In situ observations of the deformation behavior and fracture mechanisms of Ti-45Al-2Nb-2Mn + 0.8 vol pct TiB 2

Rocio Muñoz-Moreno, Carl J. Boehlert, M. Teresa Pérez-Prado, Elisa M. Ruiz-Navas, Javier Llorca

    Research output: Research - peer-reviewArticle

    • 12 Citations

    Abstract

    The deformation and fracture mechanisms of a nearly lamellar Ti-45Al-2Nb-2Mn (at. pct) + 0.8 vol pct TiB 2 intermetallic, processed into an actual low-pressure turbine blade, were examined by means of in situ tensile and tensile-creep experiments performed inside a scanning electron microscope (SEM). Low elongation-to-failure and brittle fracture were observed at room temperature, while the larger elongations-to-failure at high temperature facilitated the observation of the onset and propagation of damage. It was found that the dominant damage mechanisms at high temperature depended on the applied stress level. Interlamellar cracking was observed only above 390 MPa, which suggests that there is a threshold below which this mechanism is inhibited. Failure during creep tests at 250 MPa was controlled by intercolony cracking. The in situ observations demonstrated that the colony boundaries are damage nucleation and propagation sites during tensile creep, and they seem to be the weakest link in the microstructure for the tertiary creep stage. Therefore, it is proposed that interlamellar areas are critical zones for fracture at higher stresses, whereas lower stress, high-temperature creep conditions lead to intercolony cracking and fracture.

    LanguageEnglish (US)
    Pages1198-1208
    Number of pages11
    JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
    Volume43
    Issue number4
    DOIs
    StatePublished - Apr 2012

    Profile

    Creep
    Temperature
    damage
    tensile creep
    elongation
    propagation
    Elongation
    creep tests
    turbine blades
    intermetallics
    low pressure
    electron microscopes
    nucleation
    microstructure
    scanning
    thresholds
    room temperature
    Brittle fracture
    Turbomachine blades
    Intermetallics

    ASJC Scopus subject areas

    • Condensed Matter Physics
    • Metals and Alloys
    • Mechanics of Materials

    Cite this

    In situ observations of the deformation behavior and fracture mechanisms of Ti-45Al-2Nb-2Mn + 0.8 vol pct TiB 2 . / Muñoz-Moreno, Rocio; Boehlert, Carl J.; Teresa Pérez-Prado, M.; Ruiz-Navas, Elisa M.; Llorca, Javier.

    In: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, Vol. 43, No. 4, 04.2012, p. 1198-1208.

    Research output: Research - peer-reviewArticle

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    abstract = "The deformation and fracture mechanisms of a nearly lamellar Ti-45Al-2Nb-2Mn (at. pct) + 0.8 vol pct TiB 2 intermetallic, processed into an actual low-pressure turbine blade, were examined by means of in situ tensile and tensile-creep experiments performed inside a scanning electron microscope (SEM). Low elongation-to-failure and brittle fracture were observed at room temperature, while the larger elongations-to-failure at high temperature facilitated the observation of the onset and propagation of damage. It was found that the dominant damage mechanisms at high temperature depended on the applied stress level. Interlamellar cracking was observed only above 390 MPa, which suggests that there is a threshold below which this mechanism is inhibited. Failure during creep tests at 250 MPa was controlled by intercolony cracking. The in situ observations demonstrated that the colony boundaries are damage nucleation and propagation sites during tensile creep, and they seem to be the weakest link in the microstructure for the tertiary creep stage. Therefore, it is proposed that interlamellar areas are critical zones for fracture at higher stresses, whereas lower stress, high-temperature creep conditions lead to intercolony cracking and fracture.",
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    AU - Ruiz-Navas,Elisa M.

    AU - Llorca,Javier

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