In-situ TEM study of fracture mechanisms of polysynthetically twinned (PST) crystals of TiAl alloys

Authors
Lu, YH Zhang, YG Qiao, LJ Wang, YB Chen, CQ Chu, WY
Citation
Yh. Lu et al., In-situ TEM study of fracture mechanisms of polysynthetically twinned (PST) crystals of TiAl alloys, MAT SCI E A, 289(1-2), 2000, pp. 91-98
Citations number
20
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
ISSN journal
09215093 → ACNP
Volume
289
Issue
1-2
Year of publication
2000
Pages
91 - 98
Database
ISI
SICI code
0921-5093(20000930)289:1-2<91:ITSOFM>2.0.ZU;2-X
Abstract
The fracture mechanisms of polysynthetically twinned (PST) crystals of Ti-4 9at.% Al in different lamellar orientations have been investigated by using in-situ transmission electron microscopy (TEM). The results indicated that the fracture mechanisms and crack propagation behavior depended strongly o n the lamellar orientation of PST crystals. When the tensile axis was nearl y parallel to the lamellae, the main crack propagated discontinuously by nu cleation, growth and linkage of microcracks formed ahead of crack tip. Slip band decohesion, fracture along prism plane of alpha(2) plates and twinnin g-induced microcracks are three modes of nucleation of microcracks. When th e loading axis was perpendicular to the lamellae, the crack parallel to the lamellae propagated by tearing and shear of shear ligament. Interfacial mi crocrack usually occurred ahead of the main crack tip. Sometimes, the main crack propagated along (111) cleavage plane within gamma lamellae. (C) 2000 Elsevier Science S.A. All rights reserved.