Mechanisms of fatigue crack growth in Ti-48Al at ambient and elevated temperature
- Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering
- Univ. of Texas, Arlington, TX (United States)
Gamma-based titanium aluminides are of practical interest due to their potential to replace nickel- and cobalt-based alloys in aeroengines. The results of a study of crack-tip deformation on the mechanisms of fatigue crack growth in a model powder metallurgy (P/M) gamma-based titanium aluminide intermetallic (Ti-48Al) are presented in this paper. Note that compositions are quoted in atomic % unless stated otherwise. Crack-tip deformation is shown to occur by a combination of deformation-induced twinning and conventional slip at room temperature, and conventional reversed plasticity/slip only at elevated temperature (700 C). Differences between crack-tip deformation mechanisms at room- and elevated-temperature are explained by crack-tip transmission electron microscopy (TEM) analysis. The potential effects of twin toughening are also quantified using optical interference measurements of twin process zones and micromechanical models. The implications of the different crack-tip deformation mechanisms for cyclic irreversibility are discussed for crack growth at room- and elevated-temperature. The results suggest that slower fatigue crack growth rates at elevated-temperature are due to differences in crack-tip deformation and closure mechanisms.
- OSTI ID:
- 237840
- Journal Information:
- Scripta Metallurgica et Materialia, Vol. 33, Issue 7; Other Information: PBD: 1 Oct 1995
- Country of Publication:
- United States
- Language:
- English
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