巻号一覧
45 巻, 2 号
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根岸 祐司, 西村 卓寛, 桐生 雅夫, 鎌土 重晴, 小島 陽, 二宮 隆二1995 年 45 巻 2 号 p. 57-63
発行日: 1995/02/28
公開日: 2008/10/30
ジャーナル フリーThe purpose of this study is a search for compositional ranges available to replace expensive heavy rare-earth elements (Gd, Dy) by a cheaper element such as Nd on keeping the heat resistance. The equilibrium phase diagrams of magnesium-rich portion of ternary alloys are made. Investigated compositional ranges are less than 9 masss%Gd or Dy, and less than 7 mass%Nd, and aging characteristics in such compositional ranges were investigated. Alloys with 3 mass%Nd have a single phase of magnesium solid solution(α-phase)at 535°C, but their solubility limits of Gd or Dy shift largely to lower concentration than those of M-Gd or-Dy binary alloys with decreasing temperature. Even alloys containing the smallest content of heavy rare earth elements such as Mg-3 mass%Gd(Dy)-3 mass%Nd alloys show marked age hardenlng even at 250°C. Aging characterlstlcs, mechanlcal property, and corroslon reslstance of Mg-5, 6, 7 mass%Gd(Dy)-3 mass%Nd alloys with zirconium as a grain refinement agent are evaluated. The remarkable age hardening is found to be caused by the precipitation of matastableβ"-phase with a D019 crystal structure from the results of observation of precipitates using a transmission electron microscope. Heat resistance of quaternary alloys containing more than 6 mass%Gd or Dy, and 3 mass%Nd is better than that of WE54A magnesium alloy. Furthermore, the specific strength of these alloys is as high as about twice of the conventional heat resistant aluminum alloys.抄録全体を表示PDF形式でダウンロード (2127K) -
野口 篤史, 江澤 勲, 金子 純一, 菅又 信1995 年 45 巻 2 号 p. 64-69
発行日: 1995/02/28
公開日: 2008/10/30
ジャーナル フリーSiC particulate dispersed Mg-10%Ce and Mg-5%Ca alloy composites were successfully obtained by using an experimentally constructed spray forming apparatus with simultaneous injection of SiC particles. The spray formed composites showed relative density higher than 95%. The relative density was improved to above 99% by hot extrusion. The uniformity in distribution of dispersed SiC particles was also improved by hot extrusion. It has been shown that fine SiC particles which are even smaller than 1μm in diameter can be dispersed by spary forming technique. The measured Vf of SiC particles in spray formed and hot extruded materials increased with an increase of the average particle size. The obtained Vf of coarse SiC particles which is 12μm in average size was as high as 18.8%. The elastic modulus and hardness were appreciably increased by dispersion of SiC particles. However, improvement in tensile strength was not observed in the composites.抄録全体を表示PDF形式でダウンロード (1530K) -
朝比奈 敏勝, 時末 光1995 年 45 巻 2 号 p. 70-75
発行日: 1995/02/28
公開日: 2008/10/30
ジャーナル フリーAZ31 magnesium alloy plates 4mm in thickness were welded without addition of filler wire using a pulsed AC TIG welding machine. Microstructural observations have been carried out together with the mechanical tests on the welded joints, with the special reference to the effects of pulse frequency on the optimum welding conditions. In case of the pulse frequency of 20Hz, the crystal grains of the fusion zone are most fine. The hardness of the fusion zone of welded joints are nearly equal to that of the base metal. The welded joints without pulse have the same tensile strength and elongation as those of the base metal. The highest tensile strength and elongation of pulsed welded joints can be obtained with the pulse frequency of 20Hz, but they are inferior to those of the base metal. All the welded joints are fractured at the center of the fusion zone regardless of the pulse frequency. The bending angle of welded joints is smaller than that of the base metal. Fatigue limit of the welded joints with the pulse frequency of 20Hz is 92% of the base metal. And the fatigue limit of the pulse welded joints depends on the grain size of the fusion zone.抄録全体を表示PDF形式でダウンロード (1206K) -
吉川 克之, 坂本 敏正, 古川 隆夫, 美蔦 芳宏1995 年 45 巻 2 号 p. 76-81
発行日: 1995/02/28
公開日: 2008/10/30
ジャーナル フリーThe formation mechanism of brittle and coarse giant intermetallic compounds in Al-Zn-Mg-Cu alloys, corresponding to the 7075 alloy, has been investigated. Giant intermetallic compounds are found to be a CrAl7 phase into which Mn and Ti dissolve, and they crystallize as primary crystals prior to the crystallization of α-Al. The primary crystallization field and the crystallization temperature, T (°C), of the CrAl7 phase are presented by [%Mn] + 3.25 [%Cr] = 0.682 (at 637.5°C) and T = 600.9+53.70 ([%Mn] + 3.25 [%Cr]), respectively. The influence of Zn, Mg and Cu on the -primary crystallization field of the Cr compounds is found to be rather small. Applying these equations, it is possible to predict and prevent the precipitation of the compounds during solidification. The addition of Zr to the 7075 alloy also causes the precipitation of the Zr primary compound of (Zr, Ti) Al3.抄録全体を表示PDF形式でダウンロード (879K) -
森本 啓之, 岩村 宏, 大内 権一郎, 芦田 喜郎1995 年 45 巻 2 号 p. 82-87
発行日: 1995/02/28
公開日: 2008/10/30
ジャーナル フリーAn attempt was made to fabricate thin wall tubes of SiC whisker reinforced 6061 aluminum alloy composite with 1mm thickness, by adopting a hot hydrostatic extrusion. The composite billets were fabricated with a powder metallurgical process and then extruded at a high extrusion ratio. Thin wall tubes with good surface quality, high strength and Young's modulus, and high Weibull modulus were fabricated, through optimization of extrusion conditions such as billet temperature, tool temperature, billet surface roughness and extrusion speed. The billet microstructure was composed of two regions: the high whisker volume fraction region and the whisker-free aluminum alloy region. The extrusion elongated and dispersed the high whisker volume fraction region, resulting in a decrease in the size of this region perpendicular to the extruding direction. The increase in uniformity of whisker dispersion is the major reason for the increase in Weibull modulus, or an improvement in reliability due to extrusion. It was demonstrated that the higher temperature extrusion is a usefull process for fabrication of high quality composite.抄録全体を表示PDF形式でダウンロード (1766K) -
小林 俊郎, 新家 光雄, 原田 俊宏, 下村 勇一, 伊藤 利明1995 年 45 巻 2 号 p. 88-94
発行日: 1995/02/28
公開日: 2008/10/30
ジャーナル フリーThe effects of Fe and Ca additions on impact fatigue characteristics were investigated comparing with their effects on usual fatigue characteristics in AC2B-T6 aluminum casting alloys. Impact fatigue strength in the low cycle life region of a low Fe content sample is greater than that of the high Fe content one. This trend is, however, just opposite to the trend in the high cycle life region. Both impact and usual fatigue strengths, especially in the high cycle life region, increased by refining and spheroidizing of eutectic Si particles and refining of Al-Fe based intermetallic compounds by adding small amount of Ca. They were confirmed by fractographic observation of fatigue crack around eutectic Si particles and Al-Fe system intermetallic compounds on the fatigue fracture surface. The usual fatigue strength is greater than the impact fatigue strength when fatigue strength is characterized by the cumulative duration time of loading.抄録全体を表示PDF形式でダウンロード (1871K) -
松田 健二, 寺崎 稔, 多々 静夫, 池野 進1995 年 45 巻 2 号 p. 95-100
発行日: 1995/02/28
公開日: 2008/10/30
ジャーナル フリーThe effects of deformation and pre-aging on age-hardening of Al-Mg2Si alloys containing 0.4mass% excess silicon were investigated by Vickers micro-hardness test and transmission electron microscope observation. The time required to reach a maximum value of age-hardening curve (tmax) was shortened by deformation just prior to aging for all alloys. The maximum hardness value (Hmax) increased with increasing the amount of deformation in an 0.4%Mg2Si alloy aged at 473K. The precipitates became finer by the deformation prior to aging. The Hmax, values were independent of the amount of deformation and were constant for alloys containing Mg2Si ranged from 0.6 to 1.0%. For those alloys, the size of precipitates was larger and the number of precipitates was reduced by the addition of deformation. The tmax at 473K was shortened by pre-aging at 423K before deformation in an 0.6%Mg2Si alloy. The pre-aging and deformation treatment has also the effect to increase the Hmax to a higher value equivalent to that obtained by the conventional aging at 423K.抄録全体を表示PDF形式でダウンロード (1700K) -
宮永 徹夫, 菱川 滋, 小林 博幸1995 年 45 巻 2 号 p. 101-114
発行日: 1995/02/28
公開日: 2008/10/30
ジャーナル フリーPDF形式でダウンロード (2624K) -
大原 欽也1995 年 45 巻 2 号 p. 115-116
発行日: 1995/02/28
公開日: 2008/10/30
ジャーナル フリーPDF形式でダウンロード (232K) -
里 達雄1995 年 45 巻 2 号 p. 117-119
発行日: 1995/02/28
公開日: 2008/10/30
ジャーナル フリーPDF形式でダウンロード (399K)
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