Ultrafine TiB2-TiNiFeCrCoAl high-entropy alloy composite with enhanced mechanical properties

This paper introduces a novel TiB2−10 wt% TiNiFeCrCoAl high-entropy alloy (HEA) composite with an enhanced hardness and indentation fracture toughness. Comparing with the traditional TiB2-Ni composite, the addition of TiNiFeCrCoAl HEA can remove the oxide impurities in TiB2 to enhance the sintered density; and decrease the solubility of TiB2 in HEA and the solid-liquid surface energy to inhibit the grain growth. The further observation on the microstructure shows the hardening is due to the fine grain size and high contiguity; and the toughening can be attributed to the crack deflection, branching, bridging, and grain pull-out.