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: Contribution to journalArticle

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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.

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
tensile creep
damage
elongation
Elongation
creep tests
turbine blades
propagation
Temperature
intermetallics
Brittle fracture
low pressure
electron microscopes
Turbomachine blades
Intermetallics
nucleation
Turbines
Nucleation
Electron microscopes
microstructure

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: Contribution to journalArticle

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