Effects of TiN nanoparticles on hot deformation behavior of ultra-fine grained Al2024-TiN nanocomposites prepared by spark plasma sintering

Abstract

In this study, hot compression tests of ultra-fine grained Al2024 alloy and Al2024-TiN nanocomposite were performed at 350–500 °C temperature and 0.01–10 s−1 strain rate on a Gleeble-3500 thermal mechanical simulator. The results show that stress increases as strain rate increases and temperature decreases in both materials. The strengthening effect of TiN appeared to be weaker than the softening effect of ultra-fine grains during hot deformation. Al2024-TiN presented lower stable flow stress than Al2024 under the same deformation conditions. Constitutive equations and processing maps were established based on the flow stress curves. The deformation activation energies of Al2024 and Al2024-TiN were determined to be 239.260 and 749.386 kJ•mol−1, respectively. The optimum deformation area of the Al2024-TiN nanocomposite has a lower temperature and higher strain rate than that of the Al2024 alloy. Microstructural analysis revealed that TiN nanoparticles restrain grain growth and promote dynamic recrystallization during hot deformation. The deformation mechanism of Al2024-TiN was found to be grain boundary sliding accompanied with dynamic recrystallization, dynamic recovery, and grain growth, that of Al2024 is intra-granular sliding accompanied with dynamic recovery and grain growth. This work may provide a workable set of guidelines to optimize the hot deformation process of ultra-fine grained Al2024-TiN nanocomposites and other similar materials.