Rate‐Dependent Mechanical Behavior and Amorphization of Ultrafine‐Grained Boron Carbide

An investigation into mechanical properties and amorphization behavior of ultrafine‐grained (0.3 μm) boron carbide (B₄C) is conducted and compared to a baseline coarse‐grained (10 μm) boron carbide. Static and dynamic uniaxial compressive strength, and static and dynamic Vickers indentation hardness were determined, and Raman spectroscopy was then conducted on indented regions to quantify and compare the intensity of amorphization. In relation to coarse‐grained B₄C the ultrafine‐grained material exhibited, on average, a 33% higher static compressive strength, 20% higher dynamic compressive strength, 10% higher static Vickers hardness, and 23% higher dynamic Vickers hardness. In addition, there was an 18% reduction in indentation‐induced radial crack length in ultrafine‐grained B₄C, which corresponded to an increase in estimated fracture toughness. Although traditional coarse‐grained B₄C exhibits an 8.6% decrease in hardness from the static to dynamic regimes, ultrafine‐grained B₄C showed only negligible change under similar conditions, suggesting a reduced propensity for amorphization. Raman spectroscopic analysis confirmed this result by revealing significantly lower amorphization intensity in ultrafine‐B₄C compared to coarse‐grained B₄C. These results may have significant positive implications in the implementation of ultrafine‐grained boron carbide as a material for improved performance in impact and other high‐pressure applications.