巻号一覧
62 巻, 11 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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解説
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辻 伸泰原稿種別: 解説
2012 年 62 巻 11 号 p. 392-397
発行日: 2012/11/30
公開日: 2013/02/28
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堀田 善治, 廣澤 渉一, 松田 健二, 寺田 大将原稿種別: 解説
2012 年 62 巻 11 号 p. 398-405
発行日: 2012/11/30
公開日: 2013/02/28
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倉本 繁, 古田 忠彦, 長廻 尚之原稿種別: 解説
2012 年 62 巻 11 号 p. 406-411
発行日: 2012/11/30
公開日: 2013/02/28
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中野 博昭, 孫 仁俊原稿種別: 解説
2012 年 62 巻 11 号 p. 412-418
発行日: 2012/11/30
公開日: 2013/02/28
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研究論文
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久保田 正広原稿種別: 研究論文
2012 年 62 巻 11 号 p. 419-423
発行日: 2012/11/30
公開日: 2012/12/30
ジャーナル フリーPure aluminum powders were mechanically milled (MM) using a vibration type of ball mill. Changes in hardness and solid-state reactions of the MMed pure aluminum powders have been examined by microhardness measurements and X-ray diffraction (XRD). Microstructure of the MMed pure aluminum powders was characterized by transmission electron microscopy (TEM). The Vickers microhardness of the pure aluminum powders increased from 44 to 138 HV after MM time from 0 to 4 h, respectively, and exhibited a broad hardness plateau at maximum hardness after MM time to 64 h. Characterizations of the solid-state reaction between the MMed powders and process control agent (PCA) after the systematically heating from 573 to 873K for 24 h suggested the following products: Formation of γ-Al2O3 was observed in the 4 h MMed powders with heating from 773K for 24 h, whereas the mixture of γ-Al2O3 and Al4C3 was observed in the 32 h MMed powders with heating from 773K for 24 h. No significant microhardness changes in the MMed powders were observed after heating up to 873K for 24 h due to the induced solid-state reaction. TEM observations suggested nanostructured pure aluminum was apparently formed by MM process.抄録全体を表示PDF形式でダウンロード (2005K) -
久保田 正広原稿種別: 研究論文
2012 年 62 巻 11 号 p. 424-428
発行日: 2012/11/30
公開日: 2012/12/30
ジャーナル フリーPure aluminum powders were mechanically milled (MM) using a vibration type of ball mill, and MMed powders were consolidated into bulk materials by the spark plasma sintering (SPS) technique. Changes in hardness and solid-state reactions of the bulk materials have been examined using hardness measurements and X-ray diffraction (XRD), and the mechanical properties and microstructures of the bulk materials have been studied using hardness measurements, compression tests and transmission electron microscopy (TEM). The full density of the bulk materials was obtained with the condition of applied pressure at 15.4 kN at 873K for 1 h. Formation of both γ-Al2O3 and Al4C3 was observed in the bulk materials, and no significant hardness changes in the bulk materials were observed after heating up to 873K for 500 h. The Vickers hardness of the bulk materials fabricated from 0 h and 64 h MMed pure aluminum powders exhibited 39 HV and 180 HV, respectively, and the nominal compressive strength of the bulk materials fabricated from 0 h and 8 h MMed pure aluminum powders showed 80 MPa and 500 MPa, respectively.抄録全体を表示PDF形式でダウンロード (2775K) -
中山 栄浩, 早川 保範原稿種別: 研究論文
2012 年 62 巻 11 号 p. 429-436
発行日: 2012/11/30
公開日: 2012/12/30
ジャーナル フリーPure aluminum (1050) processed by ECAP (Equal-Channel Angular Pressing) and subsequent annealing treatment was subjected to tensile tests to investigate characteristic features of yielding behavior. Dependences of the annealing and test temperatures on the yielding behavior were examined in terms of stress drop and yield point elongation. Relationship between the yield point elongation and geometric configuration of Luder's band was also discussed in detail. Temperature of the annealing treatment had a large influence on the initiation of yielding; steep stress drops and marked yield point elongations occurred for the annealing temperatures at about 530K. Ability of the strain hardening was decreased with increasing the test temperature during the tensile test, while there was no relationship between the stress drop and the testing temperature. Luder's band became shallow with increasing the annealing temperature. The increased ability of the strain hardening due to grain growth led to the formation of Luder's bands that were shallow and easy to propagate.抄録全体を表示PDF形式でダウンロード (3811K) -
松永 哲也, 石渡 薫, 川合 伸明, 佐藤 英一原稿種別: 研究論文
2012 年 62 巻 11 号 p. 437-441
発行日: 2012/11/30
公開日: 2012/12/30
ジャーナル フリーTo reveal grain-size dependency and mechanism of creep of 1050 aluminum at low temperatures, creep tests were performed for the samples with grain sizes (d) of 1.0–47 µm at 233–473K. Dislocation creep rate-controlled by non-diffusion process was observed at low temperatures, i.e., T<400K and 280K for coarse (CG) and ultrafine grained (UFG) specimens, respectively. The former showed creep at more than 0.2% proof stress, whereas the latter did it at less than that stress. Creep behavior of UFG aluminum was similar to ambient-temperature creep of hexagonal close-packed metals because apparent activation energy was about 30 kJ/mol. Although grain-size exponent was small, i.e. p=0–0.3, in CG and UFG regions, transient region was observed at d=1.7–10 µm and creep rate decreased of about one order. At high temperatures, CG and UFG aluminum showed conventional dislocation creep rate-controlled by dislocation-core diffusion.抄録全体を表示PDF形式でダウンロード (3579K) -
中川 惠友, 辻 伸泰, 寺田 大将, 中野 聡彦, Khairul Nizam, 金谷 輝人原稿種別: 研究論文
2012 年 62 巻 11 号 p. 442-447
発行日: 2012/11/30
公開日: 2012/12/30
ジャーナル フリーUsing Vickers hardness measurements and TEM observation, this study investigated the aging behavior of ultrafine-grained (UFG) Al–0.5%Si–0.5%Ge alloy fabricated using six-cycle ARB processing. The hardness of the starting specimen of ultrafine-grained Al–0.5%Si–0.5%Ge alloy is about 2.3 times higher than that of the coarse-grained specimen. The starting UFG specimen showed ultrafine grains with mean size of 156 nm. The hardness of a UFG specimen aged at 473K decreased monotonously with increasing aging time. From TEM observations of the microstructure of UFG specimen aged after long-term aging at 473K, results show that the mean size of ultrafine grains increased significantly with increasing aging time. Furthermore, few precipitates exist inside gains, although many coarse precipitates exist at grain boundaries. The hardness of UFG specimen aged at 373K showed the maximum value. From TEM observations, results showed many elongated ultrafine grains, with many precipitates formed on the grain boundaries and inside grains of the specimens aged at 373K. These results suggest that precipitation hardening strongly affected the hardness in this alloy because it has many elongated ultrafine grains. Many fine Si–Ge precipitates formed inside grains of the UFG specimen aged at 373K in long-term aging.抄録全体を表示PDF形式でダウンロード (4081K) -
赤間 大地, 李 昇原, 堀田 善治, 松田 健二, 廣澤 渉一原稿種別: 研究論文
2012 年 62 巻 11 号 p. 448-453
発行日: 2012/11/30
公開日: 2012/12/30
ジャーナル フリーAge-hardenable Al–Mg–Si alloys containing an additional element of either Ag, Cu, Pt or Pd were processed by high-pressure torsion (HPT) and they were subsequently aged at a temperature of 373K for up to a total period of 5400 ks. It was found that, in all alloys, the grain sizes after HPT were refined to 300–400 nm and there were significant increases in the hardness through the HPT processing. The hardness was further increased by the subsequent aging treatment, confirming the simultaneous strengthening by grain refinement and fine precipitation. However, the aging behavior was different depending on the alloying compositions. In the Cu-added excess Mg alloy, the hardness increase was large and the higher hardness retained for longer aging time when compared with those of non-added alloys. It was suggested that the precipitation of a few particles within a single grain with the size of a few hundred nanometer contributes to appreciable age hardening.抄録全体を表示PDF形式でダウンロード (5835K) -
田添 聖誠, 堀田 善治原稿種別: 研究論文
2012 年 62 巻 11 号 p. 454-458
発行日: 2012/11/30
公開日: 2012/12/30
ジャーナル フリーHigh-Pressure Sliding (HPS) is a new severe plastic deformation process for sheet samples under high-pressure. In this study, the HPS is applied to an age-hardenable 7075 aluminum alloy for grain refinement. HPS was conducted under a pressure of 1 GPa for sliding distances of 7.0 mm at room temperature and for 10 mm at 373K, and thus the average grain size was reduced to ~280 nm and ~240 nm, respectively. Ultimate tensile strength of ~600 MPa was achieved by this grain refinement. Aging at 373K of the HPS-processed samples led to further hardening to 750 MPa. It is shown that simultaneous strengthening due to grain refinement and fine precipitation is achieved in the 7075 aluminum alloy by application of HPS and subsequent aging.抄録全体を表示PDF形式でダウンロード (3579K) -
米本 涼, 有田 誠, 堀田 善治原稿種別: 研究論文
2012 年 62 巻 11 号 p. 459-463
発行日: 2012/11/30
公開日: 2012/12/30
ジャーナル フリーSevere plastic deformation using high-pressure torsion was applied for consolidation of Al/Fe3O4 composites. The consolidation was achieved with the Vickers microhardness saturated to ~240 HV for Al–10 vol%Fe3O4 and to ~300 HV for Al–20 vol%Fe3O4 after processing for 5 revolutions under a pressure of 6 GPa. The density increased with straining and reached the highest after 5–7 revolutions but decreased for further revolutions. The coercive force had the same trend as the density but the saturation magnetization is almost invariable with straining. No appreciable difference was observed between the magnetic fields applied in the directions perpendicular and parallel to the ring plane. Electrical conductivity decreased with straining and this was attributed to generation of a large amount of lattice defects such as grain boundaries.抄録全体を表示PDF形式でダウンロード (4903K) -
上杉 徳照, 東 健司原稿種別: 研究論文
2012 年 62 巻 11 号 p. 464-471
発行日: 2012/11/30
公開日: 2012/12/30
ジャーナル フリーWe studied the relationship between the grain boundary energy and grain boundary excess free volume at the tilt grain boundaries in aluminum by applying the first-principles calculations. The grain boundary energy increased linearly as the grain boundary excess free volume increased. The value of the proportionality constant between the grain boundary energy and the grain boundary excess free volume, α, was 13.8 GPa for aluminum. The grain boundary elastic energy was calculated on the basis of first principles using a dummy boundary as well as the classical elasticity theory. The grain boundary elastic energies are close to the grain boundary energies. We discussed the free volume in nanocrystalline and ultrafine-grained materials and proposed a method for estimating the grain boundary energy using the density of nanocrystalline and ultrafine-grained materials with the proportionality constant, α. The grain boundary energy of nanocrystalline aluminum fabricated by mechanical milling and subsequent consolidation was estimated. The calculated grain boundary energy in the nanocrystalline aluminum is comparable to or lesser than that in coarse-grained aluminum.抄録全体を表示PDF形式でダウンロード (1420K)
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