日本金属学会誌
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
最新号
選択された号の論文の2件中1~2を表示しています
レビュー
  • 岩崎 宗将, 田邉 匡生
    原稿種別: レビュー
    2025 年 89 巻 2 号 p. 143-151
    発行日: 2025/02/01
    公開日: 2025/01/25
    [早期公開] 公開日: 2024/12/13
    ジャーナル フリー HTML

    Non-destructive and non-contact measurement technology using terahertz waves is expected to solve social issues such as aging infrastructure facilities and promotion of plastic container recycling. However, devices capable of high-sensitivity detection at room temperature, which is necessary for social implementation, have not yet been commercialized, and our laboratory is constructing a terahertz wave measurement system with the aim of social implementation of nondestructive and non-contact inspection using terahertz wave devices. Focusing on materials, they are also developing device materials to increase the sensitivity of detection devices. In a study on nondestructive inspection of concrete structures, it was confirmed that the location and degree of corrosion of reinforcing steel bars at a cover thickness of 10 mm inside the concrete can be estimated by terahertz reflection measurement. In a study on non-contact identification of plastics, it was confirmed that transmission measurements in the sub-terahertz band around 0.3 THz and in the terahertz band above 1 THz can not only identify the type of plastic, but also provide information on additives in transmission measurements from 1 THz to 6 THz. As a result of material development, organic triglycine sulfate (TGS) crystals used as infrared detector elements were grown from saturated solution by solvent evaporation method and irradiated with 40 GHz electromagnetic waves in the sub-terahertz band during crystal growth. As a result, the crystal growth rate was doubled compared to the non-irradiated condition, and the crystal structure was further changed. The new result that crystal growth is promoted by irradiation of electromagnetic waves in the sub-terahertz band is expected to lead to the proposal of a new crystal growth method using electromagnetic waves in the terahertz band. The non-contact, nondestructive measurements and material development data outlined in this paper provide the basis for future terahertz applications.

論文
  • 武藤 有輝, 三宅 淳司, 倉敷 哲生, 森 裕章
    原稿種別: 論文
    2025 年 89 巻 2 号 p. 152-159
    発行日: 2025/02/01
    公開日: 2025/01/25
    ジャーナル フリー HTML

    The effect of additive elements on the microstructure after unidirectional solidification of Cu-Ni-Si alloys (Corson alloys), which is necessary for the prediction of the hot–cracking susceptibility, was studied. The relationship between dendrite structure and cooling conditions was investigated for Cu-4.5Ni-1.07Si and Cu-2.3Ni-0.55Si. It was shown that these primary and secondary dendrite arm spacings (P- and S-DASs) could be accurately predicted with a power approximation for the cooling conditions regardless of the compositions. Scanning electron microscopy revealed that Ni2Si phases were observed only for Cu-4.5Ni-1.07Si. The effect of the additive elements on the Ni2Si phase formation was simulated. The calculated phase fraction of Ni2Si at the end of solidification agreed with the value observed in the experiments. The simulations for the various compositions predicted the solid fractions at which the Ni2Si phases initiated to form. Based on the idea that the secondary phase formations promote dendrites branches to contact tightly each other, we estimated the solid fraction ranges of the dendrite-contacting and also the range of additive element compositions, in which Ni2Si phase formation must be considered for the determination of the coalescence solid fraction for Corson alloys.

feedback
Top