Unified interpretation of internal stress superplasticity models based on thermally-activated kinetics
- Inst. of Space and Astronautical Science, Kanagawa (Japan)
Three main theoretical models of internal stress superplasticity proposed by Greenwood and Johnson [Proc. R. Soc. A, 1965, 283, 403], Sherby et al. [Mater. Sci. Technol., 1985, 1, 925], and Sato and Kuribayashi [Acta metall. mater., 1993, 41, 1759] have been expanded to include the temperature dependence of the average strain rate. It is revealed that the constitutive equations of these models are equivalent regarding the thermally activated kinetics, and that the apparent activation energy of internal stress superplasticity is equal to l/n (where n is the stress exponent of isothermal power-law creep) times that of isothermal power-law creep. This theoretical prediction has been experimentally verified by the thermal cycling creep tests using the same temperature profiles with several equivalent temperatures in a Be particle-dispersed Al matrix composite. The obtained apparent activation energy was 22kJ/mol, which is approximately 1/7 times that of isothermal creep.
- OSTI ID:
- 345108
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 5 Vol. 47; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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