Quantitative evaluation of crack bridging in fully lamellar Ti-48Al-2Cr-2Nb
- Univ. of California, Santa Barbara, CA (United States). Materials Dept.
- 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
Similar Records
Effect of elevated temperature exposure on cast gamma titanium aluminide (Ti-48Al-2Cr-2Nb)
Subboundary characterization and creep deformation in investment cast Ti-48Al-2Nb-2Cr