All issues
Volume 51, Issue 2
Displaying 1-11 of 11 articles from this issue
- |<
- <
- 1
- >
- >|
-
Yoshihiro Takahara, Kazunari Hatade, Hidehiko Matsuda1987 Volume 51 Issue 2 Pages 95-101
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe structural relaxation and crystallization processes of amorphous Fe79B16Si5, have been studied by electrical resistivity, Mössbauer spectroscopy and X-ray measurements. From the electrical resistivity measurement, it was found that the structural relaxation consisted of two separate processes which were characterized with relaxation times τ1 and τ2 (τ1<τ2). The analysis of Mössbauer spectra showed that the change in the isomer shift and in the peak position in the distribution of magnetic internal field occurred at/near the relaxation times during isothermal annealing; the former took place at the time τ1 and the latter did near both τ1 and τ2. The X-ray diffraction experiment made clear that the crystallization proceeded in such a way that α-Fe crystalline phase containing Si and/or B atoms appeared first and subsequently the residual amorphous phase decomposed into Fe2B and α-Fe phases.View full abstractDownload PDF (912K) -
Takatoshi Ogawa, Keizou Ohnishi, Tadashi Momono, Toshihei Misawa1987 Volume 51 Issue 2 Pages 102-110
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDisintegration of metal hydride powder during the repeated hydriding and dehydriding cycles has been a big problem which retards the practical application of metal hydrides. In order to solve this problem, microstructure-controlled LaNi5-Ni eutectic alloys have been studied and a promising alloy has successfully been developed. Alloys of hypo-eutectic, eutectic and hyper-eutectic compositions were melted by both arc-melting and unidirectional solidification. Resistance to disintegration of these alloys was compared with respect to the morphology of solidified structure. The results are as follows.
(1) Primary melt (as arc-melted alloy) of any composite LaNi5-Ni alloys can be readily obtained by arc-melting.
(2) Only the hyper-eutectic alloy among the primary melts shows high resistance to disintegration.
(3) In a relatively wide range of chemical composition, desired microstructure-controlled alloys can be obtained, if unidirectional solidification is properly supplied.
(4) The concentration of absorbed hydrogen decreases in the order of hypo-eutectic, eutectic and hyper-eutectic with or without unidirectional solidification. However, these values for the unidirectionally solidified alloys are much greater than those obtained for the primary melts.
(5) The unidirectionally solidified eutectic and hyper-eutectic alloys showed high resistance to disintegration.
(6) The differences in the concentration of absorbed hydrogen and the disintegration resistance between the primary melts and the unidirectionally solidified alloys are closely related to the morphology of solidified microstructure.View full abstractDownload PDF (2961K) -
Takatoshi Ogawa, Toshihei Misawa, Keizou Ohnishi1987 Volume 51 Issue 2 Pages 111-117
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt was shown in a previous report that the microstructure-controlled LaNi5-Ni eutectic alloy was a promising countermeasure for the disintegration of LaNi5 hydride. In the present study, the hydriding and dehydriding characteristics have been investigated for both arc-melted and unidirectionally solidified alloys of hypo-eutectic, eutectic and hyper-eutectic compositions. The results are as follows.
(1) The activation of the primary melts (as arc-melted alloys) needs ten hydriding-dehydriding cycles, whereas all the unidirectionally solidified alloys are easily activated by the four cycles.
(2) The rates of hydriding and dehydriding decrease in the order of hypo-eutectic, eutectic and hyper-eutectic with or without unidirectional solidification. However these values for the unidirectionally solidified alloys are much greater than those for the primary melts.
(3) Regardless of solidification structure, the concentration of absorbed hydrogen decreases with increase of Ni content. The effect of Ni content on the absorbed hydrogen concentration depends upon thickness of the specimen, if the alloys were the primary melts. However, this tendency is not observed in the unidirectionally solidified alloys.
(4) The hydrogen absorption and dissociation isotherms (PCT curves) of the unidirectionally solidified alloys show a smaller hysteresis and a distinct plateau compared with the primary melts.
(5) The effect of alloy composition on the equilibrium pressure of hydrogen absorption is different between the primary melts and the unidirectionally solidified alloys. The difference can be explained in terms of deviation from the stoichiometry of LaNi5 for the primary melts and in terms of lattice strain in the LaNi5 phase for the unidirectionally solidified alloys.View full abstractDownload PDF (1425K) -
Yasuo Uchiyama, Masayuki Hasaka, Hideto Koga1987 Volume 51 Issue 2 Pages 118-123
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo elucidate the formability of hot dip Zn-Al-Si alloy coated steel sheet, a cold rolled steel sheet was hot dipped in three Zn-Al-Si baths containing 10, 30 and 50 mass%Al, respectively, and 2 mass%Si to each Al content. These sheets were, then, tension tested or bend tested to 180° by an Instron type tension machine under a crosshead speed of 0.017 mm·s−1.
In the case of Zn-10 mass%Al-0.2 mass%Si bath, the coating has only a Zn-Al alloy layer which consists of Al-rich dendrites and Zn-rich interstices. In the case of Zn-30 mass%Al-0.6 mass%Si and Zn-50 mass%Al-1.0 mass%Si baths, an intermetallic compound layer is formed adjacent to the substrate and followed by the alloy layer. Many intermetallic compound particles were found in the alloy layer. Etching with 3%HF aqueous solution revealed that the compound layer is subdivided into two layers and that the phase of the compound layer is different from that of the particles.
The formation of Zn-Al-Si alloy coating on the cold rolled steel sheet causes the increase of yield strength. On the other hand, ultimate tensile strength is unchanged, and the work-hardening exponent, the fracture elongation and the plastic-strain ratio decrease generally. The last three valuses also decrease with the increase of the Al content. Thus the formability of the hot dip Zn-Al-Si alloy coated steel sheet depends mainly on the Al content. In the case of the highest Al content, bending to 180° causes the coating to peel off markedly. This phenomenon accounts for the formation of the compound layer, and as the thickness of this layer increases, the formability of the coated steel sheet deteriorates. The deteriorating effect of the compound layer is greater in the case of Zn-Al-Si coating than in the case of Zn coabng.View full abstractDownload PDF (1410K) -
Shinichi Nakamura, Akio Fuwa1987 Volume 51 Issue 2 Pages 124-130
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn this investigation, the transpiration-mass spectrometer system, whose development was previously reported, has been improved and upgraded for better sensitivity and detectability by provision of molecular beam chopping device, new properly designed-skimmer orifice, shorter geometric arrangement between beam-origin and beam-detector and higher evacuation pumping system installation Particularly, the chopping system is being incorporated into this system, in order to differentiate the molecular beam of gaseous specimen molecules from residual gaseous molecules, thereby increasing the accuracy and improving the detectability. After these improvements, compared with the previous system, the sensitivity has been increased as much as 100 times and detection of about ten parts per million has been attained.
Using this improved system, vapor species and pressure of selected sulphides, GeS, SnS and CdS, have been measured by combining the conventional transpiration vapour pressure measurement method and the mass spectrometer for species identification. The resultant vapourization reactions and vapour pressures are as follows:
(This article is not displayable. Please see full text pdf.)
\ oindentThese results are in good agreement with other research results.View full abstractDownload PDF (964K) -
Shusaku Yao, Hisayuki Kaku, Takashi Nakamura1987 Volume 51 Issue 2 Pages 131-137
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAg-Zn alloy film specimens prepared by electrodeposition and diffusion annealing were exposed at 303 K and 353 K to N2-O2 atmospheres containing 1 vol% H2S and of 2-90% relative humidity.
Corrosion product layers on the specimens after exposure were investigated using AES, XPS and HEED.
The results were summarized as follows.
(1) It was found that the corrosion product layers on Ag-Zn alloy films containing more than 34.0 mass%Zn mainly consisted of Ag2S, ZnS and ZnO. ZnO and thin ZnSO4 layers were suggested to coexist together.
(2) The corrosion product layer on an electrodeposited Ag-Zn alloy film containing 19.2 mass%Zn mainly consisted of Ag2S and ZnO. ZnO and thin ZnSO4 layers coexisted together in the same way as in alloy films containing more than 34.0 mass% Zn.
(3) CuS whisker was found locally in the corrosion product layers on electrodeposited Ag-Zn alloy films.
(4) HEED patterns indicated the presence of Ag2S, β-ZnS, Ag2SO4, ZnSO4 and ZnO adhering to the Ag-Zn alloy.View full abstractDownload PDF (1166K) -
Seiichi Iwata, Naoki Yamamoto, Nobuyoshi Kobayashi1987 Volume 51 Issue 2 Pages 138-141
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis paper deals with a problem encountered during the development of a new gate electrode structure for MOS VLSI (Metal-Oxide-Semiconductor Very Large Scale Integrated Circuits), namely, the increase in contact resistance between the two layers in a Mo/poly Si gate electrode structure after annealing at around 1273 K. This study was carried out by using ESCA (Electron Spectroscopy for Chemical Analysis) to understand the above phenomenon and find the means to prevent this contact resistance increase.
It was found that (1) the formation of Si oxide at Mo/poly Si interface was the cause of the increase in contact resistance, (2) the O (oxygen) necessary for this oxide formation was supplied from the Mo in contact with the poly Si, and (3) the oxide formation can be prevented by the addition of Si to the Mo, allowing the Si atoms to bond with the O atoms inside the Mo layer but not at the Mo/poly Si interface.View full abstractDownload PDF (583K) -
Takao Yamazaki, Mototaro Sato1987 Volume 51 Issue 2 Pages 142-147
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe finite element method has been applied to analysis of the cutting mechanism in aluminum single crystals and bicrystals. The program developed for this study includes the effect upon the plastic anisotropy of the crystal, using r-values of the crystal as input data.
The results are as follows:
(1) The calculated values of the specific cutting force Ks showed a good qualitative agreement with the experimental values. The results suggest that the finite element method is useful for the analysis of the cutting mechanism in an anisotropic material.
(2) The plastic anisotropy of the crystal had clearly an effect on the propagation of the plastic deformation in the shear zone.
(3) The grain boundary is an important part as the plastic restraint or the stress concentratton.View full abstractDownload PDF (911K) -
Tuneo Ohkoshi, Yukihiro Isoda, Syunji Ichida, Katashi Masumoto, Isao N ...1987 Volume 51 Issue 2 Pages 148-156
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSlip casting is one of the techniques used to produce ceramics, silisides and carbides with a complex shape. In this investigation, the effects of Fe, which contaminates pulverized CrSi2, on the relationship between slip viscosity and pH, the density of green state and the thermoelectric property of the sintered CrSi2 have been examined. The following are the results obtained.
The Fe content in CrSi2 powder increased linearly with increasing time of ball-milling. After 8.85×105 s of milling, Fe of 2.3 mass% was introduced to the powder, an average particle size of which was 1.05 μm. The slip viscosity increased and the apparent density of the green sample decreased with the Fe content. However, since the Fe acted as a sintering accelerator, the density of sintered CrSi2 was increased. The thermoelectric power α, the electrical resistivity ρ and the power factor α2⁄ρ of the sintered CrSi2 were lower than those of high purity one at room temperature by about 21%, 30% and 11%, respectively. When the temperature difference was 800 K, however, the effective maximum power of the CrSi2 was only a few percent lower than that of the high purity one and was independent of the Fe content in the CrSi2 powder. Therefore, when the slip casting technique is applied to production of CrSi2 powder, it is not necessary to remove the contaminating Fe,and CrSi2 thermoelectric materials can thus be produced easily. As an application of the technique, sintered CrSi2 caps with straight and complex shapes have been manufactured by way of trial.View full abstractDownload PDF (2608K) -
Toshiki Kabutomori, Takatoshi Ogawa, Kunio Teshirogi, Keizo Ohnishi1987 Volume 51 Issue 2 Pages 157-164
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of Mm substitution for Ca and Al substitution for Ni on the hydrogen absorption- desorption properties in the CaNi5 system were investigated by measuring the pressure-composition-isotherms. The results are as follows.
(1) Hydrogen dissociation pressures of the Ca1−xMmxNi5−yAly system increase with increasing x and decrease with increasing y.
(2) Enthalpy changes ΔH of hydride formation of the Ca1−xMmxNi5−yAly system increase with increasing x and decrease with increasing y. It has been recognized that there is a good correlation between the enthalpy change and the radius of interstitial hole of the crystal in this system.
(3) The substitution of Al for Ni in the CaNi5 compound leads to decrease in hydrogen absorption capacity. The concentration of absorbed hydrogen in the CaNi4.73Al0.3 is 40% lower than that in the CaNi5.15.
(4) The substitution of Al for Ni in the Ca1−xMmxNi5 system drastically improved the hysteresis in pressure-composition-isotherms of hydrogen absorption-desorption. This trend is more distinct in Mm rich alloys.View full abstractDownload PDF (1512K) -
Seiichi Iwata, Naoki Yamamoto1987 Volume 51 Issue 2 Pages 165-166
Published: 1987
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (337K)
- |<
- <
- 1
- >
- >|