Dynamic Mechanical Behavior and Microplastic Deformation Mechanism of AM50A Magnesium Alloy under High-Speed Impact
摘要
Magnesium alloys are lightweight metallic structural materials that are commonly used in large-scale applications in the aerospace, automotive, and electronic industries. These alloys often experience impact loads during service. Owing to the extremely short duration of the high-speed impact, the mechanical response of the material is delayed, resulting in significant differences in the material deformation mechanism compared with static and quasi-static loading conditions. In this study, we investigated the high-speed impact behavior of the AM50A magnesium alloy using a split Hopkinson pressure bar experiment device. The dynamic mechanical response of the AM50A magnesium alloy was systematically examined in both the radial and axial directions at different strain rates, to analyze the effect of the strain rate on the dynamic stress-strain behavior. Transmission electron microscopy was employed to observe the dislocation morphology of AM50A under varying experimental conditions and deformation stages, revealing the microdynamic deformations under high-speed impacts and the influence of the stress-strain rate. Additionally, an electron backscatter diffraction analysis was conducted to study the grain orientation and microstructural evolution of the AM50A magnesium alloy during high-strain-rate compressive deformation at strain rates ranging from 1000 to 3000 s-1. We believe that this study will enhance the understanding of the high-speed plastic deformation and failure mechanisms of AM50A magnesium alloys, providing a theoretical foundation for optimizing high-speed large-deformation rolling, high-speed extrusion, and cutting process control in magnesium alloy applications.