Microstructural evolution and mechanical properties of forged β-solidified γ-TiAl alloy by different heat treatments
(1. Ji Hua Laboratory (Advanced Manufacturing Science and Technology Guangdong Laboratory), Foshan 528200, China;
2. MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, Nanjing University of Science and Technology, Nanjing 210094, China;
3. Shi-changxu Innovation Center for Advanced Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
2. MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, Nanjing University of Science and Technology, Nanjing 210094, China;
3. Shi-changxu Innovation Center for Advanced Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
Abstract: The microstructural evolution and tensile properties of a forged Ti-42Al-5Mn alloy subjected to different heat treatments were studied. The results showed that, when the forged alloy was aged at 800 °C for 24 h, the interlamellar spacing (λ) and γ grain size at colony boundaries are generally coarsened. Whereas, when the alloy was first annealed at 1300 °C and then aged at 800 °C for 24 h, this coarsening of related microstructures appears less pronounced. The suggested annealing temperatures for the forged Ti-42Al-5Mn alloy are in the range of 1250-1300 °C. It was found that, on the condition of the same annealing system, both the strength and ductility were improved as the aging temperature changed from 1000 to 800 °C. The secondary precipitated βo (βo,sec) at colony boundaries could be responsible for improving the strength, and the γ phase at colony boundaries with the grain size about 6 μm might be one of the main reasons for the better ductility.
Key words: β-solidifying γ-TiAl alloy; forge; heat treatment; microstructural evolution; mechanical properties