Dynamic Deformation Behavior of Powder Metallurgy 2195 Al-Li Alloy at High Strain Rate: Experimental and Simulation
摘要
This study investigates the dynamic deformation behavior of the 2195 Al-Li alloy produced through powder metallurgy (PM) at high strain rates ranging from 3000 s−1 to 9000 s−1, utilizing the split-Hopkinson pressure bar (SHPB). Finite element simulations, employing the modified Johnson–Cook constitutive model in ANSYS/LS-DYNA, closely align with experimental results at strain rates between 3000 s−1 and 7500 s−1. However, at a strain rate of 9000 s−1, the true flow stress is typically much greater than the simulation predicts. As strain rates increase, impact damage disperses, eliminating noticeable cracks even at 9000 s−1. Additionally, grains develop a distinct core–shell structure, characterized by fine-grained areas that are encircled by larger grains, which occurs through processes of grain rotation, refinement, and recrystallization. Moreover, T1 (Al2CuLi) phases experience fracture, shortening, and redissolution into the matrix. At 9000 s−1, the stress–strain curve exhibits a smooth profile with minimal fluctuations, indicating that the compressed sample does not show signs of adiabatic shear instability. This stability results from the competition between dynamic hardening attributed to the core–shell structure and dynamic softening caused by the redissolution of precipitated phases during deformation. This research offers a fresh viewpoint on high strain rate deformation behavior of PM Al alloys.