巻号一覧
46 巻, 8 号
選択された号の論文の7件中1～7を表示しています
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研究論文
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大西 脩嗣, 鷹合 徹也, 中山 栄浩, 二ノ宮 克成1996 年 46 巻 8 号 p. 365-370
発行日: 1996年
公開日: 2007/03/30
ジャーナル フリーEffect of casting condition, especially of cooling rates, on the microstructures and mechanical properties of the AC4CH aluminum casting alloy has been investigated and the following results were obtained. Clear effect of the cooling rate on the dendritic structures was observed and reasonable linear relation between log DAS (dendrite arm spacing) and log R (cooling rate) was ascertained. In case of copper mold application, higher cooling rate dependence was obtained for the growth of the dendrite as compared to that of iron mold. Increase of the cooling rate resulted in an effective refining of the eutectic silicon phase, while a weak influence was observed on the spheroidization coefficient of the eutectic silicon. Effect of the cooling rate on the tensile strength was remarkable under the conditions of under-aging and over-aging. Higher values of the absorbed energy in the Charpy impact fracture were obtained by applications of the copper mold. Increase of the cooling rate raised magnesium concentration in the matrix. Above all, higher magnesium concentrations were certainly obtained for the copper mold applications as compared to those of iron mold.抄録全体を表示PDF形式でダウンロード (833K) -
隠岐 貴史, 松木 一弘, 畑山 東明, 柳沢 平1996 年 46 巻 8 号 p. 371-376
発行日: 1996年
公開日: 2007/03/30
ジャーナル フリーThe relationship between the microstructures and tensile propertie has been investigated for the vacuum sintered and vacuum sintered plus HIP'ed Ti–6 mass%Al–4 mass%V (Ti–6–4) which are produced by blending pure titanium powders with Al–42 mass%V master alloy powders. The microstructure changes with vacuum sintering temperatures and is classified into two types, (1) Type 1: For materials sintered at temperatures below 1400 K, the microstructure consists of lenticular α-phase plates with relatively low aspect ratio, and β phase. (2) Type 2: For materials sintered at temperatures above 1400 K, the microstructure consists of α/β lamellar surrounded by grain boundary α-phase. For the materials of type 1, density, tensile stress and ductility increase with increasing sintering temperature. On the other hand, for the materials of type 2, density and tensile stress increase monotonously with increasing sintering temperature but ductility decreases with increasing temperature to 1473 K and increases above this temperature. Higher densification and improvement of tensile properties are achieved by HIP treatment for the materials sintered in vacuum at temperatures above 1273 K. Microstructure of the HIP'ed materials above the β transus is that of type 2 and ductility decreases with increasing average size of grain boundary α-phase. The materials, HIP'ed below the β transus with the microstructure of type 1 show excellent 0.2% proof stress, tensile stress and ductility. It is concluded that HIP treatment (1073–1173 K) below the β transus is effective for obtaining microstructure of type 1, which leads to the improvement of the tensile properties.抄録全体を表示PDF形式でダウンロード (1087K) -
加藤 鋭次, 野村 宏之, 大城 直人1996 年 46 巻 8 号 p. 377-382
発行日: 1996年
公開日: 2007/03/30
ジャーナル フリーThe effect of phosphorus on the silicon particle structure during solidification has been investigated for Al–Si eutectic alloy. Phosphorus content less than about 5 ppm refines the microstructure. The eutectic silicon exhibits a very finely divided lamellar structure. A few dendrites of primary aluminum crystal are also observed showing a slightly hypoeutectic behavior for this composition. For phosphorus content not less than 10 ppm, the coarsening of eutectic structure was observed. Then coarse crystals of plate-like silicon appear and the eutectic silicon of acicular shape becomes much coarser than that in the case of the pure alloy. Al–12.5%Si alloy containing phosphorus forms small crystals of aluminum phosphide in the molten aluminum before solidification, which act as effective nuclei for silicon and promote crystallisation of plate-like silicon at the start of solidification. The fact that undercooling of eutectic solidification becomes smaller for phosphorus containing alloy supports the above idea.抄録全体を表示PDF形式でダウンロード (1307K) -
Kiyotaka MATSUURA, Toshiki KITAMURA, Masayuki KUDOH1996 年 46 巻 8 号 p. 383-388
発行日: 1996年
公開日: 2007/03/30
ジャーナル フリーSeveral Al–Ni alloys containing 20 to 80 at% nickel are produced from a mixture of aluminum and nickel powders by a combustion synthesis method using a pseudo-HIP (Hot Isostatic Pressing) process. All the powder mixtures exothermically react and produce intermetallic compounds. The change in the exothermic temperature resulting from the composition of the powder mixture seems to be similar to the change in the melting temperature of the alloy. When the nickel content of the powder mixture is below 30 at% or above 70 at%, the multiphase structure including the elemental phase is formed. When an intermetallic compound phase has a relatively wide concentration range, the monophase structure of the compound is formed. The Vickers hardness of the synthesized alloy which include the elemental phase is 100 to 200 at room temperature. The hardness of Ni2Al3 is above 700. The hardness of NiAl changes with the nickel content; it decreases from 400 to 300 as the nickel content increases from 46 to 50 at%, but it increases to 400 as the nickel content increases from 50 to 56 at%.抄録全体を表示PDF形式でダウンロード (1155K) -
藤野 隆由, 奥村 克太郎, 野口 駿雄, 吉村 長蔵1996 年 46 巻 8 号 p. 389-394
発行日: 1996年
公開日: 2007/03/30
ジャーナル フリーPhysical properties and compositions of hard coatings formed by AC process were investigated in comparison with those by DC process. Electrolysis was carried out at current density 3 A/dm2 and at bath temperature 10-20°C, using a sulfuric acid solution containing chromic acid ion (potassium dichromate, chrome (VI) oxides and oxide powders (aluminum oxide, glass beads). Addition of both potassium dichromate and glass beads provided the best properties in hardness for the AC process films by their combined effects, while the hardness and abrasion properties were improved by the addition of chromic acid ion and oxide powders. These characteristic features are thought to result from an increase in aluminum content in the film by the addition of chromic acid, and also from the levelling of the film surface caused by the addition of oxide powders. But AC process films generally showed lower hardness than DC process films. It is considered, on the basis of AAS, EPMA and SIMS analyses, that this lower hardness is attributable to a smaller amount of aluminum oxide contained in AC process films.抄録全体を表示PDF形式でダウンロード (890K)
解説
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渡辺 義見, 福井 泰好1996 年 46 巻 8 号 p. 395-403
発行日: 1996年
公開日: 2007/03/30
ジャーナル フリーPDF形式でダウンロード (1589K)
連載講座
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世利 修美1996 年 46 巻 8 号 p. 404-409
発行日: 1996年
公開日: 2022/02/15
ジャーナル フリーPDF形式でダウンロード (5285K)
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