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Volume 57, Issue 11
Displaying 1-19 of 19 articles from this issue
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Kazuhito Kamei, Hisami Yumoto1993 Volume 57 Issue 11 Pages 1227-1234
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe electrodeposition behavior of Zn-Ni alloy whiskers from a sulfate bath has been studied by means of SEM, TEM and X-ray diffractmetry. The whiskers grow preferably under the low current density (1∼5×102 A/m2) and the low nickel bath content (about 10%). The structure of the whiskers is the type of γ-brass of which lattice parameter is about 0.9 nm. Since the whisker contains no dislocation, its growth mechanism should be similar to the Vapor-Liquid-Solid (VLS) mechanism that is able to explain the whisker formation from the vapour phase. In the electrodeposition of Zn-Ni alloy whiskers, the zinc hydoxide layer formed during the electrodeposition may play the role of the liquid layer in the VLS mechanism. The supporting electrolyte (Na2SO4) inhibits the electrophoresis and increases the viscosity of the bath, and the increasing the concentration of it promotes the growth of the whiskers extremely.View full abstractDownload PDF (3443K) -
Wen Huai Tian, Kousuke Harada, Reiji Nakashima, Takeshi Sano, Minoru N ...1993 Volume 57 Issue 11 Pages 1235-1243
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMorphologies and crystal structures of precipitates in L10-ordered TiAl containing carbon or nitrogen have been investigated in terms of transmission electron microscopy (TEM). During aging at temperatures around 1073 K after quenching from 1423 K, TiAl hardenes appreciably by the precipitation of carbide or nitride. The increment of yield strength due to the precipitation of carbide is larger than that obtained by the precipitation of nitride.
TEM observations revealed that needle-like precipitates, which lie only in one direction parallel to the [001] axis of the TiAl matrix, appear in the matrix and preferentially at dislocations. Selected area electron diffraction analyses have shown that the needle-shaped precipitate is of perovskite type, Ti3AlC or Ti3AlN (P-phase), which has not been expected from the accepted equilibrium phase diagram. The orientation relationship between the P-phase and the TiAl matrix is found to be (001)P\varparallel(001)TiAl and [010]P\varparallel[010]TiAl. By aging below 1073 K, long range ordering of carbon-vacancy and nitrogen-vacancy pairs in the perovskite carbide and nitride is formed and two variants of ordered domains coexist in a single needle thereby decreasing the accumulation of the anisotropic strain field around needle. By aging at higher temperatures or for a longer period at 1073 K, plate-like precipitates of Ti2AlC or Ti2AlN (H-phase) with a hexagonal crystal structure are formed on the {111} planes of the TiAl matrix. The orientation relationship between the H-phase and the TiAl matrix is (0001)H\varparallel(111)TiAl and [11\bar20]H\varparallel[\bar101]TiAl. The stability of P-phase decreases with increasing aluminum content in TiAl.View full abstractDownload PDF (2617K) -
Kunimasa Takeshita, Yoshinori Takezawa, Zhao Gaoyang1993 Volume 57 Issue 11 Pages 1244-1250
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThree alloys of Al-5.9 mol%Fe-1.3 mol%Ni, Al-5.3 mol%Fe-2.7 mol%Ni and Al-5.1 mol%Fe were rapidly solidified to ribbons by the planar flow casting method. The effects of nickel addition to Al-Fe alloy on the microstructure and mechanical property were investigated by examining the microstructures and mechanical properties of the as-solidified and subsequently annealed ribbons. As for the nickel-containing alloys, the coarsening of eutectic is retarded and the sum of volume fractions of intermetallic compounds increases with annealing.
The hardness, 0.1% proof stress and ultimate tensile strength of the nickel containing alloys consequently increase on annealing at 500 K for 7.2 ks, while those of the Al-Fe alloy decrease on the same annealing. It is found in all the alloys regardless of the annealing that the 0.1% proof stress σy0.1 (MPa) and ultimate tensile strength σTS (MPa) at room temperature are related to the ribbon hardness Hv as; σy0.1=2.45Hv and σTS(MPa)=167+2.13Hv respectively.View full abstractDownload PDF (1682K) -
Setsuo Aso, Michihiro Tagami, Shoji Goto1993 Volume 57 Issue 11 Pages 1251-1257
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFe-5%Cr-C system white cast iron can be taken as a composite containing M3C-type carbide and the pearlite matrix. The purpose of this investigation was to find a relationship between volume fraction of carbide and sand-erosion loss on the basis of rule of mixtures. The six kinds of specimens containing 2.4 to 6.5 mass% carbon were prepared by unidirectional solidification. The structure of each specimen was changed from hypo-eutectic to hyper-eutectic as the carbon increased, while the volume fraction of carbide also increased from 10 to 83 vol%. The sand-erosion test was carried out at two slurry temperatures (280 and 298 K) and at the rate of 7.7 m/s using a sample-rotating type apparatus. From the hardness test of these specimens it was indicated that both of the measured hardness and the calculated hardness increased as the carbide volume increased, but the calculated value was larger than the measured one. The total erosion loss of the specimen was mainly controlled by the erosion of the eutectic matrix structure. The erosion occurred at the beginning by phase-boundary corrosion in the eutectic matrix, therefore the eutectic structure which existed much phase boundaries, indicated poor erosion resistance. From the arrangement of sand-erosion data on the basis of rule of mixtures it was clarified that the sand-erosion behavior strongly depended on the structure and slurry temperature.View full abstractDownload PDF (1669K) -
Toshiya Kinoshita, Hiroshi Kubo1993 Volume 57 Issue 11 Pages 1258-1267
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to make clear the origin of the break-down of the linear elastic fracture mechanics for small cracks of ceramics, microscopic observation, using a differential interference microscope, was made for the stable crack growth developed at the fracture origin in hot-pressed Si3N4 samples under the stress field.
Three-point bending tests were carried out to investigate the relationship between intrinsic flaw size and strength of the Si3N4 samples. It was found that the linear elastic fracture mechanics holds only within 50 μm in the equivalent crack length.
Knoop flaws were introduced, before the three-point bending test, on the specimen surface to check the microscopic fracture machanism: For the flaws larger than the critical crack size (>50 μm), the fracture took place after stable crack growth, while for the smaller flaws than the critical one (<50 μm), the fracture occurred with no stable crack growth.
It is concluded from the above experimental results that the microscopic fracture originates in the combination of the main crack and microcracks and the break-down of the linear elastic fracture mechanics in small cracks occurs due to the microcracks generated in the proxmity of the crack-tip of the main crack, which causes the stress relaxation corresponding to the mechanism of plastic deformation in metals.View full abstractDownload PDF (3549K) -
Norio Maruyama, Masae Sumita, Kouzou Nakazawa1993 Volume 57 Issue 11 Pages 1268-1274
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study has been made of the role of silicon carbide (SiC) particles in the fatigue strength and fretting fatigue strength at high cycles using powder metallurgy 2024-T6 Al metal matrix composites reinforced with 20 vol%. SiC particles with the mean sizes of 2 and 16 μm. The 107 cycles plain fatigue strengths of the composites were within the values estimated on the basis of the change of the elastic modulus and the ultimate tensile strength due to the reinforcement. The 107 cycles fretting fatigue strengths in the composites were about 30% higher than those estimated. This suggested that the increase in fretting fatigue strength in the composites was probably due to low stress concentration at the fretted area and crack growth resistance caused by avoiding the SiC particles at low stress intensities.View full abstractDownload PDF (1149K) -
1993 Volume 57 Issue 11 Pages 1274
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPlease see pdf. Wrong:[in Japanese] Right:[in Japanese]View full abstractDownload PDF (79K) -
Hisaki Okabayashi1993 Volume 57 Issue 11 Pages 1275-1280
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe following relation given in the previous report is also in the neighbourhood of 4 K for iron and BCC iron alloys:
(This article is not displayable. Please see full text pdf.)
\ oindentwhere Gic is the critical strain-energy release rate, T the testing temperature, and d is the grain size (mm).
The results obtained in the present study indicate that (1) Gic extrapolated to 0 K, i.e. G0, depends upon solute nitrogen and carbon contents as a fuction of ([C]+4[N])at.%; (2) G0 values are 1.1 kJ/m2 when the nitrogen and carbon contents are zero or under the tempered condition, and (3) the temperature dependence of Gic, i.e. 1⁄T0, increases with increasing nickel content, while it decreases with increasing nitrogen content.View full abstractDownload PDF (427K) -
Kuniomi Wase, Yosuke Kishi, Yoichi Maru1993 Volume 57 Issue 11 Pages 1281-1287
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSExtraction behavior of cobalt and sodium (abbreviated to Co(II) and Na, respectively) with Versatic Acid 10(abbreviated to VA10 and its chemical formula is abbreviated to RH) was investigated by experimentally obtaining phase equilibria in the VA10-Co(NO3)2-NaOH-H2O system and in the VA10-Co(NO3)2-H2O system at 298 K. The results obtained are as follows.
The distribution ratio of Co(II) is very small in the case of VA10-Co(NO3)2-H2O system. In the case of the VA10-Co(NO3)2-NaOH-H2O system, on the other hand, Co(II) is preferentially extracted to Na in the narrow pH region. After the extraction of Co(II) is completed, Na starts to be extracted as pH value becomes higher. Extracted species of Na can be identified as RNa and that of Co(II) is inferred to be either in the form of monomer or dimer. The extractant, RH is hardly dissolved in the aqueous phase in the pH region in which the extraction of Co(II) is dominant. On the contrary, in the pH region in which the extraction of Na becomes dominant, the RH concentration in the aqueous phase rapidly increases. Based on the results thus obtained, the solubility surface and tie lines between organic and aqueous phases were constructed on a composition tetrahedron of the RH-Co(II)-Na-H2O simplified system. It is shown that an overview of extraction behavior of Co(II) and Na with RH can synthetically be understood from this composition tetrahedron.View full abstractDownload PDF (892K) -
Kazuo Kasahara, Masao Takeyama1993 Volume 57 Issue 11 Pages 1288-1292
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe oxidation behavior of Ti-52 mol%Al in a temperature range of 1000 to 1273 K was examined by using samples with different surface preparations. At temperatures below 1170 K, the oxidation resistance increases with increasing surface roughness, and the mass gain of the sample with sand-blasted surfaces is smaller by an order of magnitude than that of the sample with electropolished surfaces at 1000 K. The drastic increase in oxidation resistance is caused by the formation of protective aluminum-rich oxide layers on the surfaces at an early stage of oxidation, which is presumably due to a rapid diffusion of aluminum atoms form the bulk to the surface through the work-hardened layer introduced by the abrasive treatment on the surface. At higher temperatures above 1170 K, however, little difference in the mass gain is observed among the samples with different surface preparations. The titanium-rich oxide is dominantly formed on the sample surfaces, regardless of the surface preparations, leading to no positive effect of surface roughness on the oxidation resistance.View full abstractDownload PDF (2200K) -
Motoshige Hibino, Takehiko Mae, Hisahiro Sakai, Satoshi Sunada, Koichi ...1993 Volume 57 Issue 11 Pages 1293-1300
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of Ga content on the characteristics of precipitation for Al-0.9 mass%Mg2Si alloys was investigated by the measurements of DTA curves of aging, transmission electron microscopy, and electron diffraction of precipitates. Furthermore, the relationship between the precipitation behavior and corrosion resistance for the alloys was estimated by means of an electrochemical measurement of the polarization curves, immersed corrosion tests, and scanning electron microscopic observations of the corroded surfaces for the alloys with various phases in a dilute HClO4 solution.
The main results obtained are summarized as follows:
(1) The effect of the added Ga on the characteristics of precipitation occurs mainly in G.P. II zone, and its initiation temperature of Mg2Si precipitation is lowered with increasing Ga content in the alloys. However, the distribution and composition of precipitates with transition and equilibrium phases are independent of Ga content.
(2) The activation potentials (Eact.) of Al-0.9 mass%Mg2Si alloys in a dilute HClO4 solution decrease in the order of super saturated solid solution>equilibrium phase>transition phase. On the contrary, the anodic current densities (log(Ia)) of the alloys under a potentiostatic condition increase in the order of super saturated solid solution<equilibrium phase<transition phase regardless of the Ga content.
(3) The corrosion of the alloys is uniform at the super-saturated solid solution phase. However, the corrosion of the alloys containing Ga is enhanced by a selective dissolution of Mg or Al from the boundary layers of the alloys. On the other hand, galvanic corrosion occurred between the Mg2Si precipitates and a matrix phase for the alloys with the transition and equilibrium phases regardless of the Ga content, and the Mg2Si precipitates act as an anode. On the contrary, the matrix phase acts as a cathode. The selective dissolution of Mg from the precipitates is observed on the corroded surfaces.View full abstractDownload PDF (2034K) -
Akihiro Makino, Yasuo Hayakawa1993 Volume 57 Issue 11 Pages 1301-1309
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFe-Hf-O films with solute contents of 2.1 to 22.7 at.%Hf and 7.8 to 41.6 at.%O were prepared by a r.f. magnetron sputtering apparatus in Ar+O2 atmosphere, and their microstructures, magnetic properties and electrical resistivities (ρ) were investigated. A structure composed of an amorphous and a bcc phases is found to be formed in the compositional range of 10 at.%≤Hf and 15≤O≤36 at.% for Fe-Hf-O films. The fraction of the amorphous phase containing a large amount of O which produces high ρ, increases and the size of the bcc grain decreases with increasing Hf content. The crystallization of the amorphous phase takes place through two stages, at the lower- and higher-temperature above 730 K, due to the precipitation or growth of the bcc phase and the oxide phases containing Fe or Hf, respectively. The films with the compositional range of (O/Hf)=3.2∼4.0 in the as-deposited state show low coercivities of 30∼100 A/m and also excellent soft magnetic properties after annealing at 673 K which cause the substantial change of the as-deposited structure. Fe54.9Hf11O34.1 film annealed at 673 K for 21.6 ks in a rotating magnetic field of 160 kA/m exhibits a low coercivity (Hc) of 64 A/m, a high magnetization (Bs) of 1.2 T and a high permeability (|μ|) of 1800 at 50 MHz due to its high electric resistivity (ρ) of 8×10−6 Ω·m, the value of |μ| is superior to those for known soft magnetic materials. It is therefore expected that the films with good soft magnetic properties in addition to high ρ is useful for micro magnetic devices at the high frequency range.View full abstractDownload PDF (1927K) -
Kiyoshi Ichikawa, Masakazu Achikita1993 Volume 57 Issue 11 Pages 1310-1316
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn investigation was made on the microstructure and the electrical and mechanical properties of dispersion-strengthened (DS) coppers compocast at 25 rev/s and with the addition of fine ceramic particles of VB, TaB2, WC, TaC, SiC, TiN, Al2O3, and ZrO2. Homogeneous distribution of all the particles except Al2O3 and ZrO2 was observed in the compocast DS coppers. In the compocast boride particles-dispersed coppers, with the increased addition of 1 to 5 mass%TaB2, the electrical conductivity decreased from 101 to 94.2%IACS; the hardness increased from Hv64.9 to Hv73.9; the ultimate tensile strength increased from 137 MPa to 229 MPa; the elongation value decreased from 47.1% to 33.0%; and the reduction of area decreased from 70.5% to 31.4%. The compocast 10 mass%WC-dispersed coppers were thermomechanically treated by hot extrusion, cold drawing and annealing. The hardness of the hot-extruded and cold-drawn DS coppers increased up to Hv138, which was twice the value of Hv79.6 of the as-compocast DS copper. The hardness of the hot-extruded, cold-drawn and annealed DS coppers decreased gradually with increasing annealing temperature except when a fluctuation existed. In the 1 mass%WC-dispersed coppers compocast with addition of alloying elements of 1 to 2 mass%Al, Ni and Fe, the electrical conductivity decreased exponentially with the increase in atomic percent of the alloying elements.View full abstractDownload PDF (1474K) -
Hiromichi Nakata, Takao Choh1993 Volume 57 Issue 11 Pages 1317-1324
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe in situ formation and dispersion behavior of carbide particles in a liquid aluminum alloy has been investigated to develop a novel technique utilizing the spontaneous reaction among materials for fabricating aluminum matrix composites. Titanium, zirconium and hafnium carbide were in situ generated by the reaction between a liquid aluminum alloy containing the group IVa element and Al4C3 particles. However, the reaction rate decreased in the order of titanium, zirconium and hafnium. On the other hand, the amount of in situ formed carbide in the aluminum alloy system containing group Va element increased in the order of vanadium, niobium, tantalum depending on the thermodynamical stability of the carbide of each element.
The effects of processing variables, such as the kind and size of raw carbide, the alloying element and processing temperature on the in situ formation rate of TiC and ZrC have been estimated quantitatively. The experimental results were analyzed by the in situ reaction kinetic model based on the assumption that the overall reaction rate was controlled by both the interfacial reaction and the diffusion through the layer of the generated carbide particles. At the initial stage of the formation of TiC, the interfacial reaction rate is mainly controlling step. However, the process is gradually controlled by the diffusion at the later stage. Owing to the formation of fine circular carbide surrounding raw carbide particles, the in situ reaction rate decreased radically in the Al-Zr or Al-Hf system.View full abstractDownload PDF (2014K) -
Deug Gyu Kim, Junichi Kaneko, Makoto Sugamata1993 Volume 57 Issue 11 Pages 1325-1332
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn-situ particulate composites can be manufactured from aluminum-oxide system by mechanical alloying followed by the hot consolidation and heat treatment. Powders of transition metal oxides of standard free energies of formation lower than that of SiO2; V2O5, Nb2O5 and Ta2O5 were mechanically alloyed with pure aluminum powder by a high energy ball mill under an argon atmosphere. P/M materials were fabricated from mechanically alloyed powders by cold pressing, vacuum degassing and hot extrusion. Two kinds of process control agent, methanol and graphite were used for mechanical alloying. The solid state reaction of aluminum-oxide systems was studied by X-ray diffraction. In case of graphite as process control agent, formation of Al4C3 and thermite reaction occur faster than in case of methanol. It is shown by X-ray diffraction that P/M materials consist essentially of aluminum-transition metal alloy matrix with dispersion of Al2O3 after heating at 873 K for 10 h. Upon heating of P/M materials at 873 K, the hardness increased due to resulted formation of transition metal aluminides.View full abstractDownload PDF (2320K) -
Kazuhiro Tsuchiya, Yasuo Shimizu, Kazuhiko Sakaki, Mototaro Sato1993 Volume 57 Issue 11 Pages 1333-1338
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis study describes the theoretical mechanism with regard to stock removal of magnetic abrasive polishing and experimental analysis with regard to the various factors that influence upon stock removal, using two types of experimental equipments of surface polishing and cylindrical polishing. The following results were obtained. (1) Polishing mechanism was theoretically analyzed, and the effects of its controlling factors were clarified separately. (2) Various factors, such as exciting current, abrasive charge amount, abrasive particle size, work gap and magnetic pole shape, which control the magnetic flux density, were investigated experimentally and the effects of each factor upon the polishing efficiency were clarified.View full abstractDownload PDF (904K) -
Kunimasa Takeshita, Kazuhiko Matsui1993 Volume 57 Issue 11 Pages 1339-1345
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTitanium was brazed with aluminum by varying the filler metal thickness and brazing time in order to change the microstructure of the joint. The layer of intermetallic compound Al3Ti, the thickness of which increases proportionately with the increase in square root of brazing time, is formed at the interface between filler and base metals.
The aluminum layer thickness of 25 μm affords the joint of highest tensile strength, the value of which is 250∼280 MPa. The growth of Al3Ti layer thicker than 10 μm causes the drop in tensile strength of joint.
A finite element analysis considering various fracture criteria is also carried out. The experimental results is discussed in comparison with the results of calculation.View full abstractDownload PDF (1422K) -
Hiroshi Kimura, Shin-ichi Kobayashi1993 Volume 57 Issue 11 Pages 1346-1351
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA novel P/M processing of functionally gradient materials is developed, from which one can select the combination of the constituents with greatly different densification rate and then realize full densification. This processing consists of pulse-electric discharge consolidation combined with a temperature slope control technique using a specially designed die in outer shape. For powders of the amorphous TiAl/3 mol%Y2O3-PSZ system, the lowest consolidation temperature necessary to obtain a full density compact increases from 1242 K to approximately 1700 K with increasing molar ratio of PSZ in the case of an applied stress of 49 MPa. We set up a test condition of a temperature profile and a constant sintering rate along a gradient composition, using a die with two different diameters showing a temperature increase of more than 700 K with in a width of 7 mm. Then, we can synthesize a 5-layered functionally gradient material of the intermetallic TiAl/PSZ system, having full densification everywhere in an overall cross-section without any discontinuity. This material shows a high vickers hardness of 650 DPN at a layer of γ-phase TiAl with α2(Ti3Al), synthesized by crystallization from an amorphous phase, and increases up to 1560 DPN at a PSZ layer according to a mixture law.View full abstractDownload PDF (1011K) -
Yutaka Yanaba, Won-Seung Cho, Koji Hayashi1993 Volume 57 Issue 11 Pages 1352-1359
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to investigate whether the fracture of high strength Si3N4-based ceramics does occur or not from one or one set of observable microstructural defect acting as the fracture source, the fracture surfaces of the fragments for each 18 test piece of four kinds of high strength Si3N4-based ceramics supplied by three manufacturers were precisely observed by using SEM.
The results obtained were as follows. (1) It was confirmed for all kinds of specimens that the fracture always occurred from one or one set of observable microstructural defect as the fracture source, even when the strength was very close to the attainable flexural strength. (2) The above results indicate that the average flexural strength can be further increased even for high strength Si3N4-based ceramics by decreasing the amount and size of the microstructural defects and that the effects of variables on the strength should be analyzed by taking into consideration of the microstructural defect which acted as the fracture source.View full abstractDownload PDF (2610K)
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