軽金属
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
41 巻, 8 号
選択された号の論文の10件中1~10を表示しています
  • 穴田 博, 越本 普弘, 多々 静夫, 堀 茂徳
    1991 年 41 巻 8 号 p. 497-503
    発行日: 1991/08/30
    公開日: 2008/10/30
    ジャーナル フリー
    The feathery crystal billets in Al-Mg alloys were solidified by using "Graphite Mold Submerging (GMS) process", which is that the graphite mold filled with molten metal is constantly submerged into water directly and the solidifying rate and cooling rate can be controlled by combining descending speed of mold and casting temperature. The changes of the spacing or direction of twin boundaries in each feathery crystal billet were examined microscopically. Features of twin boundaries are as follows: (1) The twin boundary spacing decreases with the increase of solute concentration and solidifying rate and is little affected by the temperature gradient. (2) Immediately after the generation of feathery crystals, the mean spacing of twin boundary λ increases temporarily under any circumstance. (3) In the stable growth state, the angle θ between the twin boundary and the billet axis and λ tends to become lager at the periphery than at the center of the billet.
  • 小川 恒一, 上田 淳, 加賀 精一, 山口 博
    1991 年 41 巻 8 号 p. 504-509
    発行日: 1991/08/30
    公開日: 2008/10/30
    ジャーナル フリー
    A high strength aluminum alloy A7075 was examined for the friction welding under the condition of the 24 factorial design. Friction pressure, friction time, forging pressure and rotating speed were took into account for the friction welding factors. Strong correlation was found between forging pressure and joint strength as well as between terminal peak torque and joint strength.
  • 小松 伸也, 池田 勝彦, 筑田 昌宏, 小林 紘二郎
    1991 年 41 巻 8 号 p. 510-514
    発行日: 1991/08/30
    公開日: 2008/10/30
    ジャーナル フリー
    A relation between the resistance ratio (R30077) and the resistivity at 77K (ρ77) deduced from Matthiessen's rule and empirically determiend for commercial pure aluminium was applied to Al-1-15%Si cast alloys. ρM77 and size factor M.F. according to Matthiessen's rule were calculated from the resistance ratio R using the empirical relation. Both the geometrical size factor G.F. and resistivity ρG77 obtained using the conventional method were compared with the M.F. and ρM77•ρM77 was always smaller than ρG77, and well corresponded to the change in solute Si concentration caused by heat treatment. Volume fraction of precipitated Si approximately estimated from a ratio of the two size factors, M.F./G.F., was nearly 3 times higher than that estimated from the ρM77 and Si content. To explain this large discrepancy, the current screened areas (S.A.) was proposed to exist in front and behind of precipitated Si particles. The increase in M.F./G.F. during isochronal heat treatment could be qualitatively explained by the decrease in the S.A. resulting from the rapid dissolution of smaller Si particles. Taking account of the effects of shape and distribution of Si particles on the S.A., the change in the contribution of precipitates to the resistivity is also understood.
  • 山村 謙, 佐治 重興, 久 正明, 堀 茂徳
    1991 年 41 巻 8 号 p. 515-521
    発行日: 1991/08/30
    公開日: 2008/10/30
    ジャーナル フリー
    Temperature dependence of tensile properties and fracture morphorogy were investigated in the temperature range from 7 to 293K for the as-quenched and peak-aged specimens of Al-2 mass%Li-0, 1, 2 mass%Mg alloys. The increase in the proof stress with decreasing temperature in the as-quenched specimens was explained in terms of the short-range interactions between dislocations and the solute atoms, whereas the small temperature dependence of the proof stress in the peak-aged specimens was explained in terms of the long range interactions between dislocations and δ'-Al3Li precipitates. Constant tensile strength at very low temperatures (<-40K) was due to the grain boundary fracture. The increase in both the elongation to fracture and toughness defined as the work done for fracture with decreasing temperature to about 20K was attributed to the increasing difficultes of cross slip of dislocations as temperature decreased for an Al-Li binary alloy. The decrease in both the properties with decreasing temperature was due to both the acceleration of intergranular fracture and the increase in strain hardening with decreasing temperature. Magnesium addition to Al-Li alloys enhanced both the intergranular fracture and strain hardening, which resulted in the decrease in elongation and toughness with decreasing temperature.
  • 坂本 健, 瀬尾 真浩, 佐藤 教男, 慈道 文治, 難波江 元広, 古谷 修一
    1991 年 41 巻 8 号 p. 522-527
    発行日: 1991/08/30
    公開日: 2008/10/30
    ジャーナル フリー
    Both the titanium oxide, TiO2 and chromium oxide, Cr2O3 were deposited on aluminum substrate with alkoxid-CVD to improve the pitting corrosion resistance in neutral aqueous solution. Titanium tetrasopropoxide, Ti(C3H7O)4 and chromium acetylacetonate, Cr(C5H7O2)3 were employed as evaporation sources for TiO2 and Cr2O3, respectively. The deposition of oxides was performed at a deposition rate of about 60nmh-1 under controlled mass flow rates (200sccm and 500sccm) of nitrogen carrier gas at different substrate temperatures (373K to 573K for TiO2 and 703K for Cr2O3), and at different evaporation source temperatures (298K and 343K for TiO2 and 433K and 513K for Cr2O3). Particularly, for the deposition of Cr2O3, water vapor at 353K was added to nitrogen carrier gas to promote the deposition. The Auger analysis in depth indicated that aluminum of oxidation state is present in the interface layer between deposited oxide and aluminum substrate for both oxides. Furthermore, the ellipsometrical results suggested that the deposited oxides were amorphous. It was found that the average pitting potential of aluminum in pH 8.4 boric-borate solution containing 10-2mol dm-3 Cl- ions increased by 1.5V due to the surface coating of both oxides with thickness of 40nm.
  • 二宮 崇, 長 隆郎
    1991 年 41 巻 8 号 p. 528-533
    発行日: 1991/08/30
    公開日: 2008/10/30
    ジャーナル フリー
    Wettability of alumina fibres containing 15%SiO2 to liquid aluminum alloys were measured using a dip coverage method, dipping a bundle of fibres into liquid metal. The wetting process could be analyzed by the same model applied in the previous work. Although the value of overall reaction rate constant k0 for fibre dipped into pure aluminum at 1273K slightly decreased, the incubation time increased considerably comparing with that for block. On the other hand, the value of k0 for fibre to Al-Ca system alloy at 1273K increased higher than that of block. These experimental results were explained based on the Wenzel's rule describing the effect of the roughness of solid/melt interface on the wettability. Calcium and magnesium additions improved the wettability at 1023K by forming their oxides or silicide at or near the interface. On the other hand, silicon showed an inferior effect on the wettability. The dependence of the wettability of fibre to a Al-3%Ca alloy on temperature gave the activation energy of 335kJ/mol, which was almost the same as the single binding energy of Si-O of 370kJ/mol. Therefore, the wetting process of alumina fibre containig 15% SiO2 is possibly controlled by the rate of dissociation of SiO2.
  • 土公 武宣, 浅見 重則, 戸次 洋一郎, 松本 英幹
    1991 年 41 巻 8 号 p. 534-540
    発行日: 1991/08/30
    公開日: 2008/10/30
    ジャーナル フリー
    In order to investigate subgrain formation and precipitation in a 1100 aluminum alloy during hot-rolling process, DC cast ingots were subjected to four conditions of homogenization and then multi-pass hot-rolling. The size of subgrains formed during hot-rolling changed depending on the condition of rolling pass through Z-parameter, but was not affected by both the distribution of precipitates and the amout of solid solution determined by the homogenizing condition. Precipitation took place during hot-rolling. Precipitates were considered to be preferentially formed during rolling, but not formed during holding period between passes. In the present range of temperatures, the amount of precipitates increased with decreasing rolling temperature. The precipitates formed in the matix during homogenization resulted in the enhanced precipitation during rolling.
  • 増田 千利
    1991 年 41 巻 8 号 p. 541-549
    発行日: 1991/08/30
    公開日: 2008/10/30
    ジャーナル フリー
  • 加藤 周一郎
    1991 年 41 巻 8 号 p. 550-560
    発行日: 1991/08/30
    公開日: 2008/10/30
    ジャーナル フリー
  • 高山 善匡
    1991 年 41 巻 8 号 p. 561-562
    発行日: 1991/08/30
    公開日: 2008/10/30
    ジャーナル フリー
feedback
Top