Superb impact resistance of nano-precipitation-strengthened high-entropy alloys

Critical engineering applications, such as landing gears and armor protection, require structural materials withstanding high strength and significant plastic deformation. Nanoprecipitate-strengthened high-entropy alloys (HEAs) are considered as promising candidates for structural applications due to their enhanced strength and exceptional work-hardening capability. Herein, we report a FeCoNiAlTi-type HEA that achieves ultrahigh gigapascal yield strength from quasi-static to dynamic loading conditions and superb resistance to adiabatic shear failure. This is accomplished by introducing high-density coherent L1 2 nanoprecipitates. Multiscale characterization and molecular dynamics simulation demonstrate that the L1 2 nanoprecipitates exhibit multiple functions during impact, not only as the dislocation barrier and the dislocation transmission medium, but also as energy-absorbing islands that disperse the stress spikes through order-to-disorder transition, which result in extraordinary impact resistance. These findings shed light on the development of novel impact-resistant metallic materials. By introducing high-density coherent L1 2 nanoprecipitates, the FeCoNiAlTi-type HEA achieves high quasi-static/dynamic mechanical properties. The hierarchical deformation mechanism provides various pathways for dissipating the impact strain energy, thereby endowing the HEA with extremely high impact resistance.