Microstructure and nanohardness distribution in a polycrystalline Zn deformed by high strain rate impact

► A polycrystalline Zn specimen was submitted to high strain rate impact loading. ► Inhomogeneous grain refinement occurred due to strain gradient in impacted sample. ► A fine-grained recrystallized rim surrounded the coarse-grained center of specimen. ► The coarse-grained center exhibited higher hardness than the fine-grained rim. ► The higher hardness of the center was caused by the higher dislocation density.