Flow stress behavior of Al-Cu-Li-Zr alloy containing Sc during hot compression deformation

Abstract

The flow stress behavior of Al-3.5Cu-1.5Li-0.25(Sc+Zr) alloy during hot compression deformation was studied by isothermal compression test using Gleeble-1500 thermal-mechanical simulator. Compression tests were preformed in the temperature range of 653–773 K and in the strain rate range of 0.001–10 s⁻¹ up to a true plastic strain of 0.7. The results indicate that the flow stress of the alloy increases with increasing strain rate at a given temperature, and decreases with increasing temperature at a given imposed strain rate. The relationship between the flow stress and the strain rate and the temperature was derived by analyzing the experimental data. The flow stress is in a hyperbolic sine relationship with the strain rate, and in an Arrhenius relationship with the temperature, which imply that the process of plastic deformation at an elevated temperature for this material is thermally activated. The flow stress of the alloy during the elevated temperature deformation can be represented by a Zener-Hollomon parameter with the inclusion of the Arrhenius term. The values of n, α and A in the analytical expressions of flow stress σ are fitted to be 5.62, 0.019 MPa⁻¹ and 1.51×10¹⁶ s⁻¹, respectively. The hot deformation activation energy is 240.85 kJ/mol.