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Title: Role of interfacial dislocations on creep of a fully lamellar tial

Abstract

Deformation mechanisms of a fully lamellar TiAl ({gamma} lamellae: 100 {approximately} 300 nm thick, {alpha}{sub 2} lamellae: 10 {approximately} 50 nm thick) crept at 760 C have been investigated. It was found that, as a result of a fine structure, the motion and multiplication of dislocations within both {gamma} and {alpha}{sub 2} lamellae are limited at low creep stresses (< 400 MPa). Thus, the glide and climb of lattice dislocations have insignificant contribution to creep deformation. In contrast, the motion of interfacial dislocations on {gamma}{alpha}{sub 2} and {gamma}{gamma} interfaces (i.e. interface sliding) dominates the deformation at low stresses. The major obstacles impeding the motion of interfacial dislocations was found to be lattice dislocations impinging on lamellar interfaces. The number of impinging lattice dislocations increases as the applied stress increases and, subsequently, causes the pileup of interfacial dislocations on the interfaces. The pileup further leads to the formation of deformation twins. Deformation twinning activated by the pileup of interfacial dislocations is suggested to be the dominant deformation mechanism at high stresses (> 400 MPa).

Authors:
;
Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA (US)
Sponsoring Org.:
USDOE Office of Defense Programs (DP) (US)
OSTI Identifier:
12553
Report Number(s):
UCRL-JC-135382; KC0201050
KC0201050; TRN: AH200120%%354
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: The 8th International Conference on Creep and Fracture of Engineering Materials and Structures, Tsukuba (JP), 11/01/1999--11/05/1999; Other Information: PBD: 16 Aug 1999
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CREEP; DEFORMATION; DISLOCATIONS; FINE STRUCTURE; FRACTURES; LAMELLAE; STRESSES; TWINNING

Citation Formats

Hsiung, L M, and Nieh, T G. Role of interfacial dislocations on creep of a fully lamellar tial. United States: N. p., 1999. Web.
Hsiung, L M, & Nieh, T G. Role of interfacial dislocations on creep of a fully lamellar tial. United States.
Hsiung, L M, and Nieh, T G. Mon . "Role of interfacial dislocations on creep of a fully lamellar tial". United States. https://www.osti.gov/servlets/purl/12553.
@article{osti_12553,
title = {Role of interfacial dislocations on creep of a fully lamellar tial},
author = {Hsiung, L M and Nieh, T G},
abstractNote = {Deformation mechanisms of a fully lamellar TiAl ({gamma} lamellae: 100 {approximately} 300 nm thick, {alpha}{sub 2} lamellae: 10 {approximately} 50 nm thick) crept at 760 C have been investigated. It was found that, as a result of a fine structure, the motion and multiplication of dislocations within both {gamma} and {alpha}{sub 2} lamellae are limited at low creep stresses (< 400 MPa). Thus, the glide and climb of lattice dislocations have insignificant contribution to creep deformation. In contrast, the motion of interfacial dislocations on {gamma}{alpha}{sub 2} and {gamma}{gamma} interfaces (i.e. interface sliding) dominates the deformation at low stresses. The major obstacles impeding the motion of interfacial dislocations was found to be lattice dislocations impinging on lamellar interfaces. The number of impinging lattice dislocations increases as the applied stress increases and, subsequently, causes the pileup of interfacial dislocations on the interfaces. The pileup further leads to the formation of deformation twins. Deformation twinning activated by the pileup of interfacial dislocations is suggested to be the dominant deformation mechanism at high stresses (> 400 MPa).},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1999},
month = {8}
}

Conference:
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