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Volume 56, Issue 5
Displaying 1-19 of 19 articles from this issue
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Nobuhiko Kunitomi1992 Volume 56 Issue 5 Pages 487-493
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe crystallisation process of an amorphous ferromagnet Fe77.5B15Si7.5 has been accurately observed by means of the real time measurement of the magnetic moment which is induced during the course of crystallisation. The experiments made at temperatures between 773 and 733 K have revealed that the crystallisation occurs in two stages with the respective incubation times. The results are well fitted by a modified Johnson-Mehl-Avrami equation, which is improved to take the incubation period and the two-stage crystallisation process into account. Four characteristic periods, the incubation and relaxation times for the two stages, have been obtained by this fitting. The activation energy for each period has a value a little less than 4 eV, which is larger than the activation energies for the ordinary atomic diffusion phenomena. This implies that the atomic diffusion responsible to the crystallisation is not ordinary one but the one which needs extra energy.View full abstractDownload PDF (1021K) -
Shigeru Aoki1992 Volume 56 Issue 5 Pages 494-501
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMorphology of thermally induced oxide precipitates (SiOx, x=∼2) in Czochralski-grown Si crystals are investigated using transmission electron microscopy.
When the annealing temperature is 800 and 900°C, morphology of oxide precipitates is of a sqare-plate having the {100} habit plane with ⟨110⟩ sides and a column-like structure in it.
When the annealing temperature is 1000°C and the oxide precipitation rate is fast, the direction of dendritic growth is ⟨100⟩ in the Si matrix and top of the branch has a ⟨110⟩ facet. When the oxide precipitation rate is slow, the direction of the dendritic growth is ⟨110⟩.
These precipitates are amorphous SiO2. Their morphology is determined by either of these formation mechanisms: the Si matrix prescribes the shape of the precipitates (Si matrix negative crystal mechanism), or the interstitial oxygen grows to plate-like precipitates on the dislocations.View full abstractDownload PDF (4203K) -
Taiji Hoshiya, Fumiki Takada, Masao Omi, Ichiro Goto, Hiroei Ando1992 Volume 56 Issue 5 Pages 502-508
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTransformation properties and deformation behavior of Ti-Ni shape memory alloys which were irradiated at 323 and 520 K up to a maximum fast neutron fluence of 1025 m−2 and subsequently annealed above 523 K, were examined by electrical resistance measurements and tensile tests. When irradiation was performed at 323 K, Ms temperature of irradiated specimens abruptly decreased at a dose over 10−2 dpa. This shows that the irradiation has a great influence on transformation properties of specimens. After post-irradiation annealing above 523 K, the Ms temperature of specimens which were irradiated with a dose of 10−1 dpa, increased to that of unirradiated ones. When irradiation was performed at 520 K, the decrease in Ms temperature was negligibly small regardless of the magnitude of damage. It is clear that at irradiation temperature of 520 K the irradition has no influence on transformation properties of Ti-Ni alloys.
In the Ti-Ni alloys two conflicting processes take place during irradiation: disordering and ordering. The migration of vacancies is enhanced by thermal activation and ordering becomes predominant over the disordering and restoration phenomena occur. The phenomena can be described as a function of temperature, displacement and displacement rate by the theory of order-disorder transformation under irradiation. It is confirmed that the threshold temperature at whith the restoration phenomena take place is about 520 K.View full abstractDownload PDF (992K) -
Shigeoki Saji, Kazuhide Matsumoto, Toshiya Shibayanagi, Tohru Yamasaki ...1992 Volume 56 Issue 5 Pages 509-516
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPowders consisting of amorphous Al2O3 and Al-Ti-O-N phases were prepared from Al-12.4 at%Ti mixed powders by mechanical alloying in an atmosphere containing oxygen and nitrogen, and crystallization process upon annealing in the amorphous powders was investigated by means of X-ray diffraction, DTA, SEM and TEM (HREM). Al3Ti was detected after annealing for 3.6 ks in the temperature range of 673 to 1273 K and crystal growth of Al3Ti was accerelated at about 1073 K and declined gradually with increasing temperature. Al3Ti was not detected after annealing above 1373 K. γ-Al2O3 was detected after annealing ranging from 1123 to 1373 K. The crystallization temperature of γ-Al2O3 was about 1120∼1180 K and the apparent activation energy for crystal growth of γ-Al2O3 was 317 kJ/mol. Above 1223 K, the formation of α-Al2O3 and TiN proceeded preferentially. AlN was formed at temperatures above 1373 K. The size of the various crystalline phases in the annealed powders was about 5∼30 nm. No melt phase was observed during annealing at temperatures below 1573 K.View full abstractDownload PDF (2111K) -
Takahiro Kaneyoshi, Teruo Takahashi, Yukinobu Hayashi, Muneyuki Motoya ...1992 Volume 56 Issue 5 Pages 517-523
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe mixture of elemenatal powders of Cu, Al(14 mass%) and Ni(4 mass%) was offered to a mechanical alloying (MA) process. The compact of the MA powder having a relative density of above 99.5% was prepared by hot isostatic press (HIP) at 1123 K for 3.6 ks under 196 MPa. A Cu-Al-Ni shape memory alloy was obtained by solution treatment of the compact.
The results of X-ray diffraction indicated that crystal structure of the compact is consisting of γ′1 and β′1 martensites. The compact had a fine grain structure and the grain size decreased with the MA processing time. The minimum average grain size was 2 μm for 144.0 ks MA.
The compressive strength of the compact was twice as high as that of the melted sample in spite of the almost same values of hardness and ductility. The grain boundary cracking which occurred in the melted sample was suppressed.
The results of DSC indicated that the peak width and height are broadened and lowered, respectively. The martensitic transformation temperature (Ms) of the compact decreased with the MA processing time and depended linearly upon the average grain size. This may be caused by the fact that constraints among grains enhanced by grain refinement suppress the martensitic transformation.View full abstractDownload PDF (2207K) -
Yoshito Takemoto, Moritaka Hida, Akira Sakakibara, Norihide Nishida1992 Volume 56 Issue 5 Pages 524-530
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDiffusion heat-treated Ti-20 mass%Mo (DHT) alloys were prepared by titanizing to improve the ductility, and tested in tension. The DHT alloy had a diffusion layer about 120 μm in thickness. The quenched DHT alloy was deformed by twinning in the surface layer and by slip in the interior. Many cracks were generated over the surface of the aged specimen during testing, but the propagation of these cracks were prevented at the interface between the titanized surface layer and the interior. Both the quenched and the aged DHT alloys were elongated well in comparison with non DHT alloys. The formation of diffusion layer in DHT alloy caused a mismatch of deformation modes between the surface layer and the interior.
It was observed using HR-TEM that the growth of ω particles were remarkably retarded in the interior of aged DHT alloy, and the center of the ω particle was reversely transformed to β phase. It was also found that an unusual fcc phase was formed by the stress induced stacking faults at the interface.View full abstractDownload PDF (2365K) -
Hideaki Miyagawa, Hideharu Nakashima, Hideo Yoshinaga1992 Volume 56 Issue 5 Pages 531-540
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFor examining the general applicability of the prediction method proposed in our previous paper (1991) for the flow behavior of solution hardened alloys, experimental stress-strain and creep curves obtained for Al-Mg alloys with various solute concentrations (3.0∼6.9 at%Mg) at various temperatures (573∼723 K) were used.
It is suggested that all of the four parameters used for the prediction should be almost independent of solute concentration, and among them the three parameters concerning recovery and dislocation multiplication should depend on temperature. The stress-strain curves and creep curves predicted by considering the temperature dependence can well reproduce all of the experimental curves used, so long as the solute atmosphere drag mechanism should operate.View full abstractDownload PDF (1320K) -
Shinji Hirai, Masayoshi Ozawa, Hiroshi G. Katayama, Yoichiro Uemura1992 Volume 56 Issue 5 Pages 541-547
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to elucidate the formation process of AlN and ALON layers, reduction experiments were conducted using carbon-deposited sapphire substrates. The results are as follows: (1) In the initial stage of reducing and nitriding of the A-plane sapphire substrate, the c-axis of the AlN crystal grew vertically to the face of the substrate, resulting in the relation of AlN(001)\varparallelAl2O3(110). In the case of C-plane, an AlN crystal plane indicating an inclined c-axis was initially obtained, and then the polycrystallization of AlN occured in the later stage of reaction. In the case of R-plane, polycrystallization was observed from the initial stage of reaction. (2) Reduction and nitriding were facilitated in the order of A-plane<C-plane<R-plane with the corresponding thickness of the AlN layer. (3) Pores were observed on the surface and underlying sections of the AlN layers. The pores grew larger in size and more abundant in the order of A-plane<C-plane<R-plane, corresponding to the order of progress in reaction. (4) Interdiffusion of CO, N2 and CO2 through the pores within the AlN layer formed on the sapphire substrate may be the main rate-determing process. However, above 1973 K the resistance of interdiffusion of O2− and N−3 within the ALON layer was presumed to increase relatively, because the ALON layer was formed in the interface of the AlN layer and sapphire, and it contain few pores.View full abstractDownload PDF (1820K) -
Shuichi Yamazaki1992 Volume 56 Issue 5 Pages 548-552
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSInterpretation of infrared reflection-absorption spectra for inorganic films on metallic substrates is complicated by distorted band shapes and frequency shifts as compared to the absorption spectra of bulk material. These alterations were successfully estimated by a theoretical expression for reflection spectra with the optical constants which were derived from the transmission spectra of bulk materials by the KBr pellet technique and Kramers-Kronig analysis. Some regularity was found between transmission spectra of oxides and reflection-absorption spectra of inorganic films on metals, and it was interpreted by the behavior of dispersion in the real part of refractive index and the theoretical expression of reflection spectra.View full abstractDownload PDF (688K) -
Yuichi Sato, Tsutomu Ozawa, Takashi Sato1992 Volume 56 Issue 5 Pages 553-557
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSRibbon formation in the single roller process was investigated to establish the casting process for ultra-wide ribbon. Observations of castings by photographs indicated that a melt puddle was formed between the nozzle and the wheel surface, and a ribbon was produced on the wheel surface. The thickness of the ribbon obtained was about 50 μm and this value was much smaller than the height of the melt puddle. Furthermore, the effect of the height and the length in the casting direction of the melt puddle on ribbon thickness was examined. The ribbon thickness was dependent on the length of the melt puddle in the casting direction, i.e., as the length of the melt puddle increased, the ribbon thickness increased. On the other hand, the ribbon thickness was independent of the height of the melt puddle. From the results of the present examinations, it is important to make the length of the melt puddle in the casting direction uniform across the width of the ribbon in order to obtain ultra-wide ribbon with uniform thickness.View full abstractDownload PDF (769K) -
Shozo Inoue, Hitoshi Uchida, Yoichi Tokunaga, Keiji Koterazawa1992 Volume 56 Issue 5 Pages 558-564
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIII-V compound of AlN with good thermal and chemical stability shows good thermal conductivity and high electrical resistivity. Thus AlN films can be a useful material in electrical and optical applications. The purpose of this work is to study the dependence of deposition conditions on the crystallographic structure and the composition of rf reactive sputtered AlNx films.
AlNx films were deposited onto slide glasses at room temperature by rf sputtering of pure Al disk (70 mm in diameter) with Ar+N2 mixed gas. The total gas pressure was kept at 0.4 Pa through out this work. The N2 partial pressure-to-total pressure ratio in the sputtering gas, PN2⁄Ptotal, was changed from 0.0 to 1.0. The structure and the composition of films were characterized by X-ray diffractometry and Auger electron spectroscopy, respectively.
The deposition rate decreased gradually with increasing PN2⁄Ptotal, and decreased drastically when PN2⁄Ptotal increased above a threshold value. This threshold value of PN2⁄Ptotal was about 0.5 at rf power of 300 W, and decreased with decreasing the applied rf power. It is shown that the films prepared at above the threshold value were transparent and have an AlN single phase. The film prepared nearly at the threshold value has a highly distorted AlN structure. Quadrupde mass analysis of exhaust gas showed that N2 molecules scarecely existed below the threshold value. The spectroscopic measurement of glow discharge plasma during sputtering suggested that N+2 species might have an important role in the deposition of AlN single phase films.View full abstractDownload PDF (885K) -
Hidenori Kohzuki, Muneyuki Motoyama1992 Volume 56 Issue 5 Pages 565-571
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBK X-ray spectra were measured precisely from some boron nitride(BN) powders of different crystal structures by an electron probe microanalyzer(EPMA), in order to investigate the change in spectral features with the crystal structures. BK X-ray spectra of several BN films deposited by an ion plating method were measured by an EPMA. Their spectral features were discussed in comparison with those of BN powders.
It was observed that the position of BK main peaks of BN powders shifted from that of metallic B to the long wavelength side, and that these spectra accompanied a satellite peak at the long wavelength side of the main peak and two satellite peaks at the short wavelength side of the main peak. It was found that the BK X-ray spectra of BN powders changed with their crystal structures in the spectral features such as the position and the asymmetric index of the main peak or the position and the relative intensity of the satellite peak. Accordingly, the crystal structure of BN powder could be identified by BK X-ray spectral feature.
BK X-ray spectra were measured by an EPMA for the BN films having the thickness of about 200 nm and the grain size of about 10 nm. The BK X-ray spectra of the BN films, which had been identified as cubic boron nitride(cBN) by infrared absorption spectra and electron diffraction patterns, were different from that of cBN powder in the spectral features such as the position and the asymmetric index of the main peak or the position and the relative intensity of satellite peak. Therefore, it was presumed that there was some difference in the crystal structure between cBN thin film and cBN powder.View full abstractDownload PDF (949K) -
Hidenori Kohzuki, Muneyuki Motoyama1992 Volume 56 Issue 5 Pages 572-578
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe authors have reported that the crystal structure of boron nitride (BN) was reflected in the spectral feature of its BK X-ray emission spectrum. BN films were deposited on Si wafer in N2 or N2+Ar atmosphere by varying the r.f. power applied to a substrate, using the reactive ion plating method with a hot cathod plasma discharge within parallel magnetic field. Those structures were investigated by BK X-ray emission spectra measured with an EPMA and infrared (IR) absorption spectra.
The BN films deposited in N2 atmosphere at the r.f. power less than 200 W were considered to be composed of elemental boron and BN having 3-coordinated structure which was a similar crystal structure of rhombohedral BN(rBN) or turbostratic BN(tBN). The amorphous BN was formed in the films at r.f. power more than 200 W. Therefore, the r.f. power must be less than 200 W for depositing crystalline BN films.
The BN films deposited in N2+Ar atmosphere at the r.f. power less than 200 W had three IR absorption peaks at 1380, 1050 and 800 cm−1. It was considered from the spectral feature of BK X-ray emission spectra that the BN having a IR absorption peak at 1050 cm−1 was 4-coordinated structure which was a similar crystal structure of wurtzite-type BN, and that the BN having IR absorption peaks at 1380 and 800 cm−1 was 3-coordinated structure which was a similar crystal structure of rBN or tBN. These BN films were composed of both BNs.
The contents of each BN in the films mixed 3- and 4-coordinated structures could be estimated by the main peak positions of BK X-ray emission spectra obtained from the BN films.View full abstractDownload PDF (958K) -
Osamu Ohashi, Seiichiro Suga1992 Volume 56 Issue 5 Pages 579-585
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo clarify the relationship between surface composition before contact and bond formation in diffusion-welding of SUS304 stainless steel, Auger analyses of surface composition were carried out at elevated temperature using the Auger spectroscopy instrument with the heating device. Joints were made with ultra high vacuum diffusion welding equipment.
Bond formation at the contact area depends on the disappearance of the surface film which consists of oxygen and carbon. The film disappears above 800°C, and sulfur in steel segregates to the surface. The thickness of the sulfur-rich layer (above 20 at%) is 0.3-2 nm. SUS304 stainless steel is covered with sulfur-rich layer and can be joined above 650°C, since the sulfur diffuses from the contact surface to base metal. When the specimens are pre-heated above 800°C in a vacuum, the bonding of the specimens can be attained at a lower temperature than a conventional joining process.View full abstractDownload PDF (1213K) -
Momoki Kamo, Sang-Soo Oh, Kozo Osamura1992 Volume 56 Issue 5 Pages 586-591
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe microstructure change and its influence on superconducting properties have been investigated for the Ag sheathed Bi2223 tapes prepared by adding Sn, Ba and Mg elements to the Bi-Pb-Sr-Ca-Cu-O system. The superconducting properties were apparently improved by the Ba or Mg addition. This may be attributed to the dense and textured structure produced by the Ba addition or the fine dispersion of MgO particles produced by the Mg addition. On the other hand, the superconducting property of Sn added tapes was found to be inferior to that of none added tape, because the volume fraction of 2223 phase decreased by the Sn addition.View full abstractDownload PDF (1199K) -
Shozaburo Nakashima, Kunihide Takashima, Jiro Harase1992 Volume 56 Issue 5 Pages 592-599
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study was made on the effect of Sn addition to 3 mass%Si steel containing MnS or AlN on the dispersion of precipitates and the grain growth of recrystallized grains. Following conclusions were obtained.
1. Specimen with MnS
(1) Sn addition promotes largely the precipitation of MnS in the courses of hot-rolling, annealing of hot-band and decarburizing annealing after cold-rolling, and as the results, enlarges the Zener factor after decarburizing annealing.
(2) By Sn addition, the average size of recrystallized grains decreases after decarburizing annealing. Some grains in the Sn added specimen become remarkably large in the heating stage of final annealing.
2. Specimen with AlN
(1) Sn addition changes the dispersion of AlN little.
(2) The change by Sn addition in the size of recrystallized grains in the specimen with AlN is similar to that in the specimen with MnS. Generally, the average grain size in the specimen with AlN is larger after decarburizing annealing and smaller in the heating stage of final annealing than that in the specimen with MnS.
3. Main effect of inhibitors and Sn addition on the growth of recrystallized grains
It is considered that MnS decreases the size of primarily recrystallized grains after decarburizing annealing, and that AlN restrains matrix-grains from growing until the high temperatures in the heating stage of final annealing and gives specially oriented grains an advantageous condition to grow. Sn has an effect on promoting the growth of specially oriented grains.View full abstractDownload PDF (2839K) -
Hideaki Ono, Masashi Fujinaga, Takaharu Yonemoto, Tsugio Miyagawa1992 Volume 56 Issue 5 Pages 600-603
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFe/Fe-N multilyered films have been prepared by alternation of RF magnetron sputtering deposition and ECR plasma nitridation, and their soft magnetic properties and structures have been investigated. On the most suitable preparing conditions, they indicate high saturastion flux density Bs=1.81∼1.86 T, low coercivity Hc=25∼30 A/m and high permeability μ′=2300 at 20 MHz. In Fe/Fe-N films, periodic structure of concentration can be observed for Fe and N, and N atoms are intruded into Fe about 10 mol%. This unequilibrium α-Fe-N solid solution is transformed to γ′-Fe4N after annealing in vacuum. Factors of good soft magnetic properties are considered as follows.
(1) The magnetic elastic effect of α-Fe stretched by N atoms.
(2) Reduced effective magnetic anisotoropy as fine crystal grains.View full abstractDownload PDF (791K) -
Hiroshi Fujimura, Katsuro Oda, Nobusato Kojima, Hiromitsu Ino1992 Volume 56 Issue 5 Pages 604-605
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (301K) -
Hiroki Esaki, Kei Ameyama, Masaharu Tokizane1992 Volume 56 Issue 5 Pages 606-607
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (592K)
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