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Volume 42, Issue 5
Displaying 1-17 of 17 articles from this issue
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Yoshio Hasegawa, Shinsaku Hanasaki, Masanori Yasutomi1978 Volume 42 Issue 5 Pages 441-447
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe cutting mechanisms of polycrystals of Al, Cu, Zn and Fe-3.5%Si are studied on the basis of those of single crystals of the same materials. For this purpose, the orthogonal cutting of Al-bicrystals (situated side by side in the cutting direction) were carried out and the effects of the grain boundary and the interaction of the adjacent grains on the cutting mechanism were investigated. The experimental results of polycrystals are compared with the results estimated from those of both single crystals and bicrystals.
The main results obtained are as follows:
(1) In cutting the bicrystals, the chip thickness changes drastically at the grain boundary. Then the chip is bent towards its thicker side. Consequently the chip thickness decreases gradually from the inside to the outside of the curvature.
(2) In cutting the bicrystals, the specific cutting resistance is obtained as the weighted average of each crystal with respect to its cutting width, but the side force (fs) varies from the weighted average.
(3) The interaction of the adjacent grains in a series position concerning the cutting direction has a greater influence than that in a parallel position on the cut surface.
(4) There is good agreement between the shear of polycrystals and the arithmetical mean value of the single crystals. The laryer the work-hardenability the smaller becomes the shear angle.
(5) The shear stress on the shear plane and the specific cutting resistance of polycrystals are larger than the arithmetical mean values of single crystals. Especially in Zn and Fe-3.5%Si, there are large differences between those values.View full abstractDownload PDF (669K) -
Hidenori Nagai1978 Volume 42 Issue 5 Pages 447-453
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn recent years non-magnetic steels with high strength and hardness are necessary for holders of electrical machinery and apparatuses, particularly pressing dies for making anisotropic ferrite magnets. Effects of cold-working and aging on the magnetic and mechanical properties of austenitic Fe-18W-12Cr-3Mo-XCo alloys (X: 25∼35 wt%) were studied.
The results obtained are as follows:
(1) In these alloys, the austenitic phase is stabilized as the Co content increased. Especially in Fe-18W-12Cr-3Mo-35Co alloy, the ferromagnetic phase is not observed after cold-working and aging.
(2) The micro-Vickers hardness of these alloys are changed remarkably with the non-magnetic precipitates, Fe7W6, Co7W6 and other compounds. The maximum hardness, after cold-working and aging, is around micro-Vickers 700.
(3) The Fe-18W-12Cr-3Mo-35Co alloy has the following mechanical properties; tensile strength 1030 MPa, 0.2% proof stress 427 MPa, reduction in area 20%, elongation 20%, micro-Vickers hardness 350, Young’s modulus 1.99×105 MPa. These values are superior to those of austenitic stainless steels in extensive use.View full abstractDownload PDF (573K) -
Tatsuhiko Ejima, Tsutomu Yamamura, Sei Takano, Tatsuya Honda1978 Volume 42 Issue 5 Pages 453-459
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDiffusion coefficients of Ir, Tl, Pb and Bi which belong to the sixth period were measured over the temperature range 1373 to 1573 K in liquid copper by means of the capillary reservoir method. The observed values were compared with the values calculated on the basis of a hard sphere model originally derived by Enskog.
The results obtained are summarized as follows:
(1) The diffusion coefficient of Ir in liquid copper is lower than the self-diffusion coefficient of solvent. The observed value agrees well with the one calculated taking into account the mass and the size effects on the basis of the hard sphere model.
(2) The diffusion coefficients and apparent activation energies for the diffusion of Tl, Pb, and Bi are considerably higher than those for the self-diffusion of liquid copper. This fact may be attributed to the presence of a diffusion mode with a long jump distance induced by the repulsive force between solute and solvent atoms.
(3) The apparent activation energies for the diffusion of solutes in liquid copper are higher than the observed ones. This fact indicates that the fluctuations not only in density but also in energy gives an important contribution to the diffusion in liquid metal.View full abstractDownload PDF (637K) -
Hironobu Nishikawa, Hiroshi Ebisu, Masayuki Yokoyama, Nobuo Mikuriya1978 Volume 42 Issue 5 Pages 459-463
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTwo sorts of etching solution revealing the etch pits at the sites of both aged and fresh dislocations on the (0001) surface of zinc crystals have been found. One of them (solution N-1) is composed of 80 cm3 of glacial acetic acid, 0.5 cm3 of 35∼37% hydrochloric acid, 0.5 cm3 of 60∼62% nitric acid, 0.5 cm3 of 47% hydrobromic acid and 1000 cm3 of deionized water, and produces the hexagonal pyramidal pits whose edges are parallel to the ⟨11\bar20⟩ directions. Another solution (solution N-2) is composed of 10 g of ammonium nitrate, 10 g of ammonium chloride and 1000 cm3 of 28% ammonia water, and produces the hexagonal pyramidal pits whose edges are parallel to the ⟨1\bar100⟩ directions. These solutions can develop the deep pits without roughening the observation surface. They are superior to the conventional etchants in etching the terminal points of dislocations on the (0001) surface. They are especially useful for the measurement of the densities and for the observation of the arrangements of the nonbasal dislocations in zinc crystals.View full abstractDownload PDF (1040K) -
Ryuichiro Oshima, Eizo Naya1978 Volume 42 Issue 5 Pages 463-469
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe β1 phase of Cu-Zn alloys containing α precipitates of 20∼40% in volume fraction exhibits a remarkable reversible shape memory effect (RSM) on cooling and heating between room temperature and −196°C after deforming at −196°C below the Ms temperature. The role of the α precipitates in the RSM was examined by optical and electron microscopy, electrical resistance measurements and tensile tests between room temperature and −196°C. On cooling a specimen of the (α+β1) phase to −196°C, the β1 crystals transform to the β1″ martensite. When small stress is applied to the specimen at −196°C, the β1″ martensite crystals are supposed to deform by the interchange of variants or the movement of planar defects such as stacking faults or twin faults, but the α crystals are deformed by dislocation motion. During the reverse martensite transformation on heating, it is thought that the interchange of martensite variants and/or the displacement of planar faults is completely reversed, and the normal shape memory effect appears. On the other hand, the dislocations formed in the α crystals at low temperatures remain and the internal strain energy is well conserved. The dislocation pile-ups against the boundary of neighboring β1 crystal were frequently observed in the α region. It is concluded that the stress concentration by these dislocation pile-ups induces particular variants of martensite in the β1 crystals at low temperatures, and these martensite crystals cause a spontaneous shape change of the material on cooling.View full abstractDownload PDF (1016K) -
Katsutoshi Ono, Toshio Fujimura, Joichiro Moriyama1978 Volume 42 Issue 5 Pages 469-474
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe limit on the use of CaF2 in galvanic cells for thermodynamic measurements under reducing conditions was studied by determining the a.c. conductivity from 880 to 1120 K with fluorine chemical potentials ranging from Co-CoF2 to Ca-CaF2 coexistence. The conductivity of CaF2 single crystal was determined by the a.c. bridge measurement-complex impedance plot combination method. Fluorine activities were established by using metal-metal fluoride electrodes.
The data showed that the conductivity values for the Mg-MgF2, Al-AlF3, Mn-MnF2 and Co-CoF2 electrodes were scattered more or less randomly and the conductivity values for the Ca-CaF2 electrode which is the stability limit of CaF2 were evidently higher than the values obtained for the other electrodes. It was suggested that the isothermal logσ vs logPF2 plot remains flat all the way down to the Mg-MgF2 electrode. This is indicative of an ionic conductivity which is independent of PF2, and the rise in conductivity for the Ca-CaF2 electrode would be due to partial electronic conduction.View full abstractDownload PDF (490K) -
Hakaru Masumoto, Kiyoshi Watanabe, Masao Mitera1978 Volume 42 Issue 5 Pages 474-479
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCrystal structures and magnetic properties of Mn-21.0∼35.0 at%Ga alloys have been investigated by means of X-ray diffraction, thermal expansion and magnetic measurements. It has been found that a metastable phase is revealed in the face-centered tetragonal DO22-type alloys in the composition range of 23.5∼31.2 at%Ga when reheated at 350∼450°C after water-quenching from the γ-Mn phase.
This metastable phase has lattice parameters a of 7.09∼7.18×10−10 m and axial ratios c⁄a of 1.816∼1.840. Both of the values increase wrth Ga concentration. These DO22-type alloys in the Mn-Ga system have coercive forces greater than 3.7×105 A/m and a magnetocrystalline anisotropy constant of about 1.4×106 J/m3.View full abstractDownload PDF (426K) -
Takeshi Kanomata, Takao Goto, Hideaki Ido1978 Volume 42 Issue 5 Pages 480-484
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMagnetic and crystallographic investigations of the compounds Fea−xMnxAs (3.0≥a≥1.90, a≥x≥0) are described. The homogeneity range with Cu2Sb-type structures in the system Fea−xMnxAs is situated between the composition a=2.0 and a=2.4. In the compounds Fea−xMnxAs with a>2.0 the excess metal atoms occupy interstitial sites in the site I layer perpendicular to the c axis. First-order ferri-→antiferromagnetic transitions with increasing temperature are found over a limited range of compositions in the system Fea−xMnxAs. The ferri-→antiferromagnetic transition temperatures Ts increase with increase in the composition a and x. On the contrary the spontaneous magnetizations and temperature coefficients of the magnetic flux density dB⁄dT at Ts decrease with increase in the composition a and x.View full abstractDownload PDF (398K) -
Osamu Michikami1978 Volume 42 Issue 5 Pages 484-491
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe solid solution of silver containing 0.27∼5.11 wt%Ga was internally oxidized at temperatures between 450 and 800°C in still air. The effects of oxidation temperature, oxidation time, solute content, depth and annealing temperature before oxidation on hardness were investigated.
(1) The internal oxidation velocity of silver alloys with less than 1.36 wt%Ga increased with decreasing Ga content and rising oxidation temperature. Hardness of the alloys internally oxidized at 500°C showed a maximum value and decreased with rising oxidation temperature above 600°C.
(2) Hardness of internally oxidized alloys was influenced by the annealing condition before oxidation. Hardness of the alloys internally oxidized after annealing at temperatures above 600°C was higher than that of the alloys internally oxidized after cold-working. Hardness of the alloys oxidized after annealing at 400°C showed a minimum value, and the alloys with more than 1.04 wt%Ga did not harden.
(3) The minimum hardness behavior of the alloys oxidized after annealing at about 400°C was attributed to the concentration of the solute atom in a thin layer of the surface.
(4) Hardness of the internal oxidation zone gradually decreased with increasing distance from the surface. The variation of the solute gallium in the oxidized zone was not observed. At the oxidation front, the hardness discretely decreased and was equal to that of the substrate annealed, and the Ga depleted zone was not observed.View full abstractDownload PDF (909K) -
Kazuhiro Yoshihara, Kazuyoshi Nii1978 Volume 42 Issue 5 Pages 492-498
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe surface self-diffusion coefficient of silver was measured by the grain boundary grooving method in atmospheres with various oxygen potentials. In an argon atmosphere with PO2=10−11 Pa, the surface self-diffusion coefficient can be expressed by the following equation:
Ds=0.249exp(−166 kJ/mol·RT)m2/s (973∼1073 K). This equation coincides well with Gjostein’s experimental formula for fcc metals.
As the oxygen potential increased from PO2=10−11 Pa, the surface self-diffusion coefficient decreased and became minimum at PO2=10−2 Pa. At PO2=10−2 Pa, the temperature dependence of the surface self-diffusion coefficient cannot be expressed by Arrhenius’ equation. As the oxygen potential further increased above PO2=10−2 Pa, the surface self-diffusion coefficient increased and the activation energy for the diffusion at PO2=105 Pa was smaller than that at PO2=10−11 Pa. The surface self-diffusion coefficient at PO2=105 Pa can be expressed by the following equation:
Ds=1.71×10−3exp(−106 kJ/mol·RT)m2/s (973∼1073 K).
The following model for the surface structure of silver at various oxygen potentials has been proposed. At PO2=10−11 Pa, oxygen ions are hardly adsorbed and the surface of silver remains clean. At PO2=10−2 Pa, oxygen ions are adsorbed locally, and neighboring silver atoms are ionized and stabilized. Then the number of sites, from which mobile adatoms that contribute to the diffusivity are produced decreases. Therefore, the surface self-diffusion coefficient decreases. At PO2=105 Pa, the adsorbed oxygen ions are arranged in order and a 2-dimensional ionic crystal is formed on the surface. Then the jumping distance becomes longer and the activation energy for the diffusion becomes smaller by an overlapping of long range Coulomb’s force. As a result, the surface self-diffusion coefficient increases.View full abstractDownload PDF (772K) -
Masanobu Ohmori, Keisoh Hashimoto1978 Volume 42 Issue 5 Pages 499-502
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA pure zinc with mean grain diameters ranging from 15 to 19 μm was tested in tension and torsion under pressures at various strain rates to examine the difference between the brittle-to-ductile transition pressures found in both deformations, respectively. The results obtained here are summarized as follows:
(1) The transition pressure of the fine grained zinc with a given grain size was always higher in tension than in torsion when deformed at a given strain rate as well as the transition pressure for the cast zinc.
(2) The brittle-to-ductile transition for the specimen with a grain diameter smaller than 15.7 μm was caused when the hydrostatic stress component in the specimen reached a certain value irrespective of the deformation mode. Beyond 15.7 μm in grain size, however, the hydrostatic stress component at the transition pressure was algebraically smaller in the tensile specimen than in the torsion one.
(3) In both tension and torsion, the transition pressure increased linearly with increasing logarithm of the strain rate encountered in the present experiment.View full abstractDownload PDF (319K) -
Kenji Morii, Mitsuo Mera, Yutaka Nakayama1978 Volume 42 Issue 5 Pages 502-508
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe contribution of shear bands to the orientational changes in (211)[\bar111] single crystals of 70/30 brass has been evaluated. The changes in orientation Δθ, and the shear strain Δγ and volume fraction VV of the shear bands during rolling of these single crystals have been measured as a function of rolling reduction. On the basis of the deformation models for the activation of shear bands, Δθ, Δγ, and θ the angle between shear bands and specimen surface have been calculated. It is concluded from the comparison between the experimental and calculated results that the formation of the {111}⟨211⟩ duplex orientations and the stabilization of them during rolling of the (211)[\bar111] single crystals could be attributed to the activation of shear bands. The analysis of the selected area diffraction patterns in electron microscopy and the results of the measurements of VV show that the development of the {011}⟨100⟩∼{011}⟨211⟩ orientation in the (211)[\bar111] single crystals rolled up to higher reductions results from the textures formed within the shear-band regions of which volume fraction has been increased with rolling reduction.View full abstractDownload PDF (825K) -
Hideo Ike, Hirobumi Okabe, Eiji Tsuji1978 Volume 42 Issue 5 Pages 509-517
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study has been made on the effects of low aluminum additions, 0.1 to 2.0%, on oxidation behavior of Fe-14Cr alloys in flowing 1 atm oxygen in the temperature range 900 to 1200°C. For all the alloys tested, no simple rate law is obeyed even at low temperatures where steady state processes are observed, indicating some complexity in scaling behavior. A minimum has been found to appear at 0.3%Al in the weight gain vs Al content relation after oxidation for 24 h. The oxidation resistance of 2.0%Al alloy, which shows good protection at and below 1000°C, decreases rapidly at higher temperatures mainly owing to well grown oxide warts or nodules, the nucleation of which takes place almost exclusively along the specimen edges. The extent to which both spalling and nodular growth of scales occur increases with increasing Al content in the range from 0.3 to 2.0%Al. A metallographic study, including SEM observation and EPMA examination, of the cross sections of oxidized specimens has revealed the formation of internal oxidation zones of α-Al2O3 particles for all but 2.0%Al alloy. The main types of scale structure are the (Fe, Cr)2O3 layer with an internal oxidation zone and the (Fe, Cr)2O3 layer with an inner layer of α-Al2O3, which are typically revealed in 0.3 and 2.0%Al alloys respectively. An intermediate scaling behavior between 0.3 and 2.0%Al alloys is observed in 0.8%Al alloy at and below 1100°C, i.e., the scale contains both of the typical layers, the ratio of areas between the two being roughly equal to unity. It has been deduced that the internal oxidation plays an important role in stabilizing the outer scale by acting as oxygen getters and at the same time giving sites for vacancy sink thereby avoiding void formation at the alloy/scale interface. The good oxidation resistance observed in 0.3%Al alloy is thus considered to be mainly due to the internal oxidation in the best form among the alloys tested.View full abstractDownload PDF (1287K) -
Mitsumasa Kishida, Kenzo Igaki1978 Volume 42 Issue 5 Pages 518-522
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFocussing and separation of complex ions of some transition metals in solutions of hydrochloric acid by column electrophoresis with silica gel powder as support medium have been studied under a gradient of temperatures, without a gradient of hydrochloric acid concentration.
Chloro-complex ions of some transition metals change sign of their charge from positive to negative with increasing temperature. The direction and velocity of the electromigrating complex ions of Co(II), Cu(II), and Fe(III) can be controlled by changing temperature. The zone of metal complex ions is focussed under temperature gradient at the position where the temperature causes the mean charge of the complex ions to become zero.View full abstractDownload PDF (399K) -
Toshio Shimoo, Hiroshi Kimura1978 Volume 42 Issue 5 Pages 523-526
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe state of carbon dissolved in molten binary CaO-Al2O3 slag has been studied. The sample of this slag was melted in a graphite crucible with or without carbon saturated iron, and the amount of CO evolved was measured by means of the thermo-balance. Then, the amounts of carbon dissolved in slag and aluminium transferred from slag to metal were determined by chemical analysis, and the amount of CO was calculated on the basis of stoichiometry. From a comparison between the measured and calculated amounts of CO evolution, it is supposed that carbon dissolved in slag as C2− is given by the following reaction; 2C+O2−=C2−+CO(g).View full abstractDownload PDF (278K) -
Yoshiro Kayahara, Katsutoshi Ono, Toshio Oishi, Joichiro Moriyama1978 Volume 42 Issue 5 Pages 527-533
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe phase relationship in the liquid Cu-O system was determined by modifying the sampling method and oxygen analysis. The miscibility gap was seemed to disappear at higher temperature than 1620 K. Using the following cells, the emf’s of the cells were measured in the oxygen composition range from 0.8 to 11.5% and the temperature range from 1430 to 1600 K.
(1) Pt/Ni, NiO/ZrO2(+CaO)/Cu-O liq. alloy/LaCrO3, Pt
(2) Pt/Ni, NiO/ZrO2(+CaO)/Cu-O Liq. alloy, Cu2O(s)/LaCrO3, Pt
(3) Pt/Ni, NiO/ZrO2(+CaO)/Cu-O liq. alloy, Cu-O liq. oxide/LaCrO3, Pt
(4) Pt/Ni, NiO/ZrO2(+CaO)/Cu-O liq. oxide/LaCrO3, Pt.
\ oindentThe samples were taken at 1593 K and analysed for oxygen. The activity curves of oxygen and copper were drawn at 1573 K, and the standard free energies of formation of the solid and liquid Cu2O were determined from 1370 to 1600 K. The partial molal entropy of oxygen in the liquid Cu-O system showed its minimum at the Cu2O composition.
The oxygen potential-temperature-composition diagram for the Cu-O system were determined from the results of this study.View full abstractDownload PDF (582K) -
Nobutaka Narita, Akitoshi Hatano, Jin-ichi Takamura, Motoki Yoshida, H ...1978 Volume 42 Issue 5 Pages 533-541
Published: 1978
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSStacking fault energy γSF of fcc metals can be evaluated by knowing the twinning stress τT. In pure nickel, however, deformation twinning does not occur even at 4.2 K because of its high γSF. For this reason, measurements of τT for nickel-based alloys being subject to deformation twinning have been made, in order to evaluate the value of γSF for pure nickel by using an extrapolation method. Ni-Ge(1∼9 at%) alloy crystals oriented near ⟨111⟩ were chosen for this purpose and deformed in tension at 4.2 K. The main results are summarized as follows:
(1) Twinning takes place before the onset of necking in alloys containing Ge 5 at% or more, and the twinning stresses are reduced as the Ge content increases. (2) The values of γSF determined from the twinning stresses τT for Ni-5, 7 and 9 at%Ge alloys are 109, 90 and 76 mJ/m2, respectively. (3) The value of γSF extrapolated to pure nickel through the values of Ni-Ge alloys by using Gallagher’s expression is found to be γNi=149±3 mJ/m2. (4) The internal stress acting on the twinning dislocations, which arises from a dislocation pile-up in our model previously proposed, is not large but only about 1.3 times of the applied stress, so that the value of γSF can be evaluated with little effect of the number of piled-up dislocations, in marked contrast to the method of determining γSF from the cross-slip condition. (5) A very simplified formula for evaluating γSF from τT has been derived with a good approximation as γSF=ξ(R)τTbs, where ξ(R) is a parameter depending only on the specimen orientation, being nearly equal to 2 for the specimens oriented near ⟨211⟩, and bs is the Burgers vector of a Shockley partial dislocation.View full abstractDownload PDF (877K)
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