Abstract
The deformation behavior of a 0.2% Zr and 1.6% Mn modified 5083 aluminum alloy was studied in the temperature range of 250–570 ◦C
over seven orders of magnitude of strain rates. It was shown that the modified 5083 alloy exhibits threshold behavior in the temperature interval
of 250–500 ◦C. There exists a temperature dependence of threshold stress with the energy term Qo = 18 kJ/mol. It was shown by transmission
election microscopy that detachment of dislocations from dispersoids under extra force takes place. Threshold stress tends to disappear with
increasing temperature at T > 500 ◦C despite the fact that evidence for interactions between mobile dislocations and dispersoids was found at
these temperatures. Analysis of creep data in terms of threshold stress revealed three different types of deformation behavior. At high values
of normalized strain rate, ˙εkT/(D1Gb) > 4 × 10−8, the exponential law creep takes place. At normalized strain rates, ˙εkT/(D1Gb), ranging
from 4×10−8 to 4×10−14, the n value is ∼4 and the true activation energy, Qc, is equal to 139±12 kJ/mol, suggesting high temperature
dislocation climb. At low normalized strain rate, a transition to Newtonian viscous flow occurs.
© 2004 Elsevier B.V. All rights reserved