Title

Prediction of Crack Paths Based Upon Detailed Microstructure Characterization in a Neair-γ TiAl Alloy

Document Type

Conference Proceeding

Publication Date

12-1-2005

Keywords

Crack Propagation, Fracture, Microcrack, TiAl, Twinning

Abstract

Fracture in a duplex γ -TiAl alloy with equiaxed grains has been studied. The crack path in a notched Mode I crack growth specimen was analyzed using a combination of orientation imaging microscopy and selected angle channeling patterns (to obtain the true c-axis orientation in each grain). A phenomenological fracture propagation parameter incorporating the contributions from deformation twinning and ordinary dislocation systems has been developed that is capable of identifying boundaries that are likely to nucleate microcracks. This fracture propagation parameter was then used to analyze the existing crack path to identify why sharp turns in the crack path occurred. With this understanding, grain boundaries in the microstructure ahead of the crack tip were analyzed to predict the expected fracture path, and to compare it to the actual crack path. Based upon this parameter, criteria for crystal orientations and misorientations for high toughness microstructures are proposed.

Journal Title

Materials Damage Prognosis - Proceedings of a Symposium of the Materials Science and Technology 2004 Conference

First Page

307

Last Page

314

ISBN

0873395972, 9780873395977

First Department

Engineering

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