Superplastic behavior of TiAl based alloy with rapidly hot-deformed microstructure at low temperatures
Superplastic behavior of a Ti-33Al-3Cr (wt %) alloy with homogeneous and fine hot-deformed microstructure was studied using the uniaxial tension test in air in the temperature range of 800 C to 1,075 C and in the strain-rate range of 1 x 10{sup {minus}5} s{sup {minus}1} to 3 x 10{sup {minus}3} s{sup {minus}1}. Test results showed that the material had a great capacity of superplastic deformation. The percentage elongation was 410% at the temperature of 850 C and at the strain rate of 2 x 10{sup {minus}4} s{sup {minus}1}. The maximum percentage elongation, 520%, was obtained, when the temperature increased to 1075 C, and at the strain rate of 8 x 10{sup {minus}5} s{sup {minus}1}. Even when the temperature decreased to 800 C, the percentage elongation was 280% at the strain rate of 2 x 10{sup {minus}4} s{sup {minus}1}. The strain-rate sensitivity coefficient was measured by the incremental strain-rate technique. It was found that the strain-rate sensitivity coefficient reached its maximum value at 900 C--1,075 C with a strain rate of 3 x 10{sup {minus}5} s{sup {minus}1}. Furthermore, it changed insignificantly during the superplastic deformation, indicating that the material had a very high stability of superplastic deformation, indicating that the material had a very high stability of superplastic deformation. That is very important for the application of the superplasticity technique used to produce the TiAl based alloy parts. The mechanisms of superplastic deformation are different at various temperatures for the hot-deformed TiAl based alloy. The grain-boundary sliding governs the superplastic deformation at 900 C, and the dynamic recrystallization controls the superplastic deformation at 1025 C from the approach of microstructural evolutions and the sensitivity of stress on the strain.
- Research Organization:
- Univ. of Tennessee, Knoxville, TN (US)
- OSTI ID:
- 20014199
- Country of Publication:
- United States
- Language:
- English
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