Deformation twinning in single crystals of a D0{sub 19} compound with an off-stoichiometric composition (Ti-36.5at.%Al)

Journal Article · Mon Sep 20 04:00:00 EDT 2004 · Acta Materialia

DOI:https://doi.org/10.1016/j.actamat.2004.06.051· OSTI ID:20634779

Kishida, K ^[1]; Takahama, Y ^[2]; Inui, H ^[2]

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1. Materials Engineering Laboratory, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)
2. Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan)

The characteristics of deformation twinning in single crystals of a D0{sub 19} compound Ti{sub 3}Al with off-stoichiometric composition (Ti-36.5at.%Al) have been studied in detail by trace analysis and transmission electron microscopy. Deformation twinning is operative only at high temperatures above 1000 deg. C when the compression axis is parallel to and close to the hexagonal c-axis. All observed deformation twins are assigned to be of the type II and the twinning elements are determined as: K1:'{l_brace}2-bar 1210-bar 3{r_brace}',K2:{l_brace}202-bar 1-bar {r_brace},{eta}1:<51-bar 4-bar 6-bar >,{eta}2:'<1-bar 32-bar 2>',s=0.346. The critical resolved shear stress for the '{l_brace}2-bar 1210-bar 3{r_brace}' twin is estimated to be about 50 MPa at 1000 deg. C and it gradually decreases with increasing temperature. The possible atom movements by the deformation twinning are described and the reasons why twinning of this type occurs only under a limited condition (i.e., off-stoichiometric compositions, high temperatures and compression axis being close to the c-axis) are discussed in the light of the atom movements by the deformation twinning.

• OSTI ID: 20634779
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 16 Vol. 52; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM COMPOUNDS
COMPRESSION
DEFORMATION
MECHANICAL PROPERTIES
MONOCRYSTALS
PRESSURE RANGE MEGA PA 10-100
STOICHIOMETRY
TEMPERATURE RANGE 1000-4000 K
TITANIUM COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
TWINNING