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Volume 54, Issue 11
Displaying 1-21 of 21 articles from this issue
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Hiromi Miura, Xuejun Tong, Masaharu Kato, Tsutomu Mori1990 Volume 54 Issue 11 Pages 1165-1170
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBy internally oxidizing Cu-0.06 mass%Si bicrystals with various symmetric [011] tilt boundaries, SiO2 particles were introduced in the Cu matrix and on the grain boundaries. Transmission electron microscopy revealed that while the SiO2 particles in the Cu matrix were spherical, the boundary SiO2 particles had lenticular shapes. The boundary energies of Cu (γB) were determined with reference to the isotropic Cu-SiO2 interfacial energy (γI) by measuring the shape of the boundary SiO2 particles. When γB⁄γI was plotted against misorientation (θ), energy cusps were observed at θ=39° (Σ9), 70.5° (Σ3) and 130° (Σ11) with the deepest cusp at θ=70.5°. The effect of oxygen segregation on boundary energy was examined by applying internal oxidation and degassing treatments to the bicrystals. It was found that the boundary energy became larger as the amount of oxygen at the boundaries increased. After a short internal oxidation or degassing treatment, the γB⁄γI values were measured as a function of the depth from the surface for the bicrystals with θ=39° and 130° boundaries. γB⁄γI was found to be constant, independent of the depth from the surface, for the θ=39° boundary while it was dependent on the depth for the θ=130° boundary. Since the θ=39° boundary has a larger energy than the θ=130° boundary, it is concluded that the boundary oxygen diffusivity is larger in a higher energy boundary.View full abstractDownload PDF (1434K) -
Hideyuki Ikeda, Hidehiko Matsuda1990 Volume 54 Issue 11 Pages 1171-1176
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWe have simulated the cluster formation processes in a substitutional bcc binary alloy with an anisotropic elastic interaction by using a Monte Carlo method combined with the static variational method. The Johnson-type potentials were used for the potentials between the constituents.
As a result, we observed a rearrangement of clusters and anisotropic precipitation in the alloy and that the total interatomic energy decreased non-linearly by the displacement of each atom with time evolution.View full abstractDownload PDF (1040K) -
Akira Takeuchi, Toshiyuki Koyama, Takao Kozakai, Toru Miyazaki1990 Volume 54 Issue 11 Pages 1177-1182
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA new Fourier expression of the Cahn-Hilliard’s flux equation is proposed, where the regular solution approximation is adopted as the chemical free energy of solid solution and the mobility is defined as a function of solute composition. The results of the computer simulation of phase decomposition, derived on the basis of the new method, are in accord with the prediction from the phase diagram which is theoretically given by the free energy of the regular solution approximation. This calculation method is applicable to the actual alloy systems, because the phase diagrams have usually been evaluated, based on the regular solution or the modified regular solution model.View full abstractDownload PDF (748K) -
Yukio Inokuti, Mitsuru Yanagisawa, Chizuko Gotoh1990 Volume 54 Issue 11 Pages 1183-1190
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn an attempt to clarify the structure of the ⟨110⟩ fiber texture in the central area of hot rolled silicon steel sheet, computer color mapping was performed with image analyser using the orientation and strain data measured in advance in a Kossel examination. The results are summarized as follows: (1) The central area of the hot rolled silicon steel sheet is composed of grains elongated in the rolling direction, and it shows ⟨110⟩ fiber textures with {100}⟨011⟩, {100}⟨001⟩, near {113}⟨110⟩, and near {223}⟨142⟩. In this area, no {110}⟨001⟩ grain is formed. (2) In all the elongated grains, strain exists inside the grains themselves. Among them, the elongated grains of {100}⟨011⟩ and {100}⟨001⟩ have a small amount of strain and low lattice curvature (within 10°), whereas those of near {113}⟨110⟩ and near {223}⟨142⟩ have a large amount of strain and high lattice curvature (max. 30°). (3) The result of (2) is consistent with many previous experimental results of cold rolling and recrystallization using single crystals of silicon steel. (4) Most of the mutual elongated grains have high angle grain boundaries with a boundary width of 3 pixels. (5) The alternate formation of {100}⟨011⟩ or {100}⟨001⟩ and near {112}∼{111}⟨110⟩ elongated grains occurs during the processes from slab heating to hot rolling. Thus, the energy decrease due to the alternate formation of these orientations in the elongated grains plays a more important role rather than the energy increase due to the formation of the high angle grain boundary, and its alternate formation is indispensable for developing highly oriented (110)[001] secondary grains in the processes up to the secondary recrystallization after hot rolling.View full abstractDownload PDF (1373K) -
Yoshio Nakamura, Jirou Harase, Yasuo Okazaki, Nobuyuki Takahashi1990 Volume 54 Issue 11 Pages 1191-1198
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn attempt to clarify the mechanism of secondary recrystallization in aluminum killed steel, the orientation relationship between the secondary Goss grains and primary recrystallization texture was investigated by analysis of X-ray pole figure measurement. The main results obtained are as follows.
(1) In 70% cold rolling reduction, the intensity of the Goss orientation is high in the primary recrystallization stage and the evolution of Goss texture is considered to be originated in the higher PCNΣ9 value, a product of the intensity of Goss orientation and the intensity of Σ9 orientation in relation to the Goss orientation (ICΣ9 value) in the primary matrix.
(2) In 85% cold rolling reduction, the intensity of the Goss orientation in the primary matrix is lower, but the Goss orientation has a higher intensity of Σ9 orientations than any other orientations in the primary matrix. Therefore, the occurrence of the Goss secondary grains in this case is considered to be due to the higher ICΣ9 value.View full abstractDownload PDF (2130K) -
Tomoyasu Aihara, Kiyoshi Aoki, Tsuyoshi Masumoto1990 Volume 54 Issue 11 Pages 1199-1204
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe formation process of a hydrogen-induced amorphous phase in the C15 Laves phases, RNi2Hx (R=Sm, Gd, Dy, Er) has been examined by X-ray diffraction and differential scanning calorimetry as a function of hydrogenation time. It has been demonstrated that there are two kinds of amorphization processes. That is, the amorphization in SmNi2 and DyNi2 compounds progresses by the nucleation and growth of a hydrogen absorbed amorphous phase. On the contrary, in GdNi2 and ErNi2 a hydrogen absorbed compound transforms polymorphously to the amorphous ones with increasing time. The JMA plot for the process of amorphization gives the numerical exponent n=3.9 for DyNi2 and n=0.5 for GdNi2, respectively. The difference in the process of hydrogen-induced amorphization in these alloys is discussed.View full abstractDownload PDF (776K) -
Yutaka Hiraoka, B. C. Edwards, B. L. Eyre1990 Volume 54 Issue 11 Pages 1205-1213
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis paper reports the results of a study of the effects of nitrogen on the intergranular segregation and fracture behaviour of molybdenum. Samples exhibiting a ‘bamboo-type’ grain structure were nitrogen doped to various levels. Most of the grain boundary orientation deviated by an angle Δθ (1-10°) from the precise coincident site lattice orientation.
The driving force for oxygen segregation was greater than that for nitrogen segregation at the temperatures 1873-2233 K. Increasing the bulk concentration of nitrogen enhanced the oxygen segregation, whilst having a less significant effect on the nitrogen segregation.
The fracture energy decreased with increasing segregation levels of oxygen and nitrogen. However, it was suggested that the fracture energy was not solely a function of the grain boundary segregation but also depended on the geometrical nature of the grain boundary.View full abstractDownload PDF (1478K) -
Toshiro Kobayashi, Hiroyuki Asai, Shinji Yamauchi, Masaya Miyake1990 Volume 54 Issue 11 Pages 1214-1221
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA precise fracture toughness testing method in ceramics is required to be established. In the present study, requirements to obtain the valid fracture toughness values of sintered silicon nitride ceramic was examined in the static three-point bending test and instrumented impact test. Moreover, it is generally considered that the toughness of ceramics is influenced by microcracking or phase transformation at the crack tip process zone. It is important, therefore, to understand and clarify the properties of the process zone. Measurement of residual stress by the X-ray method and transmission electron microscope (TEM) observation were carried out for this purpose.
It was shown that fracture toughness was not affected by crack length (a) to specimen width (W) ratio a⁄W and span length (S) to specimen width ratio S⁄W. However, the fracture toughness was affected by specimen thickness (B) and notch root radius (ρ). Static and dynamic fracture toughnesses increased with increasing process zone size.
The valid fracture toughness value was obtained by precracked type specimen thicker than 4 mm. This condition was represented by B≥70(KIC⁄σmc)2, where σmc shows a local critical fracture stress at the process zone.View full abstractDownload PDF (1474K) -
Kazuo Kameda, Katsunori Yamaguchi1990 Volume 54 Issue 11 Pages 1222-1227
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe activity of the liquid Te-In system has been determined by the emf measurement of the following galvanic cell:
(This article is not displayable. Please see full text pdf.)
The activity of indium in liquid Te-In allays at 1000 K and 1050 K shows large negative deviations from Raoult’s law in the tellurium-rich region and remarkable negative to positive deviations from ideality in the indium-rich region. The activity of tellurium at the same temperatures exhibits negative deviations from Raoult’s law over the whole concentration range. The α functions of indium in the alloys show curves against NIn, suggesting the absence of the behavior of a regular solution.
The free energy of mixing at 1050 K has large negative values compared with ΔGid, and the peak value of ΔG shows −27.0 kJ/mol at about NIn=0.55. Heat of mixing shows very large negative values. The peak value of ΔH is −20.6 kJ/mol at about NIn=0.49.View full abstractDownload PDF (809K) -
Nobuo Kobayashi, Hiroyuki Ichinose1990 Volume 54 Issue 11 Pages 1228-1235
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe corrosion rate in a 0.5 kmol·m−3 NaOH aqueous solution of cold-rolled aluminum sheet was measured, and the results were analyzed from the point of view of the residual stress and rolling texture. For each total reduction (10-90%), which was applied to cold rolling, the specimens were equalized in initial thickness. The fixed reduction rate (Δh⁄h) and the fixed draught (Δh) were applied to the reduction per pass, and the initial orientation of the specimen and the surface character of the roll were varied. In the case of the reduction rate mode applied to the reduction per pass, the corrosion rate showed a non-monotonic increase; i.e. the curve has a maxima at 30 and 80% and a minimum at 50% total reduction. Contrary to this, in the fixed draught mode the corrosion rate reached a maximum value at 30% total reduction, and then decreased non-monotonically. Regardless of the difference in initial orientation, the corrosion rate showed the same behavior, but it became smaller as the crystal grain became larger. When cold rolling was performed on rolls with a rugged surface, the rolling texture showed a surface texture ((001)[1\bar10]) at 90% total reduction, and there was the correlation between residual stress and corrosion rate. In the case of the fixed draught mode applied to cold rolling, the residual stress decreased and the corrosion rate became smaller in the high domain of total reduction.View full abstractDownload PDF (2050K) -
Akira Sato, Yoshiaki Osawa, Goro Aragane1990 Volume 54 Issue 11 Pages 1236-1242
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA method of producing aluminum profile rods by the moldless upward continuous casting process using formers was investigated. Effects of the configuration of the former, the superheat of molten metal, and the upward withdrawal speed on the ratio of strand formation (the ratio of the diameter or the side of the cast strand to the nozzle diameter or the nozzle side of the former), the macrostructure, and the surface conditions of the cast strand obtained were examined.
Aluminum profile rods having various cross-sectional configurations and also longitudinal tapers could be produced by using formers made of refractory materials which determined the configuration of molten metal pillars formed on withdrawing upwardly. The former should be a “hot” one classified by Kostiegov et al. and its nozzle position should be lower than the molten metal surface by 5-10 mm. The cast strand was composed of columnar grains solidified completely unidirectionally. The ratio of cast strand formation was determined by the size of the nozzle, the superheat of the molten metal, the withdrawal speed, and the strand cooling intensity. The profile rods with no taper could be produced most easily when the ratio of strand formation was kept at around 90-95%.View full abstractDownload PDF (1636K) -
Masatomo Kamada, Masaaki Kohno, Youichi Tokunaga1990 Volume 54 Issue 11 Pages 1243-1249
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHigh chromium steel powder compacts are sintered in single-phase region of austenite (γ) or ferrite (δ) and two-phase region of ferrite/austenite (δ/γ) and the sintered compacts are subjected to the measurement of dimensional changes, in order to clarify the relationship between sintering shrinkage and matrix phase at sintering temperature.
The specimens sintered in δ-phase shrink much larger than that sintered in γ-phase, owing to high self-diffusibility of δ-phase. For the specimens sintered in a two-phase region of (δ/γ), the shrinkage rate increases with increase in amount of δ-phase. The shrinkage rate of the two-phase region sintered specimens is, at the same time, calculated by the law of mixture using the data for the specimens sintered in the single-phase regions of γ and δ. The comparison of the calculated and experimental values suggests an additional effect of (δ/γ) two-phase sintering on enhancement of the sintering shrinkage. This additional effect is associated with the preferential precipitation of δ-grains from the matrix/pore interface and the change in total area and type of grain boundaries.View full abstractDownload PDF (1970K) -
Takashi Arai, Toshiharu Kobayashi, Takehiko Itagaki, Atsushi Takei, Ak ...1990 Volume 54 Issue 11 Pages 1250-1255
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to obtain a ceramic barrier to prevent diffusion at the fiber/matrix interface of metal/metal composites, ZrCx coating on molybdenum plates was attempted by an activated reactive evaporation process in a Bunshah type ion plating apparatus. Layers of the Zr-C binary system were deposited on the molybdenum plates under a constant Zr vapor pressure (under a constant voltage and current at an electron beam melting) and various C2H2 pressures. The properties of these coatings were investigated, and the following results were obtained. (1) A series of compositions in the Zr-C binary phase diagram, from the α-Zr to γ-phase via the bi-component phase of (α-Zr+γ), were deposited when the C2H2 pressure increased from 0 to 11.3×10−2 Pa under a constant E. B. current of 0.7 A. By ESCA analysis, it was confirmed that the coating with a composition of (γ+Graphite) was deposited on the molybdenum plates. The hardness of the coatings and the lattice parameters of the α-Zr and ZrCx phases increased lineary with C2H2 pressure. (2) The lattice parameters of the as-deposited ZrCx phase deposited under the C2H2 pressures higher than 6.8×10−2 Pa were considerably larger than the value in the reference. Lattice parameters of the ZrCx phases decreased after annealing. While the lattice parameters of the ZrCx phase in some of the annealed coatings decreased to the reference value, that of the coating deposited under the highest C2H2 pressure (11.3×10−2 Pa) remained to be larger than it. The lattice parameter of the α-Zr phase in the coating deposited without supply of acetylene was almost equal to the reference value, both in the as-deposited and the annealed conditions. (3) While fine cracks appeared in the Zr-rich ZrCx coatings formed under low C2H2 pressure, they did not become so in the C-rich ZrCx coatings formed under high C2H2 pressure or in the bi-component coating with α-Zr formed under very low C2H2 pressure. (4) Grain sizes of α-Zr and ZrCx phases obtained from X-ray diffraction analysis showed a good relationship with C2H2 pressure.View full abstractDownload PDF (1209K) -
Yoshiki Tsunekawa, Hiroshi Harada, Masahiro Okumiya, Itaru Niimi1990 Volume 54 Issue 11 Pages 1256-1260
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThermal conductivity of thermal barrier coatings with gradient constituents, which are fabricated by plasma spraying, is experimentally measured and compared with the theoretical value derived from the rule of mixture in series.
Stainless steel (SUS310S) and Y2O3 stabilized ZrO2 (YSZ) powders were used as a spray material in low pressure plasma spraying (LPPS). The YSZ/SUS310S composite layers with gradient constituents were fabricated by LPPS with two powder feeders, the supplying rate of each spray material was then changed gradually during the spray process. Thermal conductivity of the sprayed layers was measured by a laser flash method at room temperature.
The sprayed YSZ/SUS310S layers show a layered structure, the YSZ content is, however, gradually decreased from the bottom of the layer to the top, macroscopically. Thermal conductivity of the layers with gradient constituents is expressed using an average volume fraction of YSZ. The measured thermal conductivity agreed well with the calculated value in the wide range of the average volume fraction. In order to fabricate the thermal barrier coatings with specified constituent profiles, LPPS can be utilized with a program-controlled powder feeding system and an established spray yield of each pre-mixed powder.View full abstractDownload PDF (1205K) -
Jianping Liu, Keijiro Nakasa1990 Volume 54 Issue 11 Pages 1261-1269
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe behavior of hydride peeling during hydrogen charging in sulfuric acid solution was investigated on the Ti-6Al-4V alloy specimens with different metallographic structures. In addition, an X-ray diffraction analysis was carried out to clarify the hydride formation process near specimen surface.
The amount of hydride peeling increased monotonically with increasing hydrogen charging time. In the specimens with coarse acicular α+β structure, the hydride peeled more severely, while in the specimens with granular α+β the amount of peeling was small. When the hydride peeling occurred stably, the surface of the specimens with coarse acicular α+β structure was almost composed of hydride, and the amount of hydride decreased sharply with increasing depth, x, to almost zero at x\fallingdotseq1 mm. In the specimen with granular α+β structure, on the other hand, the surface consisted of a mixture of hydride and α phase, and the amount of hydride decreased gradually with increasing depth. The peeled powder was almost hydride independently of structures. The reason for the larger peeling amount of the specimen with coarse acicular α+β seemed to be that the β phase with a large diffusion coefficient of hydrogen was divided by long and narrow α phases, and the hydrogen diffusion from the surface to the inside of the specimen was obstructed, i.e. hydride was formed only near the specimen surface, and the sharp gradient of internal compressive stress in the thickness direction due to volumetric expansion of hydride resulted in the large amount of surface peeling.View full abstractDownload PDF (3392K) -
Naoya Hasegawa, Masamichi Saito1990 Volume 54 Issue 11 Pages 1270-1278
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMagnetic and structural properties of microcrystalline Co-M-C (M: IVA-VIA) alloy films prepared by annealing sputter-deposited amorphous films were investigated. These new alloys were composed of Co-rich crystallites with grain diameters of several nanometers and M carbides. Except for Co-Cr-C films, these fine grain structures led to good soft magnetic properties. The low coercive force less than 60 A/m was maintained even after annealing at 973 K because of the suppression of grain growth by finely dispersed carbide particles. In addition, the highest saturation flux density of 1.6 T was obtained for Co-Zr-C and Co-Hf-C films. Although magnetostrictions of the films were negative for the most composition range, zero magnetostriction could be achieved by addition of Fe, Ni, Mn or Pd which stabilizes the fcc phase of Co. These new microcrystalline films are suitable for use in magnetic heads fabricated by the glass bonding process.View full abstractDownload PDF (1681K) -
Akihiro Miyazaki, Masaharu Tokizane, Teruhiko Inaba1990 Volume 54 Issue 11 Pages 1279-1283
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe mixture of elemental powder of Ti(70 at%) and Al(30 at%) was offered to a mechanical alloying process. The processed powder was vacuum hot pressed at 1173 K for 3.6 ks under 100 MPa. The compact having relative density of approximately 100% was obtained.
The results of X-ray diffraction, TEM observation and energy dispersive X-ray analysis indicated that the compact has an ultra-fine grain (average grain diameter=1.5 μm) structure consisting of Ti3Al intermetallic compound.
The compact showed a noticeable high compressive strength (0.2% proof stress=2065 MPa). However, its ductility was rather low (compressive fracture strain was about 5%).
During compressive deformation of the compact at 1173 K, a typical dynamic recrystallization which introduce a some extent of grain refinement was observed.
Moreover, the compact showed a very large m-value of 0.44 at 1173 K. Then, the compressive deformation of the compact at this temperature was presumably proceeded by superplastic flow which closely related to the dynamic recrystallization behavior.View full abstractDownload PDF (1439K) -
Kiyoshi Watanabe1990 Volume 54 Issue 11 Pages 1284-1290
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe permanent magnet properties and the temperature dependences of Fe-Pt-Nb ternary alloys were investigated by using a recording fluxmeter, a vibrating sample magnetometer and an X-ray diffractometer.
The excellent permanent magnet properties in the Fe-Pt-Nb system have been obtained by water-quenching from a temperature in the γ phase region and subsequent tempering at about 850-900 K in the γ1 phase region. A typical Fe-39.5 at%Pt-0.75 at%Nb alloy exhibits the highest value of a maximum energy product of 167 kJ·m−3, with a residual flux density of 1.05 T and a coercivity of 398 kA·m−1. These properties are superior to those of the basic binary Fe-Pt alloy. The composition range of the excellent permanent magnet properties of Fe-Pt-Nb ternary alloys spread out wider than that of Fe-Pt magnet alloys, so that the heattreatments could be controlled easily, and the reproducibility of the magnetic properties would be improved. As a Fe-38Pt-1Nb alloy exhibits the excellent rectangular hysteresis loops at 400 K as well as at 290 K, these magnet alloys have the stable temperature properties and show comparatively high Curie temperature.
It is presumed that the excellent permanent magnet properties of the Fe-Pt-Nb alloys originate from the existence of a constitutionally imperfect γ1 phase of the initial ordering state which induce the pinning of the magnetic domain wall.View full abstractDownload PDF (837K) -
Yoshimitsu Okazaki, Kiyoshi Ichikawa, Yuzo Hosoi1990 Volume 54 Issue 11 Pages 1291-1292
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (291K) -
Yoshiro Ito, Hisahiro Sakai, Yukio Ichinose1990 Volume 54 Issue 11 Pages 1293-1294
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (392K) -
Hirofumi Yoshimura, Kin’ichi Kimura, Masayuki Hayashi, Mitsuo Is ...1990 Volume 54 Issue 11 Pages 1295-1296
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (501K)
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