Creep mechanisms of fully-lamellar TiAl based upon interface sliding
Deformation mechanisms of fully lamellar TiAl with a refined microstructure ({gamma} lamellae: 100 {approximately} 300 nm thick, {alpha}{sub 2} lamellae: 10 {approximately} 50 nm thick) crept at 760 C have been investigated. As a result of a fine structure, the motion and multiplication of lattice dislocations within both {gamma} and {alpha}{sub 2} lamellae are limited at low creep stresses ({lt}400 MPa). Therefore, the glide and climb of lattice dislocations are insignificant to creep deformation. The cooperative motion of interfacial dislocations on {gamma}/{alpha}{sub 2} and {gamma}/{gamma} interfaces (i.e., interface sliding) is proposed to be the dominant deformation mechanism at low stresses. Lattice dislocations impinged on lamellar interfaces are found to be the major obstacles impeding the motion of interfacial dislocations. The number of impinged lattice dislocations increases as the applied stress increases and, subsequently, causes the pileup of interfacial dislocations along the interfaces. Accordingly, deformation twinning activated by the pileup of interfacial dislocations is proposed to be the dominant deformation mechanism at high stresses ({gt}400 MPa).
- Research Organization:
- Lawrence Livermore National Lab., CA (US)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 20001567
- Report Number(s):
- CONF-981104-; ISBN 1-55899-458-0; ISSN 1067-9995; TRN: US0000167
- Resource Relation:
- Conference: High-Temperature Ordered Intermetallic Alloys VIII, Materials Research Society Symposium Proceedings, Boston, MA (US), 11/30/1998--12/03/1998; Other Information: PBD: 1999; Related Information: In: High-temperature ordered intermetallic alloys VIII. Materials Research Society symposium proceedings: Volume 552, by George, E.P.; Mills, M.J.; Yamaguchi, Masaharu [eds.], [600] pages.
- Country of Publication:
- United States
- Language:
- English
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