Compressive properties and failure mechanisms of AlON ceramics under different strain rates

The static and dynamic compressive properties of AlON ceramics were investigated using a universal testing machine and a split Hopkinson pressure bar (SHPB) device. The test results indicated that AlON ceramics exhibit nearly identical compressive strength under quasi-static loading. However, a significant strain rate strengthening effect was observed under dynamic loading. Elongated fragments were obtained when the specimens were subjected to quasi-static loading, while the fragments were finely granular for the specimens exposed to dynamic loading. During the compression of AlON ceramics, the pre-existing twins substantially impeded crack propagation and dislocation motion, and the fracture surfaces not only display conventional intergranular and transgranular fractures but also include the characteristics of secondary cracks, fragmented regions, dislocation networks, dislocation arrays, and even subgrain boundaries. Multiple dislocation motion modes and the formation of subgrain boundaries indicated a plastic behavior of AlON ceramics under high-strain-rate dynamic loading. AlON ceramics exhibit the complexity of dislocation behavior in response to impact force.