skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Creep mechanisms and interface-enhanced deformation twinning in a two-phase lamellar TiAl alloy

Abstract

Deformation mechanisms and the role of interfaces in deformation twinning of a two-phase [TiAl({gamma})/Ti{sub 3}Al({alpha}{sub 2})] lamellar alloy creep deformed at elevated temperatures have been investigated. Since the multiplication of lattice dislocations within both {gamma} and {alpha}{sub 2} lamellae is very limited at a low stress level due to a refined lamellar microstructure, the glide of interfacial dislocations on both {gamma}/{alpha}{sub 2} and {gamma}/{gamma} interfaces (i.e interface sliding) becomes an important deformation mode. Obstacles such as impinged lattice dislocations can impede the movement of interfacial dislocations, which glide in a cooperative fashion along the lamellar interfaces. The impediment of dislocation motion subsequently causes a dislocation pile-up in front of obstacles as creep strain accumulates. When the crystals deform at high stress level, deformation twinning becomes a predominant deformation mode. Deformation twins are found to nucleate from the interfaces as a result of a local stress concentration generated from dislocation pile-ups. It is suggested that the deformation twinning in lamellar TiAl/Ti{sub 3}Al crystals can be vieived as a stress relaxation process for the concentration of stress at the head of each dislocation pile-up. An interface-assisted twinning mechanism is accordingly proposed and discussed.

Authors:
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
289275
Report Number(s):
UCRL-JC-130082; CONF-980716-
ON: DE98058773; BR: KC0201050
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: 3. Pacific Rim international conference on advanced materials and processing, Honolulu, HI (United States), 12-16 Jul 1998; Other Information: PBD: 1 Mar 1997
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; TITANIUM ALLOYS; ALUMINIUM ALLOYS; INTERFACES; CREEP; TWINNING; DEFORMATION; DISLOCATIONS; MICROSTRUCTURE

Citation Formats

Hsiung, L.M., LLNL. Creep mechanisms and interface-enhanced deformation twinning in a two-phase lamellar TiAl alloy. United States: N. p., 1997. Web.
Hsiung, L.M., LLNL. Creep mechanisms and interface-enhanced deformation twinning in a two-phase lamellar TiAl alloy. United States.
Hsiung, L.M., LLNL. 1997. "Creep mechanisms and interface-enhanced deformation twinning in a two-phase lamellar TiAl alloy". United States. https://www.osti.gov/servlets/purl/289275.
@article{osti_289275,
title = {Creep mechanisms and interface-enhanced deformation twinning in a two-phase lamellar TiAl alloy},
author = {Hsiung, L.M., LLNL},
abstractNote = {Deformation mechanisms and the role of interfaces in deformation twinning of a two-phase [TiAl({gamma})/Ti{sub 3}Al({alpha}{sub 2})] lamellar alloy creep deformed at elevated temperatures have been investigated. Since the multiplication of lattice dislocations within both {gamma} and {alpha}{sub 2} lamellae is very limited at a low stress level due to a refined lamellar microstructure, the glide of interfacial dislocations on both {gamma}/{alpha}{sub 2} and {gamma}/{gamma} interfaces (i.e interface sliding) becomes an important deformation mode. Obstacles such as impinged lattice dislocations can impede the movement of interfacial dislocations, which glide in a cooperative fashion along the lamellar interfaces. The impediment of dislocation motion subsequently causes a dislocation pile-up in front of obstacles as creep strain accumulates. When the crystals deform at high stress level, deformation twinning becomes a predominant deformation mode. Deformation twins are found to nucleate from the interfaces as a result of a local stress concentration generated from dislocation pile-ups. It is suggested that the deformation twinning in lamellar TiAl/Ti{sub 3}Al crystals can be vieived as a stress relaxation process for the concentration of stress at the head of each dislocation pile-up. An interface-assisted twinning mechanism is accordingly proposed and discussed.},
doi = {},
url = {https://www.osti.gov/biblio/289275}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1997},
month = {3}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share: