巻号一覧
48 巻, 4 号
選択された号の論文の13件中1～13を表示しています
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黒木 英憲2001 年 48 巻 4 号 p. 293-304
発行日: 2001/04/15
公開日: 2009/05/22
ジャーナル フリーB addition, including simultaneous addition of B and C, in plain Fe, low alloy steels and stainless steels is effective to promote sintering. A small amount of added B forms steepened liquidus of Fe-B, Fe-B-C or other eutectic reactions in phase diagrams of those alloy systems. Following the formation of the eutectic liquids in the alloys, rapid densification and spherodization of pores proceed leading to the improvements of mechanical properties.
In plain Fe and Fe-C steels, B is detected only in the particle boundary area; forming eutectic boride or borocarbide. B addition to a eutectoid Fe-C steel forms a ferritic surface layer on particles together with boundary borocarbide network, while in Cr and/or Mo containing steels, B exists both in the boundary area and within the matrix particles; forming (Fe, Cr, Mo)2B precipitates in the matrix.
B will react with N in commercial sintering atmospheres forming hexagonal BN, which may become the site for the epitaxial precipitation of secondary graphite from the matrix containing C.抄録全体を表示PDF形式でダウンロード (8239K) -
上ノ薗 聡, 尾崎 由紀子, 杉原 裕2001 年 48 巻 4 号 p. 305-310
発行日: 2001/04/15
公開日: 2010/07/12
ジャーナル フリーAdhesive forces of the segregation-free iron based powder mixes, which consist of liquid bridge force, electrostatic force and van der Waals force were calculated and the absorption isotherm of water vapor on the segregation-free iron based powder mixes, were measured. The result indicated that the van der Waals force between binder on iron particles and lubricant particles and that between lubricant particles were main forces that determine the flowability of segregation-free iron based powder mix in the relative humidity atmosphere less than 91%.
A new high flowable segregation-free iron-based powder mix with wax lubricant, CLEAN MIX (KWAX-B) has been developed by means of developing a new lubricant system to decrease the van der Waals forces related to lubricant powders.
It showed a better flowability than that of a conventional one. Furthermore lubricant was hardly adhered to inner parts of screw conveyer during transportation.
The powder characteristics, such as compressibility, rattler value and ejection force of CLEAN MIX (KWAX-B), and the mechanical properties, such as tensile strength, Charpy impact value and dimensional change during sinering the compacct were almost the equal to those of the conventional segregation-free iron based powder mix with wax lubricant.抄録全体を表示PDF形式でダウンロード (2172K) -
橋井 光弥, 徳満 和人2001 年 48 巻 4 号 p. 311-315
発行日: 2001/04/15
公開日: 2009/05/22
ジャーナル フリーThe structural change for mechanically alloyed Fe50Al50 powder in annealing process was studied by vibrating sample magnetometer (VSM) and 57Fe Mossbauer spectroscopy method. The ferromagnetic components became extinct after mechanical alloying. The spectrum was fitted with 2 doublets on the mechanically alloyed powders. The integrated intensity of one doublet increased with annealing time while that of the other doublet decreased. It is considered that mechanically alloyed Fe50Al50 powder is constituted of two kinds of phases with different atomic configurations, which correspond to the ordered and the disordered structures. The ratio of the ordered FeAl phase and the disordered FeAI phase would be 4:6 in the mechanically alloyed powder. And first component increased by annealing at 673 K.抄録全体を表示PDF形式でダウンロード (374K) -
徐 元斌, 野村 宏之, 滝田 光晴, 戸田 浩之2001 年 48 巻 4 号 p. 316-321
発行日: 2001/04/15
公開日: 2009/12/04
ジャーナル フリーThe application of MIM (Metal Injection Molding) process for implant material Ti-5A1-2.5Fe alloy has been investigated using blended metal powder. The emphasis is laid upon studying influence of the experimental parameters on the process of alloy element homogenization. Under the sintering condition of 1323 K × 24 h or 1373 K × 10 h, the composition is sufficiently homogenized and a sintered compact with relative density higher than 95% is obtained. The microstructure of the corresponding compacts mainly consist of bunches of parallel aligned needle-like α phase. The tensile strength of the compacts reaches 970 MPa which is higher than that of cast alloy of the same composition, but the elongation is lower than that of the cast alloy. It is speculated that the above phenomena originated from the more excess oxygen content in the compact than that of the cast alloy.抄録全体を表示PDF形式でダウンロード (5611K) -
松田 健次, 今里 州一, 徳本 啓, 兼田 〓宏2001 年 48 巻 4 号 p. 322-327
発行日: 2001/04/15
公開日: 2009/05/22
ジャーナル フリーA possible mechanism for the occurrence of numerous shallow cracks, which were observed on the rubbing surface of cemented carbide, was studied The experiments were conducted using an apparatus simulated mechanical face seal composed of two kinds of ceramics rings and cemented carbide ring, with distilled water as the liquid to be sealed. The variations of rubbing surfaces of cemented carbide were examined in detail by using the Vickers indentations. Although the crack spacing gradually decreased with increasing the number of cracks, new crack was hardly formed between the precracks if the crack spacing fell below a critical value. If the Vickers indentation tests were conducted on the rubbing surface where the crack spacing was larger than the critical value, indentation cracks with almost the same length as the neighboring precracks could be formed. It was also found that the surface near the crack piled up in both cases where the crack was caused by rubbing test and by the Vickers indentation test. These results suggested that the cracking occurred by the tensile residual surface stress. A method to predict the magnitude of the tensile residual stress by measuring the surface profile was also proposed.抄録全体を表示PDF形式でダウンロード (5611K) -
土肥 義治, 松木 賢司, 秋元 仁, 會田 哲夫, 落合 鍾一2001 年 48 巻 4 号 p. 328-334
発行日: 2001/04/15
公開日: 2009/12/04
ジャーナル フリーGrain refinement of Ni3AI (γ') and NiA1(β) two-phase nickel aluminides (34A1), together with nominally single γ' phase (30A1) or β phase (43A1) nickel aluminides has been attained by a wet mechanical alloying and vacuum hot pressing process. The average grain sizes of the three as-compacted intermetallics were very close and about 1.0 μm. High temperature compression tests were carried out at a temperature range of 1073 K-1273 K and at an initial strain rate range of 1.4×10-4s-1- 5.6×10-2 s-1. Tensile tests were also performed at selected strain rates at 1273 K.
The strain rate sensitivity exponent m for 34A1 evaluated by compression test at 1273 K was as high as 0.38 at an initial strain rate range from 1.4×10-4s-1 to 5.6×10-2 s-1. The maximum elongation of about 250% was obtained at a strain rate of 4.2×10-3s-1 for 34A1. Even at high strain rate of 4.2×10-2s-1 and at 1273 K, 188% elongation was obtained for 34A1. These results suggested the possibility of high strain rate superplasticity in the two phase intermetallics. By the microstructure observations using SEM and TEM, grain boundary sliding and dislocation activity within grains were found in the two phase intermetallics deformed at the strain rates higher than 10-2s-1. The deformation behavior and mechanism for the two phase nickel aluminides were discussed in the comparison of the results of γ' and β nominally single phase intermetallics.抄録全体を表示PDF形式でダウンロード (5761K) -
Yoshikazu Suzuki, Naoki Kondo, Tatsuki Ohji2001 年 48 巻 4 号 p. 335-340
発行日: 2001/04/15
公開日: 2009/05/22
ジャーナル フリーMicrostructure and pore-size distribution of the porous CaZrO3/MgO in situ composites were modified by the addition of SiC. A porous composite with bimodal pore-size distribution (peaks at -1 μm and-17μm, porosity Vp=59%) was obtained by the pressureless reactive sintering of CaMg(CO3)2 (dolomite), ZrO2 and SiC mixtures with a small amount of LiF in air. In an oxidative sintering atmosphere, SiC presumably acted as a "precursor" of SiO2 at elevated temperatures, and contributed to the "partial" liquid phase sintering in the powder compact.抄録全体を表示PDF形式でダウンロード (4332K) -
Hideki Kume, Yoshito Nishikawa, Díaz De la Torre Sebastiá ...2001 年 48 巻 4 号 p. 341-344
発行日: 2001/04/15
公開日: 2009/05/22
ジャーナル フリーA12O3-5mass%Y3Al5O12 (YAG) composites were fabricated by the coprecipitation method. The bending strength of sintered bodies was estimated. The YAG particles were homogeneously dispersed into the Al2O3 grains hindering the matrix grain growth. The bending strength of the composites was enhanced as compared to alumina monolithic materials. Both the processing and mechanical properties of the developed composites are discussed.抄録全体を表示PDF形式でダウンロード (2135K) -
関野 徹2001 年 48 巻 4 号 p. 346
発行日: 2001/04/15
公開日: 2009/05/22
ジャーナル フリーPDF形式でダウンロード (111K) -
大司 達樹2001 年 48 巻 4 号 p. 347-352
発行日: 2001/04/15
公開日: 2009/05/22
ジャーナル フリーThe dispersion of nanometer-sized silicon carbide particles into alumina or silicon nitride matrix results in significant improvements both in the fracture strength and the creep resistance. In this study the strengthening mechanisms of these two properties are analyzed and discussed. For the fracture strength, crack-tip bridging by nano-particles is considered to be one of the primary mechanisms. Small brittle particulate inclusions have been shown to cause crack-tip bridging at short distances behind the crack tip. This mechanism leads to modest toughness but very steep R-curve. For the creep resistance, much attention is paid to the interfaces between the intergranular nanoparticles and the matrix, and its role in creep inhibition. The intergranular nanoparticles are rigidly bonded to the matrix, which causes the inhibition of grain boundary sliding, leading the remarkably improved creep resistance. It is also demonstrated that the creep rates are remarkably decayed below specific stresses, suggesting the presences of the threshold stresses of creep. These stresses agree with those predicted from the Ashby's model, where motion of grain boundary dislocations responsible for vacancy nucleation and annihilation is considered to be pinned by hard particles.抄録全体を表示PDF形式でダウンロード (3732K) -
奥山 秀男, 本間 一廣, 大野 悟, 目 義雄2001 年 48 巻 4 号 p. 353-357
発行日: 2001/04/15
公開日: 2009/05/22
ジャーナル フリーFabrication of palladium layer having flexible shape and strength was attempted by using ultrafine particles. Continuous process of the preparation of palladium ultrafine particle and their deposition on a filter substrate of stainless steel fiber has been demonstrated. The layer was separated from the filter and/or cracked during the heating due to the following reason; (1) low density of the deposited layer, (2) density distribution along the depth direction of the layer, and (3) stress between the layer and the filter coming from the shrinkage of layer and expansion of filter. To solve the above problem, the layer was compressed and heated under pressure. Uniform and well-contacted layer on the stainless steel filter was successfully prepared.抄録全体を表示PDF形式でダウンロード (4642K) -
江崎 剛, 石原 慶一, 新宮 秀夫2001 年 48 巻 4 号 p. 358-362
発行日: 2001/04/15
公開日: 2009/05/22
ジャーナル フリーMultilayerd Fe-Ag laminates were prepared by the repeated pressing-rolling and hot-sheath-rolling process. As starting materials, Fe sheets (30 or 60μm) and Ag sheets (30μm) were alternatively stacked. In this work, the metallographic structure and the mechanical properties were investigated. The strength of samples was evaluated by extension tests. As the layer thickness reduced, the yield stress became higher due to the grain size reduction and work hardening. The yield stress obeyed the Hall-Petch equation. The maximum yield stress was 850 MPa with 65 nm bilayer thickness, and in the sample of smaller layer thickness than that, strength slightly decreased. Anisotropy of strength was generated by rolling texture and recrystallization texture in the laminates. Strength and ductility varied with Fe and Ag volume ratios following the rule of mixture.抄録全体を表示PDF形式でダウンロード (5370K) -
酒井 永典, 石原 慶一, 新宮 秀夫2001 年 48 巻 4 号 p. 363-367
発行日: 2001/04/15
公開日: 2009/05/22
ジャーナル フリーRepeated pressing and rolling process was applied for both alternatively stacked elemental foils and elemental powder mixtures of the Ag-Fe system. In both cases, the nano-scaled multilayer was obtained. In this work, the thermoelectricity, magnetoresistance (MR) and specific resistance were investigated. Thermoelectric power decreased when layer thickness became thinner. The decreasing value on the direction parallel to layers (RD: Rolling Direction) is larger than that on the direction perpendicular to layers (ND: Normal Direction). Thermoelectric power of the thinnest sample of both directions shows negative value though those of Fe and Ag are positive. The change of thermoelectricity correlates with that of MR, and the both phenomena are affected by the electron scattering at layer boundaries. RD-thermoelectric power and RD-specific resistance of multilayer were proportional to the inverse of layer thickness.抄録全体を表示PDF形式でダウンロード (1989K)
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