Microstructure evolution and spall behavior of 2024Al alloy under ramp wave loading

Abstract

Understanding the strain rate-dependent response of materials is essential for optimizing their design and predicting service life. In this study, both ramp wave loading (10⁴–10⁵ s⁻¹) and square wave loading (10⁶ s⁻¹) were achieved by controlling the projectile structure in plate impact experiments. This work particularly focuses on spall strength, precipitation behavior and damage evolution in 2024Al alloy under ramp wave loading. The results reveal that ramp loading mitigates thermal softening through gradual stress variation and reduces dislocation–atomic interactions due to its extended rise time. Compared with square wave loading, the continuous strain under ramp loading promotes vacancy generation, facilitating abnormal precipitation. These factors collectively contribute to enhanced spall strength. The spallation mechanism is dominated by dislocation–grain boundary interactions, with void nucleation and growth primarily occurring at grain boundaries. The formation of double spall surfaces is attributed to tensile stress concentrations generated by shock wave reflections at the initial spall surface. This study emphasizes the influence of shock waves on the structure and damage behavior of the 2024Al alloy.