鋳造工学
Online ISSN : 2185-5374
Print ISSN : 1342-0429
ISSN-L : 1342-0429
89 巻, 3 号
選択された号の論文の6件中1~6を表示しています
研究論文
  • 董 樹新, 岩田 靖, 杉山 義雄, 岩堀 弘昭
    2017 年 89 巻 3 号 p. 111-118
    発行日: 2017/03/25
    公開日: 2017/04/03
    ジャーナル フリー

      To ensure dimensional precision in various service environments, this study investigated the strain variation of JIS ADC12 aluminum alloy die castings by heat treatment and its relation with the strain (hereinafter, growth) arising from the precipitation of silicon, copper, and magnesium.

      Expansion strain exceeding 0.1% was produced in a JIS ADC12 aluminum alloy die casting by heat treatment. Simultaneously, the half-width angles of the X-ray diffraction (XRD) peaks of the aluminum phase in the die casting decreased. Silicon, copper, and magnesium concentrated phases appeared in the aluminum phase after heat treatment. Consequently, the decrease in the half-width angles can be regarded as a result of the improved crystallinity of the aluminum phase because of the relaxation of the lattice strain by the precipitation of silicon, copper, and magnesium. That is to say, the strain variation of the ADC12 alloy die casting by the heat treatment is attributable to the precipitation of silicon, copper, and magnesium from the supersaturated aluminum phase. To verify the above relation quantitatively, growth attributable to the precipitation of silicon, copper, and magnesium from the aluminum phase and the transformation of the precipitated metastable Cu-Al compounds was estimated theoretically and compared with the measured strain variation yielded by heat treatment of the ADC12 alloy die casting. Results confirmed that the strain variation of the ADC12 alloy die casting by heat treatment corresponded fairly well to the growth arising from the precipitation of silicon, copper, and magnesium out of the aluminum phase and the transformation of the precipitated metastable Cu-Al compounds. Results also show that silicon, copper and magnesium precipitated at an early stage of heat treatment and that the silicon precipitation contributed mostly to the growth. The precipitated metastable Cu-Al compound, θ", was found transformed to another metastable compound, θ', and stable compound, θ, sequentially, thereby giving some expansion and contraction growth.

  • 永瀬 丈嗣, 武村 守, 松室 光昭, 丸山 徹
    2017 年 89 巻 3 号 p. 119-129
    発行日: 2017/03/25
    公開日: 2017/04/03
    ジャーナル フリー

      AlCoCrFeNi2.1 eutectic high entropy alloy (HEA) ingots were successfully obtained by high-frequency melting and centrifugal metallic mold casting under Ar flow. The microstructure of the ingots was investigated by trans-scale observations using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM). The constituent phases of the ingots were identified as fcc and bcc phases by X-ray diffraction (XRD) analysis, and were not dependent on the position of the ingots. In particular, dendrite fcc and inter-dendrite fcc and bcc eutectic structures were observed, regardless the position of the ingots. The solidification structure was affected by cooling. Faster cooling rates resulted in finer solidification structures. TEM observations clarified the development of L12 ordering structures in the dendrite fcc phase, while the ordering peak could not be detected by XRD analysis.

  • 松木 俊朗, 藤野 知樹, 後藤 仁, 村上 周平, 髙橋 俊祐
    2017 年 89 巻 3 号 p. 130-135
    発行日: 2017/03/25
    公開日: 2017/04/03
    ジャーナル フリー

      The influence of alloy elements and cooling rate on the as-cast hardness of spheroidal graphite iron was studied for obtaining fundamental knowledge on controlling hardness.

      The effects of manganese, copper and tin were compared as alloying elements, and the results showed that the pearlite area ratio of the matrix increases when copper and/or tin is added, and Brinell hardness was also higher.

      The results of investigating the relationship between cooling rate before eutectoid transformation (at 1073 K) and Brinell hardness indicated a linear relationship between the logarithm of the cooling rate and the hardness. The difference in hardness according to the cooling rate is considered to be caused by the interlamellar spacing of pearlite and the amount of carbon in the matrix.

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