High-temperature deformation processing of Ti-24Al-20Nb

Sagar, P. K. ; Banerjee, D. ; Muraleedharan, K. ; Prasad, Y. V. R. K. (1996) High-temperature deformation processing of Ti-24Al-20Nb Metallurgical and Materials Transactions A, 27A (9). pp. 2593-2604. ISSN 1073-5623

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Official URL: http://www.springerlink.com/content/m13616475l431h...

Related URL: http://dx.doi.org/10.1007/BF02652353


Power dissipation maps have been generated in the temperature range of 900°C to 1150°C and strain rate range of 10-3 to 10 s-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-1, is shown to correspond to dynamic recrystallization of the α2 phase and the second, centered around 1150°C/0.001 s-1, corresponds to dynamic recovery and superplastic deformation of the β 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.

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Source:Copyright of this article belongs to The Minerals, Metals & Materials Society.
ID Code:37351
Deposited On:30 Apr 2011 08:03
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