The role of twinning in brittle fracture of Ti-aluminides

Conference · Mon Jan 01 00:00:00 EST 1990

OSTI ID:6152611

Yoo, M H; Fu, C L; Lee, J K

The important roles of (111)(11{bar 2}) twinning in cleavage fracture of single phase {gamma}-TiAl and TiAl{sub 3} are assessed on the basis of theoretically calculated elastic constants, shear fault energies, and cleavage energies. The importance of elastic anisotropy in both homogeneous twin nucleation theory and dislocation models for twin nucleation is emphasized. The twin-slip conjugate relationship makes an important contribution to the strain compatibility for localized plasticity at crack-tip of Mode-I type. The intrinsic brittleness of these aluminides is attributed to a combined effect of the low mobility of slip and twin dislocations and the relatively low cleavage strength. Effect of the resolved normal stress on the twin plane is to enhance twinning activity at a (110) crack-tip, leading to transformation toughening of shear type. 28 refs., 8 figs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6152611
• Report Number(s): CONF-901105-48; ON: DE91005506
• Resource Relation: Conference: Fall meeting of the Materials Research Society, Boston, MA (USA), 24 Nov - 1 Dec 1990
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
TWINNING
TITANIUM ALLOYS
BRITTLENESS
CRYSTAL STRUCTURE
DEFORMATION
DISLOCATIONS
FRACTURES
INTERMETALLIC COMPOUNDS
MECHANICAL PROPERTIES
ALLOYS
CRYSTAL DEFECTS
FAILURES
LINE DEFECTS
360102* - Metals & Alloys- Structure & Phase Studies
360103 - Metals & Alloys- Mechanical Properties