巻号一覧
49 巻, 4 号
選択された号の論文の6件中1～6を表示しています
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研究論文
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河部 昭雄, 押田 篤, 小林 俊郎, 戸田 裕之1999 年 49 巻 4 号 p. 149-154
発行日: 1999年
公開日: 2007/06/01
ジャーナル フリーThe fabrication of metal matrix composite (MMCp) by vortex process is the general method due to the advantage of its convenience. However in the case of fine particles the surface property of the particle appears dominantly, especially in nano-size particles the agglomeration occurs and the fabrication of MMCp is reduced to be difficult. It is analyzed that the strength of the MMCp is dominated by the ascent of the dislocation density. Further, as the dispersion strengthening mechanism can be anticipated, dispersions of more fine particles into the matrix are required. In this study, the influences on various primary factors for solving an agglomeration problem are examined using SiC particles of 0.3 μm (the minimum diameter in the market) into 6061 Al alloy by the vortex method. From this study, the following results are obtained, (1) It is found that MMCp with no agglomeration can be fabricated by conducting the following procedure; pre-treatment, disagglomeration of powder, Ca addition and stirring in the semi-solid range. (2) It is deduced that the main factors of forming the agglomeration in the matrix of MMCp are the yield of SiO2 on the surface of SiC and the reduction of the void ratio of SiC powder.抄録全体を表示PDF形式でダウンロード (1405K) -
崔 祺, 大堀 紘一1999 年 49 巻 4 号 p. 155-160
発行日: 1999年
公開日: 2007/03/30
ジャーナル フリーThe evolution of microstructure and texture of 1050 aluminum sheets was investigated by the method of equal channel angular pressing (ECAP). Repetitive pressings were used on the same samples, up to a total of 8 pressings through the die, with the samples pressed following two different processing routes either without rotation (route A) or with rotation through 180° (route B). The result shows that the high angle grain boundaries increase, and the grain sizes are reduced with repetitive pressings. The rate of formation of the high angle grain boundaries depends upon the processing routes and is more rapid using route A than using route B. Moreover, the shear texture, composed of {001}<110> and {111}<110> components, was observed after 1 pressing. However, the texture, {001}<010> component specially, is reduced with the repetitive pressings. Such a change of texture does not depend upon the processing routes nearly. By subsequent annealing, the intensity of the {111}<110> component is not almost changed, but that of {001}<110> component decreases largely and no new texture component appears.抄録全体を表示PDF形式でダウンロード (971K) -
箕田 正, 吉田 英雄, 都筑 隆之1999 年 49 巻 4 号 p. 161-165
発行日: 1999年
公開日: 2007/03/30
ジャーナル フリーA new process of producing airplane frames was designed to reduce the costs. In this new process, 7475–W aluminum alloy sheets followed by reversion heat treatment (RHT) were used before roll formings instead of 7475–O ones. In this process, the hardness of the sheets after RHT should be below HV120, which was the limit hardness of roll forming. The most suitable condition of RHT, 453 K–40 s was recommended in this study. But the hardness after RHT wasn't reduced to the as-quenched condition. Furthermore, the hardness of the as-quenched specimen followed by RHT was raised to HV110 level. It was confirmed that copper addition reduces the precipitating temperature of η′ and η phase in the Al–Zn–Mg alloy. Then it was suggested that the dissolution of GP Zones and precipitation of η′ and η phase occurred simultaneously in 7475–W aluminum alloy sheet at the reversion heat treatment of 453 K–40 s.抄録全体を表示PDF形式でダウンロード (1097K) -
高橋 明宏, 小林 俊郎, 戸田 裕之1999 年 49 巻 4 号 p. 166-171
発行日: 1999年
公開日: 2007/03/30
ジャーナル フリーIn-situ SEM observations of specimen surfaces during a 3-point bend test have been made to characterize the microscopic damage initiation and the fracture behavior of an Al–Li system alloy. Damage initiation from inclusion particles larger than several micrometers is always attributed to their breakage. Neither interfacial debonding nor interfacial cavitation is observed for such coarse particles. Some kinds of such coarse inclusion particles are fractured several hundred micrometers ahead of a main crack tip. Simultaneous extension of microcracks and the main crack, and subsequent incorporation of the microcracks into the main crack are observed. In such a way, it is clarified that the fracture of the Al–Li alloy is significantly affected by the coarse inclusions. A combination of HRR singularity and Eshelby type internal stress analysis has been used to calculate the actual fracture strengths of various inclusion particles. Fracture strength of both CuAl2 and Al2CuMg particles is about 710 MPa for the diameter ranging 5 and 8 μm, and the fracture strength decreases with increasing particle size. Damage initiation in Al3Zr and Al3Ti particles has not been observed in this study. The lower bound values of the fracture strength of these two kinds of particles are estimated as 900∼1000 MPa by the same analysis.抄録全体を表示PDF形式でダウンロード (1572K) -
梅原 博行, 高谷 松文, 伊藤 哲司1999 年 49 巻 4 号 p. 172-177
発行日: 1999年
公開日: 2007/03/30
ジャーナル フリーThe high purity magnesium alloy AZ91D has demonstrated superior corrosion resistance to the atmosphere, when compared with commercial alloys previously available. Magnesium is anodic to all other engineering metals and has no defense against galvanic corrosion when a magnesium-dissimilar metal assembly is exposed to salt water or other electrolyte. Although galvanic couples are unavoidable in most practical applications of magnesium, there are very few reports about galvanic corrosion of magnesium alloys coupled to other metals. Atmospheric galvanic corrosion test was done to get basic data about the galvanic corrosion behavior of magnesium alloys coupled to dissimilar metals and alloys. This paper reports the results of atmospheric galvanic corrosion test of magnesium alloy AZ91D coupled to a number of dissimilar metals and alloys in Asahikawa, Choshi, Miyakojima and Kayamajima. According to our result this time, it appears the mild steel and SUS304 stainless steel accelerate and anodized aluminum alloys reduce a galvanic corrosion of magnesium alloys. And the corrosion area of atmospheric galvanic corrosion of magnesium alloys were in and around dissimilar metals. We obtained similar results by electrochemical measurements in chloride solution of the magnesium alloy AZ91D and mild steel or SUS304 stainless steel.抄録全体を表示PDF形式でダウンロード (1206K)
解説：小山田記念賞
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山縣 裕, 小池 俊勝1999 年 49 巻 4 号 p. 178-182
発行日: 1999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 (1243K)
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