中國有色金屬學(xué)報(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 22 No. 10 October 2012 |
（1. Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China;
2. Ningbo Sub-academy of the National Weapons Science Research Academy, Ningbo 315103, China;
3. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China）
Abstract:TiAl alloys were produced by investment casting method combined with induction skull melting (ISM) technique. In situ scanning electron microscopy (SEM) was utilized to study the fracture characteristics and crack propagation of a notched investment cast TiAl specimens in tension under incremental loading conditions. The whole process of crack initiation, propagation and failure during tensile deformation was observed and characterized. The results show that the fracture mechanism was sensitive to not only the microcracks near the notched area but also lamellar orientation to loading axis. The high tensile stress leads to the new microcracks nucleate along lamellar interfaces of grains with favorable orientation when local stress intensity reaches the toughness threshold of the material. Thus, both plasticity and high tensile stress are required to cause notched TiAl failure.
Key words: TiAl alloys; investment cast; fracture characteristics; in situ SEM observation
