Investigations on the microstructure and room temperature fracture toughness of directionally solidified NiAl–Cr(Mo) eutectic alloy |
| |
| Affiliation: | 1. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China;2. National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin, 150001, China;3. Institute of High Pressure Fluid Forming Technology, Harbin Institute of Technology, Harbin, 150001, China;1. Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz, 6135743337, Iran;2. Department Physics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, 6135743337, Iran;1. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China;2. National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001, China |
| |
| Abstract: | The microstructures and room temperature fracture toughness of directionally solidified NiAl-xCr-6Mo (x = 28, 32 and 36 at%) alloys were investigated. Fully eutectic microstructure could be obtained in the alloys over a wide composition range. High temperature gradient could increase the planar/cellular transition rate and expand the eutectic coupled growth zone. The volume fraction of Cr(Mo) strengthening phase increased with the increasing content of Cr, accordingly, the fracture toughness of NiAl–Cr(Mo) alloys also gradually increased. The fracture toughness of 26.15 MPa m1/2 was obtained in the NiAl-36Cr-6Mo hypereutectic alloy solidified at withdrawal rate of 10 μm/s and temperature gradient of 600 K/cm, which is the highest value in the NiAl–Cr–Mo alloy system until now. Well-aligned microstructure was beneficial to the enhancement of the fracture toughness, while the existence of primary phase seriously deteriorated the toughness. All the directionally solidified NiAl–Cr(Mo) alloy failed as brittle quasi-cleavage fracture. Some toughening mechanisms, such as crack bridging, crack nucleation, crack blunting, crack deflection, interface debonding and shear ligament toughening as well as linkage of microcracks were observed. In addition, mobile dislocation generated from the interface also had significant influence on the toughness. |
| |
| Keywords: | A Nickel aluminides based on NiAl B Crack propagation B Fracture toughness C Crystal growth D Microstructure G Aero-engine components |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
