Fracture and fracture toughness of directionally solidified TiAl-based two-phase alloys
- Kyoto Univ., Sakyo (Japan). Dept. of Materials Science and Engineering
The TiAl({gamma})/Ti{sub 3}Al({alpha}{sub 2}) lamellar microstructure in {gamma}-based two-phase alloys are of special interest since {gamma}-based alloys having a fully lamellar microstructure exhibit good creep and fracture resistance at temperatures up to 800 C. The authors have introduced a new approach for studying the {gamma}/{alpha}{sub 2} lamellar microstructure by producing polysynthetically twinned (PST) crystals with the lamellar microstructure derived from a single {alpha} grain and thus with the same lamellar orientation over the entire crystal by means of directional solidification techniques. The authors have been working on the deformation behavior of such PST crystals to understand the mechanical properties of the lamellar microstructure in {gamma}-based two-phase alloys at a fundamental level. Recently, they have extended the study of mechanical properties of PST crystals to directionally solidified ingots composed of columnar grains with the lamellar structure aligned parallel to the growth direction. In this paper, the fracture behavior, fracture surface morphology and fracture toughness of PST crystals and directionally solidified ingots are discussed as a function of lamellar orientation, test environment, loading rate and alloy composition.
- OSTI ID:
- 293140
- Report Number(s):
- CONF-970980--; ISBN 0-87339-381-3
- Country of Publication:
- United States
- Language:
- English
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