High-temperature deformation processing of Ti-24Al-20Nb
- Defence Metallurgical Research Lab., Hyderabad (India)
- Indian Inst. of Science, Bangalore (India). Dept. of Metallurgy
Power dissipation maps have been generated in the temperature range of 900 C to 1,150 C and strain rate range of 10{sup {minus}3} to 10 s{sup {minus}1} for a cast aluminide alloy Ti-24Al-20Nb using dynamic material model. The results define two distinct regimes of temperature and strain rate in which efficiency of power dissipation is maximum. The first region, centered around 975 C/0.1 s{sup {minus}1}, is shown to correspond to dynamic recrystallization of the {alpha}{sub 2} phase and the second, centered around 1,150 C/0.001 s{sup {minus}1}, corresponds to dynamic recovery and superplastic deformation of the {beta} phase. Thermal activation analysis using the power law creep equation yielded apparent activation energies of 854 and 627 kJ/mol for the first and second regimes, respectively. Reanalyzing the data by alternate methods yielded activation energies in the range of 170 to 220 kJ/mol and 220 to 270 kJ/mol for the first and second regimes, respectively. Cross slip was shown to constitute the activation barrier in both cases. Two distinct regimes of processing instability--one at high strain rates and the other at the low strain rates in the lower temperature regions--have been identified, within which shear bands are formed.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 382511
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 27, Issue 9; Other Information: PBD: Sep 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mechanical and microstructural response of Ti-24Al-11Nb as a function of temperature and strain rate
Characteristics of the Hot Workability of an AZ91D Magnesium Alloy Using 3D Processing Maps