Microstructural characterisation of fatigue crack growth fracture surfaces of lamellar Ti45Al2Mn2Nb1B

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Abstract

Investment cast Ti45Al2Mn2Nb1B with fine lamellar microstructures was subject to fatigue crack propagation testing at 650 °C and a stress ratio of R = 0.1. The fracture surfaces were examined under SEM and the observed features are correlated with both stress intensity range (ΔK) and lamellar orientation. Translamellar fracture is primary fracture mode for most of the lamellar orientations. Interlamellar fracture is influenced by a combination of the ΔK and lamellar orientation. At low ΔK only the lamellar colonies with their lamellar interfaces almost perpendicular to the stress axis fractured via interlamellar fracture mode. At high ΔK interlamellar fracture can occur in lamellar colonies with any orientations.

Details

Original languageEnglish
Pages (from-to)89-95
JournalIntermetallics
Volume45
Early online date2 Nov 2013
Publication statusPublished - 1 Feb 2014

Keywords

  • A. Titanium aluminides, based on TiAl, B. Fatigue resistance and crack growth, B. Fracture mode, D. Microstructure (as-cast)