Achieving Dislocation Strengthening in Hafnium Carbide through High Pressure and High Temperature

Abstract

Dislocations profoundly impact the mechanical behavior of materials. High dislocation density induced strengthening is easily achieved in metallic materials, but it is a challenge in ceramics. Here, we highlight the dislocation engineering of an ultrahigh-temperature ceramic, hafnium carbide (HfC), by high-pressure and high-temperature (HPHT) consolidation. The microstructure and temperature-dependent high-pressure consolidation behaviors were systematically investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Our results reveal that pressure-induced intergranular strains promote the generation of high-density dislocations in multiple orientations near grain boundaries and finally enhance the hardness and oxidation resistance of the HfC ceramic. These findings elucidate that dislocation strengthening can be achieved in ultra-high-temperature ceramic HfC, which offers crucial insights for the design and synthesis of advanced ceramic materials.

High hardness (TiZr)C ceramic with dislocation networks

“…10 Nevertheless, inspired by the fact that dislocations could enhance the strength of alloys, 11,12 the prefabrication of dislocations to enhance the hardness of ceramics has attracted much attention. For example, dislocations were generated in HfC ceramics by retaining residual stress during cooling of the sintering process, and then hardness was enhanced 13 ; high density of dislocations was developed in ZrN ceramics irradiated by Au 2+ , 14 leading to irradiation hardening.…”