Dynamic recrystallization and post-deformation hardening in 2195 aluminum alloy

The mechanisms governing dynamic recrystallization and post-deformation hardening in 2195 aluminum alloy with a bimodal initial microstructure were systematically investigated. To more accurately capture the kinetics of incomplete recrystallization, a modified Beta-based model was proposed, addressing limitations inherent in the classical Avrami model. Microstructural observations revealed the coexistence of continuous and discontinuous dynamic recrystallization, regulated by the distribution and characteristics of second phases. Nanoprecipitates inhibited grain boundary migration, thereby suppressing recrystallization, while larger microparticles promoted nucleation via a particle-stimulated mechanism. The deformation conditions characterized by a lower Zener-Hollomon parameter (lnZ) led to a significant reduction in the nanoprecipitate volume fraction, which diminished Zener pinning and lowered the resistance to boundary migration, thereby facilitating recrystallization. Simultaneously, the increased critical particle size at lower lnZ weakened discontinuous recrystallization. A physically based constitutive model integrating grain boundary, solid solution, dislocation, and Orowan strengthening contributions was established and reliably predicted yield strength across a range of deformation conditions. Notably, a post-deformation hardening effect was observed following hot deformation, despite preceding dynamic softening. This was attributed to residual strain energy accelerating natural aging, resulting in a divergence between hardness and yield strength. These results highlight the critical role of thermomechanical history in shaping the microstructural evolution and mechanical response of high-strength aluminum alloys.