Quantitative evaluation of crack bridging in fully lamellar Ti-48Al-2Cr-2Nb

Book · Tue Aug 01 04:00:00 EDT 1995

OSTI ID:78363

Wissuchek, D J; Lucas, G E ^[1]; Evans, A G ^[2]

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1. Univ. of California, Santa Barbara, CA (United States). Materials Dept.
2. Harvard Univ., Cambridge, MA (United States). Division of Applied Sciences

The toughening effect of ligaments in a fully lamellar Ti-48Al-2Cr-2Nb alloy has been determined by evaluation of J integrals of the crack tip and crack wake regions from surface strain maps. The crack tip fracture toughness K{sub tip} was found to vary with lamellae orientation and ranged from K{sub tip} = 13 MPa{radical}m for inter-lamellar fracture to K{sub tip} = 19.5 MPa{radical}m for translamellar fracture. The bridging contribution to fracture toughness was found to arise from a bimodal distribution of ligament sizes. Fracture surface reconstructions showed a distribution of large hinges that initiated at grain or subcolony boundaries and smaller ligaments associated with delaminations within a grain. The stress-displacement functions for these two ligament populations have been determined from a large scale bridging analysis of the resistance curves along with fractographic information. The small ligaments appear to account for the initial rapid rise in crack growth resistance; and the large hinges, for the slow continued rise in toughness at large crack extensions.

• OSTI ID: 78363
• Report Number(s): CONF-941144--; ISBN 1-55899-265-0
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
CRACK PROPAGATION
EXPERIMENTAL DATA
FRACTURE PROPERTIES
INTERMETALLIC COMPOUNDS
MICROSTRUCTURE
NIOBIUM ALLOYS
TITANIUM ALLOYS