Thermal deformation behavior and microstructural evolution of the rapidly-solidified Al–Zn–Mg–Cu alloy in hot isostatic pressing state

Abstract

Isothermal uniaxial compression experiments were performed in the temperature range of 340–460 °C and the deformation rate range of 0.001–1 s−1 to analyze the hot deformation behavior of the rapidly-solidified Al–Zn–Mg–Cu alloy in hot isostatic pressing state. A strain-compensated constitutive model was established to determine the flow stress in the alloy (based on the true stress-true strain data), and the average activation energy for the hot deformation was calculated as Q = ∼146 kJ/mol. The proposed model exhibited a high predictability with an average absolute relative error of 2.68% and a correlation coefficient of 0.99724. The processing map revealed that the alloy in the hot isostatic pressed state offers better workability than the spray-deposited alloy, and its optimal workable ranges at a strain of 0.78 are 370–390 °C/0.004–0.01 s−1 and 400–460 °C/0.005–0.06 s−1, respectively. The microstructural evolution shows that the main dynamic softening mechanism changes from dynamic recovery to continuous dynamic recrystallization with the increase in temperature and the decrease in strain rate.

Keywords

• Al–Zn–Mg–Cu alloy
• Hot isostatic pressing
• Constitutive model
• Processing map
• Microstructure evolution