Rod-lamella transition in directionally solidified Ni-W eutectic alloy

Makoto Yoshida, Takao Tsujimura, Toru Tsukagoshi, Hideo Nakae

    Research output: Contribution to journalArticle

    1 Citation (Scopus)

    Abstract

    The mechanism of rod to lamella transition with increasing growth rate was studied. The relationship between γ phase 〈100〉 direction and the α-phase microstructure was examined using the back-reflection Laue method. The influence of growth rate on the transition was also estimated by increasing the rate in the middle of directional solidification. The experimental results revealed that both the growth rate and the deviation of γ 〈100〉 from the growth direction amplified the aspect ratio of the transverse α-phase microstructure. A mechanism of the transition was proposed and summed up as follows. At first, we assume that the following two control factors exist for the decision of the microstructure: (1) tendency to organize low energy habit planes. (2) eutectic second phase tends to grow perpendicular to the S/L interface (parallel to the growth direction). If no confliction between the two tendencies occurs at the S/L interface, a rod structure will be formed. However, when the derivation of γ 〈100〉 from the growth direction exists, the rod structure will induce the confliction between the two tendencies proportional to the growth rate. In such a case, in order to avoid the confliction, the lamella structure will become metastable with an increase in α/γ interfacial energy and undercooling.

    Original languageEnglish
    Pages (from-to)482-489
    Number of pages8
    JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
    Volume60
    Issue number5
    Publication statusPublished - 1996

    Fingerprint

    eutectic alloys
    lamella
    Eutectics
    rods
    Microstructure
    tendencies
    Undercooling
    microstructure
    Interfacial energy
    Laue method
    Solidification
    Aspect ratio
    interfacial energy
    habits
    supercooling
    Direction compound
    eutectics
    aspect ratio
    derivation
    deviation

    Keywords

    • Directional solidification
    • Eutectic
    • Lamellar structure
    • Nickel-tungsten
    • Rod-structure

    ASJC Scopus subject areas

    • Metals and Alloys

    Cite this

    Rod-lamella transition in directionally solidified Ni-W eutectic alloy. / Yoshida, Makoto; Tsujimura, Takao; Tsukagoshi, Toru; Nakae, Hideo.

    In: Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals, Vol. 60, No. 5, 1996, p. 482-489.

    Research output: Contribution to journalArticle

    Yoshida, Makoto ; Tsujimura, Takao ; Tsukagoshi, Toru ; Nakae, Hideo. / Rod-lamella transition in directionally solidified Ni-W eutectic alloy. In: Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals. 1996 ; Vol. 60, No. 5. pp. 482-489.
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    abstract = "The mechanism of rod to lamella transition with increasing growth rate was studied. The relationship between γ phase 〈100〉 direction and the α-phase microstructure was examined using the back-reflection Laue method. The influence of growth rate on the transition was also estimated by increasing the rate in the middle of directional solidification. The experimental results revealed that both the growth rate and the deviation of γ 〈100〉 from the growth direction amplified the aspect ratio of the transverse α-phase microstructure. A mechanism of the transition was proposed and summed up as follows. At first, we assume that the following two control factors exist for the decision of the microstructure: (1) tendency to organize low energy habit planes. (2) eutectic second phase tends to grow perpendicular to the S/L interface (parallel to the growth direction). If no confliction between the two tendencies occurs at the S/L interface, a rod structure will be formed. However, when the derivation of γ 〈100〉 from the growth direction exists, the rod structure will induce the confliction between the two tendencies proportional to the growth rate. In such a case, in order to avoid the confliction, the lamella structure will become metastable with an increase in α/γ interfacial energy and undercooling.",
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