mechanically ground YFe2 is also studied. It is shown that the grinding period dependence of magnetization is well explained by the results of Mössbauer analyses.View full abstractDownload PDF (326K) -
Yakichirou Kawamo, Jirou Harase1993 Volume 57 Issue 4 Pages 368-376
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFe-3%Si containing AlN, which was cold-rolled with 84.7% reduction and primarily recrystallized, was heated with the heating rate of 15°C/h in the 85%H2-N2 (condition A) or in the 5%H2-N2 atmosphere (condition B) up to a temperature of 1200°C and extracted from 925°C at intervals of 50°C. The secondarily recrystallized grains were observed at 975°C in condition A, while no secondarily recrystallized grains were found in condition B at this temperature. The secondary recrystallization was completed at 1025°C in both conditions. No (101)[010] oriented secondary grains were observed in specimen A extracted at 975°C. However, the main secondarily recrystallized texture at 1025°C was (101)[010] in both conditions. The scatter from the ideal (101)[010] orientation was smaller and the grain size was larger in B condition compared with condition A at this stage. However, the scatter in condition B was larger compared with the one processed from the primarily recrystallized specimen containing both AlN and MnS as inhibitors.
These results are discussed from the viewpoint of grain boundary migration characteristics of coincidence boundaries and the following conclusion were derived.
(1) In the weaker inhibitor condition, selective migration of other than Σ9 type boundaries occurs in the lower temperature range and selective migration of Σ9 type boundaries mainly occurs over a higher temperature range.
(2) In the stronger inhibitor condition, selective migration of grain boundaries initiates over the higher temperature range and they are mainly Σ9 type boundaries.View full abstractDownload PDF (1868K) -
Setsuo Aso, Michihiro Tagami, Shoji Goto1993 Volume 57 Issue 4 Pages 377-383
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFive kinds of phases were detected in the liquidus phase diagram of the Fe-15%Cr-C-B alloy system. Two types of peritectic reactions {L+M2B→M3(C, B) and L+M7(C, B)3→M3(C, B)} and four types of eutectic reactions {L→γ+M2B, L→γ+M3(C, B), L→γ+M23(C, B)6, L→γ+M7(C, B)3} were also detected on each liquidus phase boundary. The sum of carbon and boron concentrations in each boro-carbide was almost constant; that is, the sum was about 5.5% in M3(C, B), about 4.7% in M23(C, B)6 and about 7.5% in M7(C, B)3; however, the carbon and boron concentrations in each boro-carbide changed compensatory in these constant concentrations. In the M2B liquidus phase region, two types of boride were detected: one was a columnar boride with high boron content, which was identified as a M2B type boride, the other was a plate-like boride with low boron content, which was still unknown in this investigation. The conjugate relations of γ phase and the compound phase were in good agreement with the solidification structures.View full abstractDownload PDF (1306K) -
Tomohiro Aikawa, Yoichi Nishino, Shigeru Asano1993 Volume 57 Issue 4 Pages 384-388
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn X-ray diffraction study was performed on Fe-Mn (16 to 41%Mn) alloys charged cathodically with hydrogen. In the alloys with the γ-single phase, a hydrogen-induced transformation to an hcp εH phase is found after hydrogen charging. On the other hand, in the alloys with the γ and ε phases, there is little change in the γ phase, but a considerable lattice expansion is observed for the ε phase. This means that the ε phase preferentially absorbs hydrogen. Especially in the Fe-27%Mn alloy, the ε phase gradually expands with increasing charging time, and finally the εH phase is separated from the ε phase. Therefore, the formation of the εH phase should be regarded as a phase separation in the hcp matrix ε enriched with hydrogen, although it apparently seems to be a martensitic transformation.View full abstractDownload PDF (442K) -
Hiroyuki Ogawa, Yoichi Nishino, Shigeru Asano1993 Volume 57 Issue 4 Pages 389-393
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMechanical hysteresis in alumina with microcracks has been investigated by a loading-unloading test in the microstrain range around 10−4 and examined in comparison with the strain amplitude dependence of internal friction. While there remains a permanent strain after the initial loading, successive cyclic loading stabilizes the mechanical response, resulting in a single closed hysteresis loop with a symmetrical shape. Such a stabilized hysteresis loop is responsible for the internal friction based on the friction mechanism and can be attributed to the microplasticity in the forerunning process of fracture. With increasing strain amplitude, the area enclosed by the stabilized hysteresis loops increases remarkably. Since the loop area determines the energy loss per cycle, its strain amplitude dependence is considered to arise from the same origin as that of internal friction. The internal friction data have also been analyzed on the basis of the theory of microplasticity. The stress-strain responses thus obtained show that the microplastic strain of the order of 10−9 increases nonlinearly with increasing effective stress. The variation in the microplastic flow stress corresponds well to the decrease in the macroscopic fracture strength resulting from the formation of microcracks and crack propagation.View full abstractDownload PDF (479K) -
Yoshihiro Nakayama, Tetsuya Takaai1993 Volume 57 Issue 4 Pages 394-401
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe X-ray elastic constants of the cold-rolled 5083 aluminum alloy were measured for the crystal planes (311) and (222) by using CrKα characteristic X-rays. The diffracting plane dependence of X-ray elastic constants as well as the variations of X-ray elastic constants due to the cold rolling, were studied experimentally. The following conclusions were obtained: (1) Reasonable measurement of X-ray elastic constant was closely related to the variations of integrated intensity which was affected by the formation of rolling textures. (2) Certain inconsistency was observed between the elastic constants values measured by mechanical procedures and those measured applying X-ray diffraction method. (3) The diffracting plane dependence of X-ray elastic constants was observed for the (311) and (222) planes. X-ray elastic constants of the (311) plane decreased with increasing reduction in area by cold rolling.View full abstractDownload PDF (899K) -
Satoru Yamamoto, Masataka Mizuno, Hisayoshi Kobayashi1993 Volume 57 Issue 4 Pages 402-409
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn the present work, the shape, orientation relationship and composition of G.P. zone in Al-Cu, Al-Zn and Al-Ag alloys and further the influences of additional elements on the formation of G.P. zone in Al-Cu alloy has been estimated by the calculation of energy and energy fluctuation of cluster-models by the Extended Hückel Method.
The results of calculations are as follows: The {100} plate-like G.P. zone of 100%Cu in Al-Cu alloy, spherical G.P. zone of 30.23%Zn(Ag) in Al-Zn(Ag) alloy has the lowest energy among the models used in this work. These results are consistent with the esperimental results except the chemical composition of G.P. zone. As for the influences of additional elements on the stability of G.P. zone, the additional elements which retard the rate of aging lower the energy of G.P. zone clusters and decrease its energy fluctuation, stabilizing G.P. zone. On the contrary, the additional elements which suppress the formation of G.P. zone increase the energy and energy fluctuation of G.P. zone cluster and therefore unstabilize G.P. zone. Based upon these results, it can be said that the Extended Hückel method is effective for the estimation of the shape, orientation relationship of G.P. zone and the influences of the additional elements on the formation of G.P. zone but its application to the estimation of chemical compositions of G.P. zone is difficult. Calculation by the Extended Hückel method may provide a new point of view to understand precipitation phenomena comprehensively.View full abstractDownload PDF (942K) -
Masatoshi Kato, Takashi Sakaki1993 Volume 57 Issue 4 Pages 410-416
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCr exhibited much better corrosion resistance to H2SO4 and HCl than those of Fe-Cr alloys and Ti at low temperature and low concentration. Because a wide passive potential range with a low passive current was observed for Cr in H2SO4 and HCl solutions. However Cr was severely corroded in high temperature or concentrated conditions. The corrosion resistance of Cr was improved by adding noble metals such as Pd and Ru.
The corrosion behavior of Cr-Pd and Cr-Ru alloys in H2SO4 solutions was investigated by measurement of the polarization curves, the change in corrosion potential with time and the average corrosion rate. And then, surface filmes of Cr-based alloys immersed in H2SO4 have been studied by means of AES and ESCA.
The corrosion resistance of Cr-based alloys in H2SO4 was improved by adding noble metals such as Pd and Ru. The addition of Pd and Ru to Cr increased the cathodic current, and decreased the anodic dissolution current in the active state. Accordingly the corrosion potential of the alloys shifted to the noble direction and the alloys were easily passivated. And the addition of Ru is more effective than that of Pd at a high temperature up to 400 K.
The composition of the surface films formed on Cr-Ru and Cr-Pd immersed in H2SO4 were Cr oxide such as Cr2O3. Ru and Pd were concentrated in these films. SO2−4 existed in the surface oxide films. Pd in the surface oxide films exist in the form of Pd0, and Ru in the form of Ru2+. The effect of the Pd addition on the corrosion behaviour of Cr is caused mainly by cathodic depolarization, while the effect of the Ru addition is caused by cathodic depolarization and improvement of the passive films on Cr.View full abstractDownload PDF (631K) -
Eiji Takasaka, Nobuya Iwamoto1993 Volume 57 Issue 4 Pages 417-420
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPreferred orientation behavior of Cr-N film prepared by the IBED (Ion Beam Enhanced Deposition) method was studied. When arrival ratio R(Cr/N) was low (R=4.3, 8.6), chromium nitride films preferentially occupied a plane with low Miller indices such as (100) groups. On the other hand, chromium nitride did not take preferred orientation, when the arrival ratio was high (R=35.3, 70.6).
The authors suggested a new model of the film formation to explain the preferred orientation in this study. In this model based on the concept of anisotropy of irradiation, it is defined that the selection and conservation of a crystal plane and a crystal system should occur to minimize the energy loss of irradiated ions.View full abstractDownload PDF (301K) -
Yuichi Sato, Toshio Yamada, Takashi Sato1993 Volume 57 Issue 4 Pages 421-426
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCasting examinations by using a multi-orifice nozzle were carried out to establish a casting process for ultra-wide ribbon in the single roller process. Orifices of every nozzle used were rectangular and a longitudinal side of the rectangular orifices was arranged along the casting direction. It was found that it was possible to coalesce each melt paddle formed between each orifice and the wheel surface across the width of the ribbon by optimizing the dimensions and interval of orifices of the nozzle. However, the free surface of the ribbon obtained undulated regularly across the width. This regular undulation on the free surface of the ribbon seemed to result from the regular difference of the length of the melt puddle in the casting direction across the width of the ribbon. From the results of the present examination, it is considered that the ribbon with a flat surfaces can be obtained, if it is realized to make the length of the melt puddle in the casting direction uniform across the width of the ribbon by using the multi-orifice nozzle.View full abstractDownload PDF (670K) -
Yuichi Sato, Toshio Yamada, Takashi Sato1993 Volume 57 Issue 4 Pages 427-431
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCasting examinations by using a multi-orifice nozzle were carried out to establish a casting process for ultra-wide ribbon in the single roller process. Orifices of every nozzle used were parallelogram. The dimensions of the orifices of the nozzle were varied to examine the influence of design of the orifice of the nozzle on the uniformity in the thickness of ribbon obtained. It was found that the design of the orifices of the nozzle affected the uniformity in the ribbon thickness. The ribbon with uniform thickness was obtained by using of a nozzle consisting of orifices whose total length along the casting direction was constant across the width of the ribbon obtained. This seems to mean that a nozzle with design optimized in the present work makes the length of the melt puddle in the casting direction uniform across the width of the ribbon, which results in the ribbon with uniform thickness.View full abstractDownload PDF (1146K) -
Yukinori Ono, Tsutomu Takechi, Keisaku Ogi1993 Volume 57 Issue 4 Pages 432-439
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe redistribution of chromium and carbon during solidification of primary austenite was evaluated for Fe-Cr-C alloys by a finite difference method. In the calculation, the diffusion of chromium and carbon were estimated in both solid and liquid phases. The equilibrium partition was assumed at the interface between solid and liquid, though the partition coefficients of chromium and carbon varied depending on the alloy contents of liquid phase.
EPMA analysis was also made on Fe-10.84%Cr-0.95%C and Fe-5.34%Cr-0.92%C alloy specimens solidified at a cooling rate of 0.167 K/s to reveal the chromium and carbon distribution in primary austenite. The comparison of experimental values with the calculated ones revealed the diffusion of chromium in austenite was very slow and resulted in the microsegregation, while carbon diffused completely and exhibited uniform distribution in austenite. The partition coefficient of chromium decreased gradually with the increase in the fraction of solid, fS, and that of carbon changed little until fS=0.7 and then gradually decreased. These changes in partition coefficients remarkably influenced the redistribution of elements.View full abstractDownload PDF (795K) -
Hisaoki Sasano, Hitoshi Arai, Toshiyuki Suzuki1993 Volume 57 Issue 4 Pages 440-444
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWe attempted to precisely control the zinc concentration in copper alloys by regulating the heating temperatures of pure copper and the molten zinc source placed in a closed vessel independently.
In this experiment, the diffusion phenomena in a solid copper-zinc vapor diffusion couple were investigated. The results obtained are as follows: (1) The smaller was the difference in heating temperature between copper plates and molten zinc more zinc diffused into the copper plate. (2) The zinc concentration on the surface of the copper plates laid only in the single alpha, beta and gamma phase regions in the copper-zinc binary phase diagram and kept constant values even when the heating time changed. (3) It was found that the activity of zinc in copper depended on the temperature. (4) The interdiffusion coefficient in the beta phase was about 500 times larger than that in the alpha phase, and the growth rate of the beta phase layer formed on the surface was mainly controlled by the diffusion rate of zinc in the beta phase.View full abstractDownload PDF (646K) -
Hisaoki Sasano, Hitoshi Arai, Toshiyuki Suzuki1993 Volume 57 Issue 4 Pages 445-448
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe method to produce a Cu-Zn-Al shape memory alloy by heating Cu-Al alpha solid solution alloy in zinc vapor is proposed. It was found that the alloys with any concentration of zinc in the β phase region could be prepared by proper choice of the heating condition, and that it was possible to control the shape recovery temperature with an accuracy of 1 K when the heating temperature is controlled with an accuracy of 0.1 K. The shape recovery strain and the fracture elongation of the alloy prepared by this method were slightly smaller than those of the alloy prepared by the conventional process. This method makes it possible to produce the concentration-gradient alloy and to readjust the concentration of zinc in the finished parts.View full abstractDownload PDF (423K) -
Masahiro Okumiya, Yoshiki Tsunekawa, Itaru Niimi, Kazumi Kurata, Akira ...1993 Volume 57 Issue 4 Pages 449-454
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn conventional gascarbonitriding, voids appeared in a surface layer right after the nitrogen content reached about 0.4 mass%, and then the nitrogen content decreases rapidly. The authors have established the novel method named a retained ammonia rising method that gives higher nitrogen contents without void formation. The influence of retained ammonia rising rate in the new gascarbonitriding process on the void formation and nitrogen content was studied using pure iron and low carbon steel foil with a thickness of 0.25 mm. Wear-resistance and fatigue limits for bulk specimens that were treated by the retained ammonia rising method were studied using medium carbon steel.
The critical nitrogen contents for void formation in pure iron [CNp] and in low carbon steel [CNl] were described by the logarithm equations with the variable treating times [t], respectively.
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The rising rate of retained ammonia for void formation [R] was also described by the exponential equations with the variable CNp or CNl.
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For example, at the treating time of 1.8 ks, by the ammonia rising method, the critical nitrogen content of pure iron foil for void formation was 0.78 mass%, that was about 1.5 times that in conventional gascarbonitriding. The critical nitrogen content of low carbon steel foil for void formation was 0.81 mass%, that was about three times that in conventional gascarbonitriding.
The wear resistance of medium carbon steel treated by the ammonia rising methed was about twice that in conventional gascarbonitriding. This is due to the improvement in resistance to temper softening and also to the increase in surface hardness through martensite transformation of the retained austenite during the wear test.
Fatigue limits of medium carbon steel treated by the ammonia rising method did not differ from those in conventional gascarbonitriding. The retained austenite which prevented cracks from initiation and propagation was transformed into martensite during the fatigue test.View full abstractDownload PDF (499K) -
Takashi Yebisuya, Takashi Kawakubo1993 Volume 57 Issue 4 Pages 455-462
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBismuth-tin-lead alloys have great potentialities for use as a low-temperature solder for microelectronics applications. The high-temperature mechanical properties of these alloys have not been examined, in spite of their importance to mechanical and thermal reliability. A series of tensile and creep tests was performed on 58%Bi-Sn, 55.5%Bi-Pb, 52.5%Bi-15.5%Sn-Pb, 21%Bi-37%Sn-Pb, and 14%Bi-43%Sn-Pb cast alloys (in mass%), and the results were compared with those for Sn-Pb eutectic solder.
The minimum creep rate was well expressed by the power creep law, \dotε=Aσn. For Bi-Sn, Bi-Pn and Bi-Sn-Pb eutectic alloys, the stress exponent, n, was almost constant between 3 and 5, corresponding to the value for pure alloys, and the apparent activation energy was 125 kJ/mol, 139 kJ/mol, and 97 kJ/mol, respectively. Comparing tensile properties with the creep behavior, the effects of temperature were similar in both cases, although the dependence of strain (or creep) rate on tensile (or creep) strength was not coincident.View full abstractDownload PDF (1378K) -
Hirohiko Ohmura, Kouji Kawashiri, Tohru Yoshida1993 Volume 57 Issue 4 Pages 463-469
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of the Fe foil insert on the Charpy U-notch impact value for stainless steel (JIS SUS304)/high-carbon steel (1.04%C) joint brazed with Cu filler metal(JIS BCu-1) was investigated in a temperature range from 193 to 973 K. Furthermore, the SUS304/high-carbon steel joint with the Fe foil insert was compared to the other joints brazed with Au filler metal (BAu-2), Ni filler metal (BNi-2) and Ag filler metal (BAg-8).
When inserting the 0.3 mm thick Fe foil between the base metals prior to the Cu brazing in order to prevent the formation of Cr23C6 and Cr7C3 carbides at the high-carbon steel braze interface due to the dissoluion of SUS304, the dissolution and deposit of base metal takes place on either side of the foil: On the high-carbon steel side, the high-carbon steel and the Fe foil are united with the columnar Fe-9∼7%Cu-0.8%C alloy which comes from the high-carbon steel, and on the SUS304 side, the SUS304 and the Fe foil are also united with the columnar Fe-13∼12%Cr-9∼6%Cu-5∼4%Ni-0.2%C alloy coming from the Fe foil. As a result, both SUS304 and high-carbon steel base metals are united with each columnar phase through the foil, so that the impact value of the joints increased markedly from 1.3 to 11.2 J/cm2 at room temperature.
Moreover, this uniting with each columnar phase exhibited a remarkable effect on the impact value of the joint in the range between room temperature and 973 K compared to the other joints brazed with BAu-2, BNi-2 and BAg-8. Also, it was possible to braze the SUS304 to the graphite, instead of high-carbon steel, with BCu-1 by inserting the Fe foil.View full abstractDownload PDF (1086K) -
Yuji Kaneko, Kazuhiko Majima, Shigeru Kastuyama, Hiroshi Nagai1993 Volume 57 Issue 4 Pages 470-477
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of B content on the sintering behavior of Nd15Fe85−xBx (x=4∼10 at%) alloy powders were investigated through microstructural observations, and measurements of DTA, linear shrinkage and magnetic properties. In the case of x≥6 at%, a liquid phase forms from ternary eutectic reaction of Nd-rich, Nd2Fe14B and Nd1.1Fe4B4 phases at 938 K. While the shrinkage below 1300 K is very small because of a lack in the amount of the liquid phase, remarkable shrinking occurs when the sintering temperature is raised above 1300 K. On the other hand, in the case of x<6 at%, a liquid phase forms from a reaction betweem Nd-rich and Nd2Fe17 phases at 963 K. In this case, shrinkage starts rapidly corresponding to the appearance of the liquid phase and continues at a constant rate to higher temperatures. This is probably due to the increase of the amount of the liquid phase and the reaction between Nd2Fe17 and Nd2Fe14B phases, causing the liquid flow and solution-precipitation.View full abstractDownload PDF (1367K)
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