Influence of columnar grain boundary on fracture behavior of as-cast fully lamellar Ti-46Al-0.5W-0.5Si alloy

• Published in: China foundry 2012-02, Vol.9 (1), p.64-68
• Main Authors: Chen, Hui, Su, Yanqing, Luo, Liangshun, Li, Xinzhong, Liu, Jiangping, Guo, Jingjie, Fu, Hengzhi
• Format: Article
• Language: English
• Subjects: Boundaries; Crack initiation; Crack propagation; fracture behavior; Fracture mechanics; full lamellar; Grain boundaries; grain boundary; Orientation; Running; Titanium base alloys; γ-TiAl alloy
• ISSN: 1672-6421; 2365-9459

The fracture behavior of fully lamellar γ-TiAl alloys depends on the angle between the lamellar orientation and loading axis, but the role of the presentation of grain boundary cannot be ignored. To investigate the influence of the grain boundary on the initiation and propagation of cracks, the tensile test of the alloy was conducted at room temperature with loading axis parallel and perpendicular to the lamellar orientation, respectively. The cracks adjacent to the fracture zone of the tensile specimens have been investigated to analyze the fracture behavior. Results show that the grain boundary has dual influences on the fracture behavior. When the loading axis is parallel to the lamellar orientation, cracks are preferentially initiated at and propagate along the grain boundaries. When the loading axis is perpendicular to the lamellar orientation, the grain boundaries can prevent the propagation of cracks from running across. Additionally, serrated-shape grain boundaries have a better inhibiting effect on the propagation of cracks than planar boundaries.