Insights into crystal growth and morphology evolution mechanism of multi-component carbide: Experiments and first-principles calculations

Multi-component transition metal carbides (MTMCs) have garnered significant attention for their outstanding high-temperature stability and versatile properties, which make them ideal candidates for a wide range of industrial applications. However, the underlying mechanisms governing the crystal growth and morphological evolution of MTMCs remain poorly understood, hindering the design of materials with tailored characteristics. In this paper, we employ an in-situ liquid-solid reaction method to synthesize (HfTaZrNbTi)C MTMC powders and explore their crystal growth and morphology evolution. The synthesized (TiZrHfNbTa)C powders exhibit two distinct morphologies: cubic, primarily composed of Ti, Hf, Ta, and Zr with a small amount of Nb, and octahedral, rich in Ti and Ta with minor amounts of Hf, Nb, and Zr. First-principles calculations show that the surface energy of the (100) plane is lower than the (111) plane, leading to the formation of the cubic morphology. The octahedral morphology forms due to decreased mixing entropy and higher theoretical density compared to cubic particles. Our findings provide valuable insights into the crystal growth and morphology evolution mechanisms of high-entropy ceramics, contributing to the rational design of MTMCs with engineered crystal structures for diverse structural and functional applications.