All issues
Volume 54, Issue 11
November
Displaying 1-12 of 12 articles from this issue
- |<
- <
- 1
- >
- >|
Paper
Paper
-
Koji Fukushima, Masafumi Kobune, Yusuke Nishioka, Toru Yamaji, Tetsuo ...Article type: Paper
2007 Volume 54 Issue 11 Pages 735-739
Published: 2007
Released on J-STAGE: July 11, 2008
JOURNAL OPEN ACCESSCrystalline Pb(Zr0.3Ti0.7)O3 films with (001), (101) and (111) orientations were successfully fabricated on PbTiO3(PT)/Pt(111)/SiO2/Si(100) substrates, crystallized from an amorphous state by hot isostatic pressing (HIP). The crystallized PZT films had a preferential (001) orientation, with the degree of c-axis orientation α in the range of 0.49 to 0.61. From measurements of fatigue and imprint characteristics, PZT films HIP-treated at 1.5 MPa using a three-step (500-600-700°C) annealing program were shown to have the ability to be used as high-endurance and high-density element materials for ferroelectric random access memory (FeRAM) applications.View full abstractDownload PDF (1659K)
Rapid Communication
-
Yuri Hashida, Hidetaka Hayashi, Akira KishimotoArticle type: Rapid Communication
2007 Volume 54 Issue 11 Pages 740-743
Published: 2007
Released on J-STAGE: July 11, 2008
JOURNAL OPEN ACCESSModel ceramic foams were fabricated by expanding once-sintered dense shells utilizing the superplastic deformation of 8 mol% yttria-stabilized zirconia (8YSZ) dispersed with silica, titania or alumina. Similar to the case without dispersoid, 8YSZ based ceramic foam could not be fabricated with any amount of alumina addition. By adding silica more than 20 mol%, ceramic mono-foam can successfully be fabricated. The porosity increased with the sintering time up to 24h, then saturated at about 40%. The porosity also increased with the amount of silica addition. In the case of titania addition, porosity was smaller compared with the same amount of silica addition.View full abstractDownload PDF (752K)
Special Issue:Fundamentals and Applications of Bulk Metallic Glasses and Nano-crystalline Alloys
Summarization
-
Akihisa InoueArticle type: Summarization
2007 Volume 54 Issue 11 Pages 746
Published: 2007
Released on J-STAGE: July 11, 2008
JOURNAL OPEN ACCESSDownload PDF (162K)
Review
-
Yoshihiko Hirotsu, Akihiko HirataArticle type: Review
2007 Volume 54 Issue 11 Pages 747-753
Published: 2007
Released on J-STAGE: July 11, 2008
JOURNAL OPEN ACCESSLocal atomic structures of Pd- and Fe-based metallic glasses (Pd40Ni40P20 and Fe84Nb7B9) were investigated by means of transmission electron microscopy (TEM). In these typical metallic glasses, local structures of nanoscale phase separation were observed using high-resolution TEM and nanobeam electron diffraction. A structural modeling of the Pd-based metallic glass with the observed local structures was also performed with the help of computer simulation which explained an energy-filtered electron diffraction data. The obtained results show that the comprehensive TEM study is useful to understand nanoscale structural organizations in metallic glasses.View full abstractDownload PDF (1345K)
Paper
-
Daisuke Fukamaki, Tsunehiro Takeuchi, Kazuo Soda, Masashi Hasegawa, Ui ...Article type: Paper
2007 Volume 54 Issue 11 Pages 754-760
Published: 2007
Released on J-STAGE: July 11, 2008
JOURNAL OPEN ACCESSStability of the Pd40Ni40P20 bulk metallic glass (BMG) was investigated by making full use of its relevant crystals which possess the same local atomic arrangements (trigonal prism cluster) about phosphorus as those in the BMG. The electronic structure of relevant crystals calculated by the FLAPW band calculation showed covalent bonds between phosphorus and transition metal elements (nickel and palladium). This covalent bonds must lead to a low internal energy of the relevant crystals, and perhaps of the corresponding metallic glass. Characteristics in the density of states were well reproduced in the cluster orbitals of the (Pd, Ni)9P trigonal cluster calculated by the DV-Xα method. This fact indicates that the electronic structure of the relevant crystals is dominated by that of the trigonal cluster. Photoemission spectroscopy on the relevant crystals and the BMG proved that all these phases possess nearly the same electronic structure. It is concluded that the structure of BMG is built up with the random network of the (Pd, Ni)9P clusters with large degree of flexibility with keeping the low internal energy. This condition must lead to a decrease of free energy of the system and stabilize the BMG.View full abstractDownload PDF (1498K)
Review
-
Ryuzo Watanabe, Hisamichi Kimura, Hidemi Kato, Akihisa InoueArticle type: Review
2007 Volume 54 Issue 11 Pages 761-767
Published: 2007
Released on J-STAGE: July 11, 2008
JOURNAL OPEN ACCESSHot pressing mechanisms are reviewed with special interest in the hot consolidation of metallic glass powders that exhibit a perfect viscous flow above the glass transition temperatures. The total densification process is divided into three stages; neck growth stage, cylindrical pore stage and isolated pore stage, for each of which the densification model and the critical relative density, separating the three stages, are unequivocally represented. The kinetic equations for the densification during hot pressing by the viscous flow mechanism are derived from those hitherto proposed for the power-law creep mechanism, in which the index of the constitutive equation is set to be unity. The equations for the relative density as functions of the hot pressing time and pressure are provided for the three stages of densification. An application of the kinetic equations to a processing design of the hot consolidation of metallic glass powders is demonstrated. The proposed set of the three equations enables an estimation of appropriate pressure and time for the full consolidation of metallic glass powders. The influence of entrapped gas in the final stage of hot pressing is also discussed.View full abstractDownload PDF (752K)
Paper
-
Takao Mizushima, Hisato Koshiba, Yutaka Naito, Akihisa InoueArticle type: Paper
2007 Volume 54 Issue 11 Pages 768-772
Published: 2007
Released on J-STAGE: July 11, 2008
JOURNAL OPEN ACCESSNew core (LiqualloyTM core) made of soft magnetic Fe-based glassy alloy powder was fabricated by the consolidation using an uni-axial mechanical press at room temperature. This new core has the constant relative permeability (μ') of about 60 up to 1 MHz and extremely low core loss blow 200kW/m3 at f=100kHz and Bm=0.1 T. The efficiency of the switching power supply (η) was improved by 2∼3% when the LiqualloyTM core was used instead of Fe-Al-Si core. The temperature rise near the LiqualloyTM core (ΔT) was also 10K lower than that of the Fe-Al-Si core. These excellent properties of the LiqualloyTM core are based on its extremely low hysteresis and eddy current losses. These low losses are originated from its good soft magnetic properties (Hc=2A/m) after annealing at relatively low temperature, its intrinsic hardness (Hv=1000) and high resistivitiy (ρ=160μΩcm).View full abstractDownload PDF (622K) -
Masanori Yokoyama, Shin-ichi Yamaura, Hisamichi Kimura, Akihisa InoueArticle type: Paper
2007 Volume 54 Issue 11 Pages 773-777
Published: 2007
Released on J-STAGE: July 11, 2008
JOURNAL OPEN ACCESSOptimum alloy compositions of the Ni-Nb-Cr-Mo-P-B, Ni-Cr-Nb-P-B and Ni-Cr-Mo-P-B glassy alloys were investigated for trail production of separator of fuel cell. Eventually the Ni60Nb2Cr16Mo2P16B4, Ni65Cr10Nb5P16B4 and Ni65Cr10Mo5P16B4 glassy alloys were chosen from the viewpoint of having a wide supercooled liquid region.
Then the groove formability of the compositionally optimized alloys in a supercooled liquid state was studied by hot-pressing with the dies having precise grooves. A precise groove forming can be achieved by hot-pressing the Ni60Nb2Cr16Mo2P16B4 and Ni65Cr10Mo5P16B4 glassy alloys in a supercooled liquid state at Tg + 20 K. However, it was difficult to form the precise grooves in the Ni65Cr10Nb5P16B4 glassy alloy.
Finally, we successfully demonstrated that it is possible to form the grooves by hot-pressing using viscous flow deformation in a supercooled liquid state and to produce metallic glassy separators for proton exchange membrane fuel cells (PEMFC).View full abstractDownload PDF (803K)
Rapid Communication
-
Kiyoshi Okumura, Koji Kajita, Junkou Kurosaki, Hisamichi Kimura, Akihi ...Article type: Rapid Communicatin
2007 Volume 54 Issue 11 Pages 778-783
Published: 2007
Released on J-STAGE: July 11, 2008
JOURNAL OPEN ACCESSApplication of bulk metallic glasses was examined as the shot for the peening, which, as a reforming technology of the material, much attention is paid to in these days. As the strength of target products of peening is becoming higher, the shot is also demanded to be made of high hardness. The conventional shot has low toughness and is easy to be crushed. It has led to problems of increase in cost and waste. Therefore, we have tried to solve these problems by applying the bulk metallic glasses as shot. We have paid attention to Fe-base metallic glass system, and have searched for and found the best composition with high hardness and high toughness. Spheroidal particles made with the Fe-base metallic glass were used as shot for peening, and it was proved that this is of high hardness together with a long-life. Thus, we could develop new shot material for peening. We report details of development, and the characteristic when Fe-base metallic glass is applied to the shot for peening.View full abstractDownload PDF (1326K)
Paper
-
Masaharu Sugiyama, Takanori Igarashi, Masahiro Fukumoto, Hisamichi Kim ...Article type: Paper
2007 Volume 54 Issue 11 Pages 784-789
Published: 2007
Released on J-STAGE: July 11, 2008
JOURNAL OPEN ACCESSSome of the bulk metallic glass have high strength and high corrosion resistance. We have created a thermal spray coating of Fe-based metallic glass by High Velocity Oxy-Fuel process on various substrates such as stainless steel, aluminum alloy and magnesium alloy. We have examined the structure of coatings and we have found that the coatings are single glassy layer, they has very few porosities and also it is dense. Hardness of the coating is from Hv1000 to 1100. That is harder than hard chrome plating. The anodic polarization curve of the coating has stable density of current throughout a broad band of potential. This density of current is less than 0.1% of SUS304 stainless plate. The coating on the substrate of stainless steel shows a high erosion resistance against lead-free solder with Sn-3mass% Ag-0.5mass%Cu. We have applied this coating for a solder fusing vessel of stainless steel sheet on a continuous casting machine for this lead-free solder. This machine is in operation for two years, and now no erosions nor damages have yet occurred.View full abstractDownload PDF (1184K) -
Hyunguen Kim, Yoshitsugu Motoe, Koji Nakashima, Takanori Igarashi, Kaz ...Article type: Paper
2007 Volume 54 Issue 11 Pages 790-794
Published: 2007
Released on J-STAGE: July 11, 2008
JOURNAL OPEN ACCESSFormation of Fe43Cr16Mo16C14B10 metallic glass phase on the aluminum alloy substrate has bean a high velocity oxy-fuel (HVOF). Fe-based metallic glass sprayed coating with the thickness of about 200∼250μm has been successfully formed on the A5052 aluminum alloy substrate with good adhesion by HVOF spraying process. Sprayed coating with the amorphous state exhibited high hardness with Vickers Micro hardness of HV 913-1120 and low wears loss, but comparably high friction coefficient of 0.7 to 0.8 evaluated by a ball-on-disc wear test under dry condition. However, friction coefficient of the Fe-based metallic glass sprayed coating can be improved to 0.07μ by using engine oil as a lubricant.View full abstractDownload PDF (946K) -
Katsuhiko Asami, Hisamichi Kimura, Akihisa InoueArticle type: Paper
2007 Volume 54 Issue 11 Pages 795-800
Published: 2007
Released on J-STAGE: July 11, 2008
JOURNAL OPEN ACCESSSome of amorphous alloys have very high corrosion resistance. However, there are few studies on corrosion phenomena of metallic glasses. The corrosion resistance of alloys is generally related with composition and structure of surface films of the alloys. Therefore, not only investigation of corrosion resistance, but also study on surface film characterization is important. In this paper, corrosion resistance of Zr-, Ni-, Fe- and Cu-based bulk bulk metallic glasses was reviewed. A general trend of preparation of corrosion resistant bulk metallic glasses was made clear. It was found that addition of such an element as Nb, Ta, Ti, Cr, Mo and P was effective for the corrosion resistance. It was also clarified that the effectiveness depended on alloy systems and environments. Co-addition of Ni and Nb was effective in preventing from decrease of glass forming ability together with increase in corrosion resistance. However, when the amount of addition of these elements exceeded a certain level, the glass forming ability of the alloy decreased, and accordingly it led deterioration in corrosion resitance of the alloy.View full abstractDownload PDF (801K)
- |<
- <
- 1
- >
- >|