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真中 俊明, 伊藤 吾朗2017 年 67 巻 3 号 p. 67-71
発行日: 2017/03/30
公開日: 2017/04/30
ジャーナル フリーWith respect to hydrogen embrittlement process in a 7075 alloy in humid air, it has been claimed that cracks at second-phase particles result in intergranular cracking. In this study, slow strain rate tensile tests in two environments and microscopic surface observation were carried out to investigate the hydrogen embrittlement process of a 7075 alloy. It was confirmed that elongation in humid air was smaller than in dry nitrogen gas due to hydrogen embrittlement. In both environments, cracks were observed in second-phase particles on the specimen surface during tensile deformation. The amount of cracks in second-phase particles was not larger in humid air than in dry nitrogen gas. Moreover, they did not grow into the aluminum matrix in both environments. Some intergranular cracks were observed on the specimen surface without a cracking of second-phase particles in humid air. Therefore, hydrogen embrittlement in a 7075 alloy based on intergranular cracking in humid air is not caused by a cracking of second-phase particles on the specimen surface.
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塩田 正彦, 馬渕 豊2017 年 67 巻 3 号 p. 72-78
発行日: 2017/03/30
公開日: 2017/04/30
ジャーナル フリーThe wear behavior of hyper-eutectic Al–Si alloys against bearing steels was investigated under the lubricated condition. The severe-mild wear transition of hyper-eutectic Al–Si alloys occurred when Si-particle size or area ratio exceeded critical values. Below the critical value, Al–Si alloys still remained in the sever wear mode resulting in a large amount of wear due to the insufficient sparse distribution of primary Si phase at the contact area.
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高橋 成也2017 年 67 巻 3 号 p. 79-86
発行日: 2017/03/30
公開日: 2017/06/30
ジャーナル フリーPDF形式でダウンロード (1492K)
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